# Introduction

Welcome to the documentation repository for Synapse, a Matrix homeserver implementation developed by the matrix.org core team.

## Installing and using Synapse

This documentation covers topics for installation, configuration and maintainence of your Synapse process:

- Learn how to install and configure your own instance, perhaps with Single Sign-On.

- See how to upgrade between Synapse versions.

- Administer your instance using the Admin API, installing pluggable modules, or by accessing the manhole.

- Learn how to read log lines, configure logging or set up structured logging.

- Scale Synapse through additional worker processes.

- Set up monitoring and metrics to keep an eye on your Synapse instance's performance.

## Developing on Synapse

Contributions are welcome! Synapse is primarily written in Python. As a developer, you may be interested in the following documentation:

- Read the Contributing Guide. It is meant to walk new contributors through the process of developing and submitting a change to the Synapse codebase (which is hosted on GitHub).

- Set up your development environment, then learn how to lint and test your code.

- Look at the issue tracker for bugs to fix or features to add. If you're new, it may be best to start with those labeled good first issue.

- Understand how Synapse is built, how to migrate database schemas, learn about federation and how to set up a local federation for development.

- We like to keep our `git` history clean. Learn how to do so!

- And finally, contribute to this documentation! The source for which is located here.

## Donating to Synapse development

Want to help keep Synapse going but don't know how to code? Synapse is a Matrix.org Foundation project. Consider becoming a supportor on Liberapay, Patreon or through PayPal via a one-time donation.

If you are an organisation or enterprise and would like to sponsor development, reach out to us over email at: support (at) matrix.org

## Reporting a security vulnerability

If you've found a security issue in Synapse or any other Matrix.org Foundation project, please report it to us in accordance with our Security Disclosure Policy. Thank you!

# Installation Instructions

## Choosing your server name

It is important to choose the name for your server before you install Synapse, because it cannot be changed later.

The server name determines the "domain" part of user-ids for users on your server: these will all be of the format `@user:my.domain.name`. It also determines how other matrix servers will reach yours for federation.

For a test configuration, set this to the hostname of your server. For a more production-ready setup, you will probably want to specify your domain (`example.com`) rather than a matrix-specific hostname here (in the same way that your email address is probably `user@example.com` rather than `user@email.example.com`) - but doing so may require more advanced setup: see Setting up Federation.

## Installing Synapse

### Prebuilt packages

Prebuilt packages are available for a number of platforms. These are recommended for most users.

#### Docker images and Ansible playbooks

There is an official synapse image available at https://hub.docker.com/r/matrixdotorg/synapse which can be used with the docker-compose file available at contrib/docker. Further information on this including configuration options is available in the README on hub.docker.com.

Alternatively, Andreas Peters (previously Silvio Fricke) has contributed a Dockerfile to automate a synapse server in a single Docker image, at https://hub.docker.com/r/avhost/docker-matrix/tags/

Slavi Pantaleev has created an Ansible playbook, which installs the offical Docker image of Matrix Synapse along with many other Matrix-related services (Postgres database, Element, coturn, ma1sd, SSL support, etc.). For more details, see https://github.com/spantaleev/matrix-docker-ansible-deploy

#### Debian/Ubuntu

##### Matrix.org packages

Matrix.org provides Debian/Ubuntu packages of Synapse, for the amd64 architecture via https://packages.matrix.org/debian/.

To install the latest release:

    sudo apt install -y lsb-release wget apt-transport-https
    sudo wget -O /usr/share/keyrings/matrix-org-archive-keyring.gpg https://packages.matrix.org/debian/matrix-org-archive-keyring.gpg
    echo "deb [signed-by=/usr/share/keyrings/matrix-org-archive-keyring.gpg] https://packages.matrix.org/debian/ $(lsb_release -cs) main" |
        sudo tee /etc/apt/sources.list.d/matrix-org.list
    sudo apt update
    sudo apt install matrix-synapse-py3

Packages are also published for release candidates. To enable the prerelease channel, add `prerelease` to the `sources.list` line. For example:

    sudo wget -O /usr/share/keyrings/matrix-org-archive-keyring.gpg https://packages.matrix.org/debian/matrix-org-archive-keyring.gpg
    echo "deb [signed-by=/usr/share/keyrings/matrix-org-archive-keyring.gpg] https://packages.matrix.org/debian/ $(lsb_release -cs) main prerelease" |
        sudo tee /etc/apt/sources.list.d/matrix-org.list
    sudo apt update
    sudo apt install matrix-synapse-py3

The fingerprint of the repository signing key (as shown by `gpg /usr/share/keyrings/matrix-org-archive-keyring.gpg`) is `AAF9AE843A7584B5A3E4CD2BCF45A512DE2DA058`.

##### Downstream Debian packages

We do not recommend using the packages from the default Debian `buster` repository at this time, as they are old and suffer from known security vulnerabilities. You can install the latest version of Synapse from our repository or from `buster-backports`. Please see the Debian documentation for information on how to use backports.

If you are using Debian `sid` or testing, Synapse is available in the default repositories and it should be possible to install it simply with:

    sudo apt install matrix-synapse

##### Downstream Ubuntu packages

We do not recommend using the packages in the default Ubuntu repository at this time, as they are old and suffer from known security vulnerabilities. The latest version of Synapse can be installed from our repository.

#### Fedora

Synapse is in the Fedora repositories as `matrix-synapse`:

    sudo dnf install matrix-synapse

Oleg Girko provides Fedora RPMs at https://obs.infoserver.lv/project/monitor/matrix-synapse

#### OpenSUSE

Synapse is in the OpenSUSE repositories as `matrix-synapse`:

    sudo zypper install matrix-synapse

#### SUSE Linux Enterprise Server

Unofficial package are built for SLES 15 in the openSUSE:Backports:SLE-15 repository at https://download.opensuse.org/repositories/openSUSE:/Backports:/SLE-15/standard/

#### ArchLinux

The quickest way to get up and running with ArchLinux is probably with the community package https://www.archlinux.org/packages/community/any/matrix-synapse/, which should pull in most of the necessary dependencies.

pip may be outdated (6.0.7-1 and needs to be upgraded to 6.0.8-1 ):

    sudo pip install --upgrade pip

If you encounter an error with lib bcrypt causing an Wrong ELF Class: ELFCLASS32 (x64 Systems), you may need to reinstall py-bcrypt to correctly compile it under the right architecture. (This should not be needed if installing under virtualenv):

    sudo pip uninstall py-bcrypt
    sudo pip install py-bcrypt

#### Void Linux

Synapse can be found in the void repositories as 'synapse':

    xbps-install -Su
    xbps-install -S synapse

#### FreeBSD

Synapse can be installed via FreeBSD Ports or Packages contributed by Brendan Molloy from:

- Ports: `cd /usr/ports/net-im/py-matrix-synapse && make install clean`
- Packages: `pkg install py37-matrix-synapse`

#### OpenBSD

As of OpenBSD 6.7 Synapse is available as a pre-compiled binary. The filesystem underlying the homeserver directory (defaults to `/var/synapse`) has to be mounted with `wxallowed` (cf. `mount(8)`), so creating a separate filesystem and mounting it to `/var/synapse` should be taken into consideration.

Installing Synapse:

    doas pkg_add synapse

#### NixOS

Robin Lambertz has packaged Synapse for NixOS at: https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/misc/matrix-synapse.nix

### Installing as a Python module from PyPI

It's also possible to install Synapse as a Python module from PyPI.

When following this route please make sure that the Platform-specific prerequisites are already installed.

System requirements:

- POSIX-compliant system (tested on Linux & OS X)
- Python 3.6 or later, up to Python 3.9.
- At least 1GB of free RAM if you want to join large public rooms like #matrix:matrix.org

To install the Synapse homeserver run:

    mkdir -p ~/synapse
    virtualenv -p python3 ~/synapse/env
    source ~/synapse/env/bin/activate
    pip install --upgrade pip
    pip install --upgrade setuptools
    pip install matrix-synapse

This will download Synapse from PyPI and install it, along with the python libraries it uses, into a virtual environment under `~/synapse/env`. Feel free to pick a different directory if you prefer.

This Synapse installation can then be later upgraded by using pip again with the update flag:

    source ~/synapse/env/bin/activate
    pip install -U matrix-synapse

Before you can start Synapse, you will need to generate a configuration file. To do this, run (in your virtualenv, as before):

    cd ~/synapse
    python -m synapse.app.homeserver \
        --server-name my.domain.name \
        --config-path homeserver.yaml \
        --generate-config \
        --report-stats=[yes|no]

... substituting an appropriate value for `--server-name`.

This command will generate you a config file that you can then customise, but it will also generate a set of keys for you. These keys will allow your homeserver to identify itself to other homeserver, so don't lose or delete them. It would be wise to back them up somewhere safe. (If, for whatever reason, you do need to change your homeserver's keys, you may find that other homeserver have the old key cached. If you update the signing key, you should change the name of the key in the `<server name>.signing.key` file (the second word) to something different. See the spec for more information on key management).

To actually run your new homeserver, pick a working directory for Synapse to run (e.g. `~/synapse`), and:

    cd ~/synapse
    source env/bin/activate
    synctl start

#### Platform-specific prerequisites

Synapse is written in Python but some of the libraries it uses are written in C. So before we can install Synapse itself we need a working C compiler and the header files for Python C extensions.

##### Debian/Ubuntu/Raspbian

Installing prerequisites on Ubuntu or Debian:

    sudo apt install build-essential python3-dev libffi-dev \
                         python3-pip python3-setuptools sqlite3 \
                         libssl-dev virtualenv libjpeg-dev libxslt1-dev

##### ArchLinux

Installing prerequisites on ArchLinux:

    sudo pacman -S base-devel python python-pip \
                   python-setuptools python-virtualenv sqlite3

##### CentOS/Fedora

Installing prerequisites on CentOS or Fedora Linux:

    sudo dnf install libtiff-devel libjpeg-devel libzip-devel freetype-devel \
                     libwebp-devel libxml2-devel libxslt-devel libpq-devel \
                     python3-virtualenv libffi-devel openssl-devel python3-devel
    sudo dnf groupinstall "Development Tools"

##### macOS

Installing prerequisites on macOS:

You may need to install the latest Xcode developer tools:

    xcode-select --install

On ARM-based Macs you may need to explicitly install libjpeg which is a pillow dependency. You can use Homebrew (https://brew.sh):

     brew install jpeg

On macOS Catalina (10.15) you may need to explicitly install OpenSSL via brew and inform `pip` about it so that `psycopg2` builds:

    brew install openssl@1.1
    export LDFLAGS="-L/usr/local/opt/openssl/lib"
    export CPPFLAGS="-I/usr/local/opt/openssl/include"

##### OpenSUSE

Installing prerequisites on openSUSE:

    sudo zypper in -t pattern devel_basis
    sudo zypper in python-pip python-setuptools sqlite3 python-virtualenv \
                   python-devel libffi-devel libopenssl-devel libjpeg62-devel

##### OpenBSD

A port of Synapse is available under `net/synapse`. The filesystem underlying the homeserver directory (defaults to `/var/synapse`) has to be mounted with `wxallowed` (cf. `mount(8)`), so creating a separate filesystem and mounting it to `/var/synapse` should be taken into consideration.

To be able to build Synapse's dependency on python the `WRKOBJDIR` (cf. `bsd.port.mk(5)`) for building python, too, needs to be on a filesystem mounted with `wxallowed` (cf. `mount(8)`).

Creating a `WRKOBJDIR` for building python under `/usr/local` (which on a default OpenBSD installation is mounted with `wxallowed`):

    doas mkdir /usr/local/pobj_wxallowed

Assuming `PORTS_PRIVSEP=Yes` (cf. `bsd.port.mk(5)`) and `SUDO=doas` are configured in `/etc/mk.conf`:

    doas chown _pbuild:_pbuild /usr/local/pobj_wxallowed

Setting the `WRKOBJDIR` for building python:

    echo WRKOBJDIR_lang/python/3.7=/usr/local/pobj_wxallowed  \\nWRKOBJDIR_lang/python/2.7=/usr/local/pobj_wxallowed >> /etc/mk.conf

Building Synapse:

    cd /usr/ports/net/synapse
    make install

##### Windows

If you wish to run or develop Synapse on Windows, the Windows Subsystem For Linux provides a Linux environment on Windows 10 which is capable of using the Debian, Fedora, or source installation methods. More information about WSL can be found at https://docs.microsoft.com/en-us/windows/wsl/install-win10 for Windows 10 and https://docs.microsoft.com/en-us/windows/wsl/install-on-server for Windows Server.

## Setting up Synapse

Once you have installed synapse as above, you will need to configure it.

### Using PostgreSQL

By default Synapse uses an SQLite database and in doing so trades performance for convenience. Almost all installations should opt to use PostgreSQL instead. Advantages include:

- significant performance improvements due to the superior threading and caching model, smarter query optimiser
- allowing the DB to be run on separate hardware

For information on how to install and use PostgreSQL in Synapse, please see Using Postgres

SQLite is only acceptable for testing purposes. SQLite should not be used in a production server. Synapse will perform poorly when using SQLite, especially when participating in large rooms.

### TLS certificates

The default configuration exposes a single HTTP port on the local interface: `http://localhost:8008`. It is suitable for local testing, but for any practical use, you will need Synapse's APIs to be served over HTTPS.

The recommended way to do so is to set up a reverse proxy on port `8448`. You can find documentation on doing so in the reverse proxy documentation.

Alternatively, you can configure Synapse to expose an HTTPS port. To do so, you will need to edit `homeserver.yaml`, as follows:

- First, under the `listeners` section, uncomment the configuration for the TLS-enabled listener. (Remove the hash sign (`#`) at the start of each line). The relevant lines are like this:

      - port: 8448
        type: http
        tls: true
        resources:
          - names: [client, federation]

- You will also need to uncomment the `tls_certificate_path` and `tls_private_key_path` lines under the `TLS` section. You will need to manage provisioning of these certificates yourself.

  If you are using your own certificate, be sure to use a `.pem` file that includes the full certificate chain including any intermediate certificates (for instance, if using certbot, use `fullchain.pem` as your certificate, not `cert.pem`).

For a more detailed guide to configuring your server for federation, see Federation.

### Client Well-Known URI

Setting up the client Well-Known URI is optional but if you set it up, it will allow users to enter their full username (e.g. `@user:<server_name>`) into clients which support well-known lookup to automatically configure the homeserver and identity server URLs. This is useful so that users don't have to memorize or think about the actual homeserver URL you are using.

The URL `https://<server_name>/.well-known/matrix/client` should return JSON in the following format.

    {
      "m.homeserver": {
        "base_url": "https://<matrix.example.com>"
      }
    }

It can optionally contain identity server information as well.

    {
      "m.homeserver": {
        "base_url": "https://<matrix.example.com>"
      },
      "m.identity_server": {
        "base_url": "https://<identity.example.com>"
      }
    }

To work in browser based clients, the file must be served with the appropriate Cross-Origin Resource Sharing (CORS) headers. A recommended value would be `Access-Control-Allow-Origin: *` which would allow all browser based clients to view it.

In nginx this would be something like:

    location /.well-known/matrix/client {
        return 200 '{"m.homeserver": {"base_url": "https://<matrix.example.com>"}}';
        default_type application/json;
        add_header Access-Control-Allow-Origin *;
    }

You should also ensure the `public_baseurl` option in `homeserver.yaml` is set correctly. `public_baseurl` should be set to the URL that clients will use to connect to your server. This is the same URL you put for the `m.homeserver` `base_url` above.

    public_baseurl: "https://<matrix.example.com>"

### Email

It is desirable for Synapse to have the capability to send email. This allows Synapse to send password reset emails, send verifications when an email address is added to a user's account, and send email notifications to users when they receive new messages.

To configure an SMTP server for Synapse, modify the configuration section headed `email`, and be sure to have at least the `smtp_host`, `smtp_port` and `notif_from` fields filled out. You may also need to set `smtp_user`, `smtp_pass`, and `require_transport_security`.

If email is not configured, password reset, registration and notifications via email will be disabled.

### Registering a user

The easiest way to create a new user is to do so from a client like Element.

Alternatively, you can do so from the command line. This can be done as follows:

1. If synapse was installed via pip, activate the virtualenv as follows (if Synapse was installed via a prebuilt package, `register_new_matrix_user` should already be on the search path):

       cd ~/synapse
       source env/bin/activate
       synctl start # if not already running

2. Run the following command:

       register_new_matrix_user -c homeserver.yaml http://localhost:8008

This will prompt you to add details for the new user, and will then connect to the running Synapse to create the new user. For example:

    New user localpart: erikj
    Password:
    Confirm password:
    Make admin [no]:
    Success!

This process uses a setting `registration_shared_secret` in `homeserver.yaml`, which is shared between Synapse itself and the `register_new_matrix_user` script. It doesn't matter what it is (a random value is generated by `--generate-config`), but it should be kept secret, as anyone with knowledge of it can register users, including admin accounts, on your server even if `enable_registration` is `false`.

### Setting up a TURN server

For reliable VoIP calls to be routed via this homeserver, you MUST configure a TURN server. See TURN setup for details.

### URL previews

Synapse includes support for previewing URLs, which is disabled by default. To turn it on you must enable the `url_preview_enabled: True` config parameter and explicitly specify the IP ranges that Synapse is not allowed to spider for previewing in the `url_preview_ip_range_blacklist` configuration parameter. This is critical from a security perspective to stop arbitrary Matrix users spidering 'internal' URLs on your network. At the very least we recommend that your loopback and RFC1918 IP addresses are blacklisted.

This also requires the optional `lxml` python dependency to be installed. This in turn requires the `libxml2` library to be available - on Debian/Ubuntu this means `apt-get install libxml2-dev`, or equivalent for your OS.

### Troubleshooting Installation

`pip` seems to leak lots of memory during installation. For instance, a Linux host with 512MB of RAM may run out of memory whilst installing Twisted. If this happens, you will have to individually install the dependencies which are failing, e.g.:

    pip install twisted

If you have any other problems, feel free to ask in #synapse:matrix.org.

# Using Postgres

Synapse supports PostgreSQL versions 9.6 or later.

## Install postgres client libraries

Synapse will require the python postgres client library in order to connect to a postgres database.

- If you are using the matrix.org debian/ubuntu packages, the necessary python library will already be installed, but you will need to ensure the low-level postgres library is installed, which you can do with `apt install libpq5`.

- For other pre-built packages, please consult the documentation from the relevant package.

- If you installed synapse in a virtualenv, you can install the library with:

      ~/synapse/env/bin/pip install "matrix-synapse[postgres]"

  (substituting the path to your virtualenv for `~/synapse/env`, if you used a different path). You will require the postgres development files. These are in the `libpq-dev` package on Debian-derived distributions.

## Set up database

Assuming your PostgreSQL database user is called `postgres`, first authenticate as the database user with:

    su - postgres
    # Or, if your system uses sudo to get administrative rights
    sudo -u postgres bash

Then, create a postgres user and a database with:

    # this will prompt for a password for the new user
    createuser --pwprompt synapse_user

    createdb --encoding=UTF8 --locale=C --template=template0 --owner=synapse_user synapse

The above will create a user called `synapse_user`, and a database called `synapse`.

Note that the PostgreSQL database must have the correct encoding set (as shown above), otherwise it will not be able to store UTF8 strings.

You may need to enable password authentication so `synapse_user` can connect to the database. See https://www.postgresql.org/docs/current/auth-pg-hba-conf.html.

## Synapse config

When you are ready to start using PostgreSQL, edit the `database` section in your config file to match the following lines:

    database:
      name: psycopg2
      args:
        user: <user>
        password: <pass>
        database: <db>
        host: <host>
        cp_min: 5
        cp_max: 10

All key, values in `args` are passed to the `psycopg2.connect(..)` function, except keys beginning with `cp_`, which are consumed by the twisted adbapi connection pool. See the libpq documentation for a list of options which can be passed.

You should consider tuning the `args.keepalives_*` options if there is any danger of the connection between your homeserver and database dropping, otherwise Synapse may block for an extended period while it waits for a response from the database server. Example values might be:

    database:
      args:
        # ... as above

        # seconds of inactivity after which TCP should send a keepalive message to the server
        keepalives_idle: 10

        # the number of seconds after which a TCP keepalive message that is not
        # acknowledged by the server should be retransmitted
        keepalives_interval: 10

        # the number of TCP keepalives that can be lost before the client's connection
        # to the server is considered dead
        keepalives_count: 3

## Tuning Postgres

The default settings should be fine for most deployments. For larger scale deployments tuning some of the settings is recommended, details of which can be found at https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server.

In particular, we've found tuning the following values helpful for performance:

- `shared_buffers`
- `effective_cache_size`
- `work_mem`
- `maintenance_work_mem`
- `autovacuum_work_mem`

Note that the appropriate values for those fields depend on the amount of free memory the database host has available.

## Porting from SQLite

### Overview

The script `synapse_port_db` allows porting an existing synapse server backed by SQLite to using PostgreSQL. This is done in as a two phase process:

1. Copy the existing SQLite database to a separate location and run the port script against that offline database.
2. Shut down the server. Rerun the port script to port any data that has come in since taking the first snapshot. Restart server against the PostgreSQL database.

The port script is designed to be run repeatedly against newer snapshots of the SQLite database file. This makes it safe to repeat step 1 if there was a delay between taking the previous snapshot and being ready to do step 2.

It is safe to at any time kill the port script and restart it.

Note that the database may take up significantly more (25% - 100% more) space on disk after porting to Postgres.

### Using the port script

Firstly, shut down the currently running synapse server and copy its database file (typically `homeserver.db`) to another location. Once the copy is complete, restart synapse. For instance:

    ./synctl stop
    cp homeserver.db homeserver.db.snapshot
    ./synctl start

Copy the old config file into a new config file:

    cp homeserver.yaml homeserver-postgres.yaml

Edit the database section as described in the section Synapse config above and with the SQLite snapshot located at `homeserver.db.snapshot` simply run:

    synapse_port_db --sqlite-database homeserver.db.snapshot \
        --postgres-config homeserver-postgres.yaml

The flag `--curses` displays a coloured curses progress UI.

If the script took a long time to complete, or time has otherwise passed since the original snapshot was taken, repeat the previous steps with a newer snapshot.

To complete the conversion shut down the synapse server and run the port script one last time, e.g. if the SQLite database is at `homeserver.db` run:

    synapse_port_db --sqlite-database homeserver.db \
        --postgres-config homeserver-postgres.yaml

Once that has completed, change the synapse config to point at the PostgreSQL database configuration file `homeserver-postgres.yaml`:

    ./synctl stop
    mv homeserver.yaml homeserver-old-sqlite.yaml
    mv homeserver-postgres.yaml homeserver.yaml
    ./synctl start

Synapse should now be running against PostgreSQL.

## Troubleshooting

### Alternative auth methods

If you get an error along the lines of `FATAL: Ident authentication failed for user "synapse_user"`, you may need to use an authentication method other than `ident`:

- If the `synapse_user` user has a password, add the password to the `database:` section of `homeserver.yaml`. Then add the following to `pg_hba.conf`:

      host    synapse     synapse_user    ::1/128     md5  # or `scram-sha-256` instead of `md5` if you use that

- If the `synapse_user` user does not have a password, then a password doesn't have to be added to `homeserver.yaml`. But the following does need to be added to `pg_hba.conf`:

      host    synapse     synapse_user    ::1/128     trust

Note that line order matters in `pg_hba.conf`, so make sure that if you do add a new line, it is inserted before:

    host    all         all             ::1/128     ident

### Fixing incorrect `COLLATE` or `CTYPE`

Synapse will refuse to set up a new database if it has the wrong values of `COLLATE` and `CTYPE` set, and will log warnings on existing databases. Using different locales can cause issues if the locale library is updated from underneath the database, or if a different version of the locale is used on any replicas.

The safest way to fix the issue is to dump the database and recreate it with the correct locale parameter (as shown above). It is also possible to change the parameters on a live database and run a `REINDEX` on the entire database, however extreme care must be taken to avoid database corruption.

Note that the above may fail with an error about duplicate rows if corruption has already occurred, and such duplicate rows will need to be manually removed.

### Fixing inconsistent sequences error

Synapse uses Postgres sequences to generate IDs for various tables. A sequence and associated table can get out of sync if, for example, Synapse has been downgraded and then upgraded again.

To fix the issue shut down Synapse (including any and all workers) and run the SQL command included in the error message. Once done Synapse should start successfully.

# Using a reverse proxy with Synapse

It is recommended to put a reverse proxy such as nginx, Apache, Caddy, HAProxy or relayd in front of Synapse. One advantage of doing so is that it means that you can expose the default https port (443) to Matrix clients without needing to run Synapse with root privileges.

You should configure your reverse proxy to forward requests to `/_matrix` or `/_synapse/client` to Synapse, and have it set the `X-Forwarded-For` and `X-Forwarded-Proto` request headers.

You should remember that Matrix clients and other Matrix servers do not necessarily need to connect to your server via the same server name or port. Indeed, clients will use port 443 by default, whereas servers default to port 8448. Where these are different, we refer to the 'client port' and the 'federation port'. See the Matrix specification for more details of the algorithm used for federation connections, and Delegation for instructions on setting up delegation.

NOTE: Your reverse proxy must not `canonicalise` or `normalise` the requested URI in any way (for example, by decoding `%xx` escapes). Beware that Apache will canonicalise URIs unless you specify `nocanon`.

Let's assume that we expect clients to connect to our server at `https://matrix.example.com`, and other servers to connect at `https://example.com:8448`. The following sections detail the configuration of the reverse proxy and the homeserver.

## Homeserver Configuration

The HTTP configuration will need to be updated for Synapse to correctly record client IP addresses and generate redirect URLs while behind a reverse proxy.

In `homeserver.yaml` set `x_forwarded: true` in the port 8008 section and consider setting `bind_addresses: ['127.0.0.1']` so that the server only listens to traffic on localhost. (Do not change `bind_addresses` to `127.0.0.1` when using a containerized Synapse, as that will prevent it from responding to proxied traffic.)

## Reverse-proxy configuration examples

NOTE: You only need one of these.

### nginx

    server {
        listen 443 ssl http2;
        listen [::]:443 ssl http2;

        # For the federation port
        listen 8448 ssl http2 default_server;
        listen [::]:8448 ssl http2 default_server;

        server_name matrix.example.com;

        location ~* ^(\/_matrix|\/_synapse\/client) {
            # note: do not add a path (even a single /) after the port in `proxy_pass`,
            # otherwise nginx will canonicalise the URI and cause signature verification
            # errors.
            proxy_pass http://localhost:8008;
            proxy_set_header X-Forwarded-For $remote_addr;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header Host $host;

            # Nginx by default only allows file uploads up to 1M in size
            # Increase client_max_body_size to match max_upload_size defined in homeserver.yaml
            client_max_body_size 50M;
        }
    }

### Caddy v1

    matrix.example.com {
      proxy /_matrix http://localhost:8008 {
        transparent
      }

      proxy /_synapse/client http://localhost:8008 {
        transparent
      }
    }

    example.com:8448 {
      proxy / http://localhost:8008 {
        transparent
      }
    }

### Caddy v2

    matrix.example.com {
      reverse_proxy /_matrix/* http://localhost:8008
      reverse_proxy /_synapse/client/* http://localhost:8008
    }

    example.com:8448 {
      reverse_proxy http://localhost:8008
    }

Delegation example:

    (matrix-well-known-header) {
        # Headers
        header Access-Control-Allow-Origin "*"
        header Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS"
        header Access-Control-Allow-Headers "Origin, X-Requested-With, Content-Type, Accept, Authorization"
        header Content-Type "application/json"
    }

    example.com {
        handle /.well-known/matrix/server {
            import matrix-well-known-header
            respond `{"m.server":"matrix.example.com:443"}`
        }

        handle /.well-known/matrix/client {
            import matrix-well-known-header
            respond `{"m.homeserver":{"base_url":"https://matrix.example.com"},"m.identity_server":{"base_url":"https://identity.example.com"}}`
        }
    }

    matrix.example.com {
        reverse_proxy /_matrix/* http://localhost:8008
        reverse_proxy /_synapse/client/* http://localhost:8008
    }

### Apache

    <VirtualHost *:443>
        SSLEngine on
        ServerName matrix.example.com

        RequestHeader set "X-Forwarded-Proto" expr=%{REQUEST_SCHEME}
        AllowEncodedSlashes NoDecode
        ProxyPreserveHost on
        ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
        ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
        ProxyPass /_synapse/client http://127.0.0.1:8008/_synapse/client nocanon
        ProxyPassReverse /_synapse/client http://127.0.0.1:8008/_synapse/client
    </VirtualHost>

    <VirtualHost *:8448>
        SSLEngine on
        ServerName example.com

        RequestHeader set "X-Forwarded-Proto" expr=%{REQUEST_SCHEME}
        AllowEncodedSlashes NoDecode
        ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
        ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
    </VirtualHost>

NOTE: ensure the `nocanon` options are included.

NOTE 2: It appears that Synapse is currently incompatible with the ModSecurity module for Apache (`mod_security2`). If you need it enabled for other services on your web server, you can disable it for Synapse's two VirtualHosts by including the following lines before each of the two `</VirtualHost>` above:

    <IfModule security2_module>
        SecRuleEngine off
    </IfModule>

NOTE 3: Missing `ProxyPreserveHost on` can lead to a redirect loop.

### HAProxy

    frontend https
      bind :::443 v4v6 ssl crt /etc/ssl/haproxy/ strict-sni alpn h2,http/1.1
      http-request set-header X-Forwarded-Proto https if { ssl_fc }
      http-request set-header X-Forwarded-Proto http if !{ ssl_fc }
      http-request set-header X-Forwarded-For %[src]

      # Matrix client traffic
      acl matrix-host hdr(host) -i matrix.example.com
      acl matrix-path path_beg /_matrix
      acl matrix-path path_beg /_synapse/client

      use_backend matrix if matrix-host matrix-path

    frontend matrix-federation
      bind :::8448 v4v6 ssl crt /etc/ssl/haproxy/synapse.pem alpn h2,http/1.1
      http-request set-header X-Forwarded-Proto https if { ssl_fc }
      http-request set-header X-Forwarded-Proto http if !{ ssl_fc }
      http-request set-header X-Forwarded-For %[src]

      default_backend matrix

    backend matrix
      server matrix 127.0.0.1:8008

### Relayd

    table <webserver>    { 127.0.0.1 }
    table <matrixserver> { 127.0.0.1 }

    http protocol "https" {
        tls { no tlsv1.0, ciphers "HIGH" }
        tls keypair "example.com"
        match header set "X-Forwarded-For"   value "$REMOTE_ADDR"
        match header set "X-Forwarded-Proto" value "https"

        # set CORS header for .well-known/matrix/server, .well-known/matrix/client
        # httpd does not support setting headers, so do it here
        match request path "/.well-known/matrix/*" tag "matrix-cors"
        match response tagged "matrix-cors" header set "Access-Control-Allow-Origin" value "*"

        pass quick path "/_matrix/*"         forward to <matrixserver>
        pass quick path "/_synapse/client/*" forward to <matrixserver>

        # pass on non-matrix traffic to webserver
        pass                                 forward to <webserver>
    }

    relay "https_traffic" {
        listen on egress port 443 tls
        protocol "https"
        forward to <matrixserver> port 8008 check tcp
        forward to <webserver>    port 8080 check tcp
    }

    http protocol "matrix" {
        tls { no tlsv1.0, ciphers "HIGH" }
        tls keypair "example.com"
        block
        pass quick path "/_matrix/*"         forward to <matrixserver>
        pass quick path "/_synapse/client/*" forward to <matrixserver>
    }

    relay "matrix_federation" {
        listen on egress port 8448 tls
        protocol "matrix"
        forward to <matrixserver> port 8008 check tcp
    }

## Health check endpoint

Synapse exposes a health check endpoint for use by reverse proxies. Each configured HTTP listener has a `/health` endpoint which always returns 200 OK (and doesn't get logged).

## Synapse administration endpoints

Endpoints for administering your Synapse instance are placed under `/_synapse/admin`. These require authentication through an access token of an admin user. However as access to these endpoints grants the caller a lot of power, we do not recommend exposing them to the public internet without good reason.

# Using a forward proxy with Synapse

You can use Synapse with a forward or outbound proxy. An example of when this is necessary is in corporate environments behind a DMZ (demilitarized zone). Synapse supports routing outbound HTTP(S) requests via a proxy. Only HTTP(S) proxy is supported, not SOCKS proxy or anything else.

## Configure

The `http_proxy`, `https_proxy`, `no_proxy` environment variables are used to specify proxy settings. The environment variable is not case sensitive.

- `http_proxy`: Proxy server to use for HTTP requests.
- `https_proxy`: Proxy server to use for HTTPS requests.
- `no_proxy`: Comma-separated list of hosts, IP addresses, or IP ranges in CIDR format which should not use the proxy. Synapse will directly connect to these hosts.

The `http_proxy` and `https_proxy` environment variables have the form: `[scheme://][<username>:<password>@]<host>[:<port>]`

- Supported schemes are `http://` and `https://`. The default scheme is `http://` for compatibility reasons; it is recommended to set a scheme. If scheme is set to `https://` the connection uses TLS between Synapse and the proxy.

  NOTE: Synapse validates the certificates. If the certificate is not valid, then the connection is dropped.

- Default port if not given is `1080`.

- Username and password are optional and will be used to authenticate against the proxy.

Examples

- HTTP_PROXY=http://USERNAME:PASSWORD@10.0.1.1:8080/
- HTTPS_PROXY=http://USERNAME:PASSWORD@proxy.example.com:8080/
- NO_PROXY=master.hostname.example.com,10.1.0.0/16,172.30.0.0/16

NOTE: Synapse does not apply the IP blacklist to connections through the proxy (since the DNS resolution is done by the proxy). It is expected that the proxy or firewall will apply blacklisting of IP addresses.

## Connection types

The proxy will be used for:

- push
- url previews
- phone-home stats
- recaptcha validation
- CAS auth validation
- OpenID Connect
- Outbound federation
- Federation (checking public key revocation)
- Fetching public keys of other servers
- Downloading remote media

It will not be used for:

- Application Services
- Identity servers
- In worker configurations
  - connections between workers
  - connections from workers to Redis

## Troubleshooting

If a proxy server is used with TLS (HTTPS) and no connections are established, it is most likely due to the proxy's certificates. To test this, the validation in Synapse can be deactivated.

NOTE: This has an impact on security and is for testing purposes only!

To deactivate the certificate validation, the following setting must be made in homserver.yaml.

    use_insecure_ssl_client_just_for_testing_do_not_use: true

# Overview

This document explains how to enable VoIP relaying on your Home Server with TURN.

The synapse Matrix Home Server supports integration with TURN server via the TURN server REST API. This allows the Home Server to generate credentials that are valid for use on the TURN server through the use of a secret shared between the Home Server and the TURN server.

The following sections describe how to install coturn (which implements the TURN REST API) and integrate it with synapse.

## Requirements

For TURN relaying with `coturn` to work, it must be hosted on a server/endpoint with a public IP.

Hosting TURN behind a NAT (even with appropriate port forwarding) is known to cause issues and to often not work.

## `coturn` setup

### Initial installation

The TURN daemon `coturn` is available from a variety of sources such as native package managers, or installation from source.

#### Debian installation

Just install the debian package:

    apt install coturn

This will install and start a systemd service called `coturn`.

#### Source installation

1. Download the latest release from github. Unpack it and `cd` into the directory.

2. Configure it:

       ./configure

   You may need to install `libevent2`: if so, you should do so in the way recommended by your operating system. You can ignore warnings about lack of database support: a database is unnecessary for this purpose.

3. Build and install it:

       make
       make install

### Configuration

1. Create or edit the config file in `/etc/turnserver.conf`. The relevant lines, with example values, are:

       use-auth-secret
       static-auth-secret=[your secret key here]
       realm=turn.myserver.org

   See `turnserver.conf` for explanations of the options. One way to generate the `static-auth-secret` is with `pwgen`:

       pwgen -s 64 1

   A `realm` must be specified, but its value is somewhat arbitrary. (It is sent to clients as part of the authentication flow.) It is conventional to set it to be your server name.

2. You will most likely want to configure coturn to write logs somewhere. The easiest way is normally to send them to the syslog:

       syslog

   (in which case, the logs will be available via `journalctl -u coturn` on a systemd system). Alternatively, coturn can be configured to write to a logfile - check the example config file supplied with coturn.

3. Consider your security settings. TURN lets users request a relay which will connect to arbitrary IP addresses and ports. The following configuration is suggested as a minimum starting point:

       # VoIP traffic is all UDP. There is no reason to let users connect to arbitrary TCP endpoints via the relay.
       no-tcp-relay

       # don't let the relay ever try to connect to private IP address ranges within your network (if any)
       # given the turn server is likely behind your firewall, remember to include any privileged public IPs too.
       denied-peer-ip=10.0.0.0-10.255.255.255
       denied-peer-ip=192.168.0.0-192.168.255.255
       denied-peer-ip=172.16.0.0-172.31.255.255

       # special case the turn server itself so that client->TURN->TURN->client flows work
       allowed-peer-ip=10.0.0.1

       # consider whether you want to limit the quota of relayed streams per user (or total) to avoid risk of DoS.
       user-quota=12 # 4 streams per video call, so 12 streams = 3 simultaneous relayed calls per user.
       total-quota=1200

4. Also consider supporting TLS/DTLS. To do this, add the following settings to `turnserver.conf`:

       # TLS certificates, including intermediate certs.
       # For Let's Encrypt certificates, use `fullchain.pem` here.
       cert=/path/to/fullchain.pem

       # TLS private key file
       pkey=/path/to/privkey.pem

   In this case, replace the `turn:` schemes in the `turn_uri` settings below with `turns:`.

   We recommend that you only try to set up TLS/DTLS once you have set up a basic installation and got it working.

5. Ensure your firewall allows traffic into the TURN server on the ports you've configured it to listen on (By default: 3478 and 5349 for TURN traffic (remember to allow both TCP and UDP traffic), and ports 49152-65535 for the UDP relay.)

6. We do not recommend running a TURN server behind NAT, and are not aware of anyone doing so successfully.

   If you want to try it anyway, you will at least need to tell coturn its external IP address:

       external-ip=192.88.99.1

   ... and your NAT gateway must forward all of the relayed ports directly (eg, port 56789 on the external IP must be always be forwarded to port 56789 on the internal IP).

   If you get this working, let us know!

7. (Re)start the turn server:

   - If you used the Debian package (or have set up a systemd unit yourself):

         systemctl restart coturn

   - If you installed from source:

         bin/turnserver -o

## Synapse setup

Your home server configuration file needs the following extra keys:

1. "`turn_uris`": This needs to be a yaml list of public-facing URIs for your TURN server to be given out to your clients. Add separate entries for each transport your TURN server supports.
2. "`turn_shared_secret`": This is the secret shared between your Home server and your TURN server, so you should set it to the same string you used in turnserver.conf.
3. "`turn_user_lifetime`": This is the amount of time credentials generated by your Home Server are valid for (in milliseconds). Shorter times offer less potential for abuse at the expense of increased traffic between web clients and your home server to refresh credentials. The TURN REST API specification recommends one day (86400000).
4. "`turn_allow_guests`": Whether to allow guest users to use the TURN server. This is enabled by default, as otherwise VoIP will not work reliably for guests. However, it does introduce a security risk as it lets guests connect to arbitrary endpoints without having gone through a CAPTCHA or similar to register a real account.

As an example, here is the relevant section of the config file for `matrix.org`. The `turn_uris` are appropriate for TURN servers listening on the default ports, with no TLS.

    turn_uris: [ "turn:turn.matrix.org?transport=udp", "turn:turn.matrix.org?transport=tcp" ]
    turn_shared_secret: "n0t4ctuAllymatr1Xd0TorgSshar3d5ecret4obvIousreAsons"
    turn_user_lifetime: 86400000
    turn_allow_guests: True

After updating the homeserver configuration, you must restart synapse:

- If you use synctl:

      cd /where/you/run/synapse
      ./synctl restart

- If you use systemd:

      systemctl restart matrix-synapse.service

... and then reload any clients (or wait an hour for them to refresh their settings).

## Troubleshooting

The normal symptoms of a misconfigured TURN server are that calls between devices on different networks ring, but get stuck at "call connecting". Unfortunately, troubleshooting this can be tricky.

Here are a few things to try:

- Check that your TURN server is not behind NAT. As above, we're not aware of anyone who has successfully set this up.

- Check that you have opened your firewall to allow TCP and UDP traffic to the TURN ports (normally 3478 and 5479).

- Check that you have opened your firewall to allow UDP traffic to the UDP relay ports (49152-65535 by default).

- Some WebRTC implementations (notably, that of Google Chrome) appear to get confused by TURN servers which are reachable over IPv6 (this appears to be an unexpected side-effect of its handling of multiple IP addresses as defined by `draft-ietf-rtcweb-ip-handling`).

  Try removing any AAAA records for your TURN server, so that it is only reachable over IPv4.

- Enable more verbose logging in coturn via the `verbose` setting:

      verbose

  ... and then see if there are any clues in its logs.

- If you are using a browser-based client under Chrome, check `chrome://webrtc-internals/` for insights into the internals of the negotiation. On Firefox, check the "Connection Log" on `about:webrtc`.

  (Understanding the output is beyond the scope of this document!)

- You can test your Matrix homeserver TURN setup with https://test.voip.librepush.net/. Note that this test is not fully reliable yet, so don't be discouraged if the test fails. Here is the github repo of the source of the tester, where you can file bug reports.

- There is a WebRTC test tool at https://webrtc.github.io/samples/src/content/peerconnection/trickle-ice/. To use it, you will need a username/password for your TURN server. You can either:

  - look for the `GET /_matrix/client/r0/voip/turnServer` request made by a matrix client to your homeserver in your browser's network inspector. In the response you should see `username` and `password`. Or:

  - Use the following shell commands:

        secret=staticAuthSecretHere

        u=$((`date +%s` + 3600)):test
        p=$(echo -n $u | openssl dgst -hmac $secret -sha1 -binary | base64)
        echo -e "username: $u\npassword: $p"

    Or:

  - Temporarily configure coturn to accept a static username/password. To do this, comment out `use-auth-secret` and `static-auth-secret` and add the following:

        lt-cred-mech
        user=username:password

    Note: these settings will not take effect unless `use-auth-secret` and `static-auth-secret` are disabled.

    Restart coturn after changing the configuration file.

    Remember to restore the original settings to go back to testing with Matrix clients!

  If the TURN server is working correctly, you should see at least one `relay` entry in the results.

# Delegation

By default, other homeservers will expect to be able to reach yours via your `server_name`, on port 8448. For example, if you set your `server_name` to `example.com` (so that your user names look like `@user:example.com`), other servers will try to connect to yours at `https://example.com:8448/`.

Delegation is a Matrix feature allowing a homeserver admin to retain a `server_name` of `example.com` so that user IDs, room aliases, etc continue to look like `*:example.com`, whilst having federation traffic routed to a different server and/or port (e.g. `synapse.example.com:443`).

## .well-known delegation

To use this method, you need to be able to alter the `server_name` 's https server to serve the `/.well-known/matrix/server` URL. Having an active server (with a valid TLS certificate) serving your `server_name` domain is out of the scope of this documentation.

The URL `https://<server_name>/.well-known/matrix/server` should return a JSON structure containing the key `m.server` like so:

    {
        "m.server": "<synapse.server.name>[:<yourport>]"
    }

In our example, this would mean that URL `https://example.com/.well-known/matrix/server` should return:

    {
        "m.server": "synapse.example.com:443"
    }

Note, specifying a port is optional. If no port is specified, then it defaults to 8448.

With .well-known delegation, federating servers will check for a valid TLS certificate for the delegated hostname (in our example: `synapse.example.com`).

## SRV DNS record delegation

It is also possible to do delegation using a SRV DNS record. However, that is considered an advanced topic since it's a bit complex to set up, and `.well-known` delegation is already enough in most cases.

However, if you really need it, you can find some documentation on how such a record should look like and how Synapse will use it in the Matrix specification.

## Delegation FAQ

### When do I need delegation?

If your homeserver's APIs are accessible on the default federation port (8448) and the domain your `server_name` points to, you do not need any delegation.

For instance, if you registered `example.com` and pointed its DNS A record at a fresh server, you could install Synapse on that host, giving it a `server_name` of `example.com`, and once a reverse proxy has been set up to proxy all requests sent to the port `8448` and serve TLS certificates for `example.com`, you wouldn't need any delegation set up.

However, if your homeserver's APIs aren't accessible on port 8448 and on the domain `server_name` points to, you will need to let other servers know how to find it using delegation.

### Do you still recommend against using a reverse proxy on the federation port?

We no longer actively recommend against using a reverse proxy. Many admins will find it easier to direct federation traffic to a reverse proxy and manage their own TLS certificates, and this is a supported configuration.

See the reverse proxy documentation for information on setting up a reverse proxy.

### Do I still need to give my TLS certificates to Synapse if I am using a reverse proxy?

This is no longer necessary. If you are using a reverse proxy for all of your TLS traffic, then you can set `no_tls: True` in the Synapse config.

In that case, the only reason Synapse needs the certificate is to populate a legacy `tls_fingerprints` field in the federation API. This is ignored by Synapse 0.99.0 and later, and the only time pre-0.99 Synapses will check it is when attempting to fetch the server keys - and generally this is delegated via `matrix.org`, which is running a modern version of Synapse.

### Do I need the same certificate for the client and federation port?

No. There is nothing stopping you from using different certificates, particularly if you are using a reverse proxy.

# Upgrading Synapse

Before upgrading check if any special steps are required to upgrade from the version you currently have installed to the current version of Synapse. The extra instructions that may be required are listed later in this document.

- Check that your versions of Python and PostgreSQL are still supported.

  Synapse follows upstream lifecycles for Python and PostgreSQL, and removes support for versions which are no longer maintained.

  The website https://endoflife.date also offers convenient summaries.

- If Synapse was installed using prebuilt packages, you will need to follow the normal process for upgrading those packages.

- If Synapse was installed from source, then:

  1. Activate the virtualenv before upgrading. For example, if Synapse is installed in a virtualenv in `~/synapse/env` then run:

         source ~/synapse/env/bin/activate

  2. If Synapse was installed using pip then upgrade to the latest version by running:

         pip install --upgrade matrix-synapse

     If Synapse was installed using git then upgrade to the latest version by running:

         git pull
         pip install --upgrade .

  3. Restart Synapse:

         ./synctl restart

To check whether your update was successful, you can check the running server version with:

    # you may need to replace 'localhost:8008' if synapse is not configured
    # to listen on port 8008.

    curl http://localhost:8008/_synapse/admin/v1/server_version

## Rolling back to older versions

Rolling back to previous releases can be difficult, due to database schema changes between releases. Where we have been able to test the rollback process, this will be noted below.

In general, you will need to undo any changes made during the upgrade process, for example:

- pip:

      source env/bin/activate
      # replace `1.3.0` accordingly:
      pip install matrix-synapse==1.3.0

- Debian:

      # replace `1.3.0` and `stretch` accordingly:
      wget https://packages.matrix.org/debian/pool/main/m/matrix-synapse-py3/matrix-synapse-py3_1.3.0+stretch1_amd64.deb
      dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb

# Upgrading to v1.45.0

## Changes required to media storage provider modules when reading from the Synapse configuration object

Media storage provider modules that read from the Synapse configuration object (i.e. that read the value of `hs.config.[...]`) now need to specify the configuration section they're reading from. This means that if a module reads the value of e.g. `hs.config.media_store_path`, it needs to replace it with `hs.config.media.media_store_path`.

# Upgrading to v1.44.0

## The URL preview cache is no longer mirrored to storage providers

The `url_cache/` and `url_cache_thumbnails/` directories in the media store are no longer mirrored to storage providers. These two directories can be safely deleted from any configured storage providers to reclaim space.

# Upgrading to v1.43.0

## The spaces summary APIs can now be handled by workers

The available worker applications documentation has been updated to reflect that calls to the `/spaces`, `/hierarchy`, and `/summary` endpoints can now be routed to workers for both client API and federation requests.

# Upgrading to v1.42.0

## Removal of old Room Admin API

The following admin APIs were deprecated in Synapse 1.25 (released on 2021-01-13) and have now been removed:

- `POST /_synapse/admin/v1/purge_room`
- `POST /_synapse/admin/v1/shutdown_room/<room_id>`

Any scripts still using the above APIs should be converted to use the Delete Room API.

## User-interactive authentication fallback templates can now display errors

This may affect you if you make use of custom HTML templates for the reCAPTCHA or terms fallback pages.

The template is now provided an `error` variable if the authentication process failed. See the default templates linked above for an example.

## Removal of out-of-date email pushers

Users will stop receiving message updates via email for addresses that were once, but not still, linked to their account.

# Upgrading to v1.41.0

## Add support for routing outbound HTTP requests via a proxy for federation

Since Synapse 1.6.0 (2019-11-26) you can set a proxy for outbound HTTP requests via http_proxy/https_proxy environment variables. This proxy was set for:

- push
- url previews
- phone-home stats
- recaptcha validation
- CAS auth validation
- OpenID Connect
- Federation (checking public key revocation)

In this version we have added support for outbound requests for:

- Outbound federation
- Downloading remote media
- Fetching public keys of other servers

These requests use the same proxy configuration. If you have a proxy configuration we recommend to verify the configuration. It may be necessary to adjust the `no_proxy` environment variable.

See using a forward proxy with Synapse documentation for details.

## Deprecation of `template_dir`

The `template_dir` settings in the `sso`, `account_validity` and `email` sections of the configuration file are now deprecated. Server admins should use the new `templates.custom_template_directory` setting in the configuration file and use one single custom template directory for all aforementioned features. Template file names remain unchanged. See the related documentation for more information and examples.

We plan to remove support for these settings in October 2021.

## `/_synapse/admin/v1/users/{userId}/media` must be handled by media workers

The media repository worker documentation has been updated to reflect that calls to `/_synapse/admin/v1/users/{userId}/media` must now be handled by media repository workers. This is due to the new `DELETE` method of this endpoint modifying the media store.

# Upgrading to v1.39.0

## Deprecation of the current third-party rules module interface

The current third-party rules module interface is deprecated in favour of the new generic modules system introduced in Synapse v1.37.0. Authors of third-party rules modules can refer to this documentation to update their modules. Synapse administrators can refer to this documentation to update their configuration once the modules they are using have been updated.

We plan to remove support for the current third-party rules interface in September 2021.

# Upgrading to v1.38.0

## Re-indexing of `events` table on Postgres databases

This release includes a database schema update which requires re-indexing one of the larger tables in the database, `events`. This could result in increased disk I/O for several hours or days after upgrading while the migration completes. Furthermore, because we have to keep the old indexes until the new indexes are ready, it could result in a significant, temporary, increase in disk space.

To get a rough idea of the disk space required, check the current size of one of the indexes. For example, from a `psql` shell, run the following sql:

    SELECT pg_size_pretty(pg_relation_size('events_order_room'));

We need to rebuild four indexes, so you will need to multiply this result by four to give an estimate of the disk space required. For example, on one particular server:

    synapse=# select pg_size_pretty(pg_relation_size('events_order_room'));
     pg_size_pretty
    ----------------
     288 MB
    (1 row)

On this server, it would be wise to ensure that at least 1152MB are free.

The additional disk space will be freed once the migration completes.

SQLite databases are unaffected by this change.

# Upgrading to v1.37.0

## Deprecation of the current spam checker interface

The current spam checker interface is deprecated in favour of a new generic modules system. Authors of spam checker modules can refer to [this documentation](modules/porting_legacy_module.md to update their modules. Synapse administrators can refer to this documentation to update their configuration once the modules they are using have been updated.

We plan to remove support for the current spam checker interface in August 2021.

More module interfaces will be ported over to this new generic system in future versions of Synapse.

# Upgrading to v1.34.0

## `room_invite_state_types` configuration setting

The `room_invite_state_types` configuration setting has been deprecated and replaced with `room_prejoin_state`. See the sample configuration file.

If you have set `room_invite_state_types` to the default value you should simply remove it from your configuration file. The default value used to be:

    room_invite_state_types:
       - "m.room.join_rules"
       - "m.room.canonical_alias"
       - "m.room.avatar"
       - "m.room.encryption"
       - "m.room.name"

If you have customised this value, you should remove `room_invite_state_types` and configure `room_prejoin_state` instead.

# Upgrading to v1.33.0

## Account Validity HTML templates can now display a user's expiration date

This may affect you if you have enabled the account validity feature, and have made use of a custom HTML template specified by the `account_validity.template_dir` or `account_validity.account_renewed_html_path` Synapse config options.

The template can now accept an `expiration_ts` variable, which represents the unix timestamp in milliseconds for the future date of which their account has been renewed until. See the default template for an example of usage.

ALso note that a new HTML template, `account_previously_renewed.html`, has been added. This is is shown to users when they attempt to renew their account with a valid renewal token that has already been used before. The default template contents can been found here, and can also accept an `expiration_ts` variable. This template replaces the error message users would previously see upon attempting to use a valid renewal token more than once.

# Upgrading to v1.32.0

## Regression causing connected Prometheus instances to become overwhelmed

This release introduces a regression that can overwhelm connected Prometheus instances. This issue is not present in Synapse v1.32.0rc1.

If you have been affected, please downgrade to 1.31.0. You then may need to remove excess writeahead logs in order for Prometheus to recover. Instructions for doing so are provided here.

## Dropping support for old Python, Postgres and SQLite versions

In line with our deprecation policy, we've dropped support for Python 3.5 and PostgreSQL 9.5, as they are no longer supported upstream.

This release of Synapse requires Python 3.6+ and PostgresSQL 9.6+ or SQLite 3.22+.

## Removal of old List Accounts Admin API

The deprecated v1 "list accounts" admin API (`GET /_synapse/admin/v1/users/<user_id>`) has been removed in this version.

The v2 list accounts API has been available since Synapse 1.7.0 (2019-12-13), and is accessible under `GET /_synapse/admin/v2/users`.

The deprecation of the old endpoint was announced with Synapse 1.28.0 (released on 2021-02-25).

## Application Services must use type `m.login.application_service` when registering users

In compliance with the Application Service spec, Application Services are now required to use the `m.login.application_service` type when registering users via the `/_matrix/client/r0/register` endpoint. This behaviour was deprecated in Synapse v1.30.0.

Please ensure your Application Services are up to date.

# Upgrading to v1.29.0

## Requirement for X-Forwarded-Proto header

When using Synapse with a reverse proxy (in particular, when using the `x_forwarded` option on an HTTP listener), Synapse now expects to receive an `X-Forwarded-Proto` header on incoming HTTP requests. If it is not set, Synapse will log a warning on each received request.

To avoid the warning, administrators using a reverse proxy should ensure that the reverse proxy sets `X-Forwarded-Proto` header to `https` or `http` to indicate the protocol used by the client.

Synapse also requires the `Host` header to be preserved.

See the reverse proxy documentation, where the example configurations have been updated to show how to set these headers.

(Users of Caddy are unaffected, since we believe it sets `X-Forwarded-Proto` by default.)

# Upgrading to v1.27.0

## Changes to callback URI for OAuth2 / OpenID Connect and SAML2

This version changes the URI used for callbacks from OAuth2 and SAML2 identity providers:

- If your server is configured for single sign-on via an OpenID Connect or OAuth2 identity provider, you will need to add `[synapse public baseurl]/_synapse/client/oidc/callback` to the list of permitted "redirect URIs" at the identity provider.

  See the OpenID docs for more information on setting up OpenID Connect.

- If your server is configured for single sign-on via a SAML2 identity provider, you will need to add `[synapse public baseurl]/_synapse/client/saml2/authn_response` as a permitted "ACS location" (also known as "allowed callback URLs") at the identity provider.

  The "Issuer" in the "AuthnRequest" to the SAML2 identity provider is also updated to `[synapse public baseurl]/_synapse/client/saml2/metadata.xml`. If your SAML2 identity provider uses this property to validate or otherwise identify Synapse, its configuration will need to be updated to use the new URL. Alternatively you could create a new, separate "EntityDescriptor" in your SAML2 identity provider with the new URLs and leave the URLs in the existing "EntityDescriptor" as they were.

## Changes to HTML templates

The HTML templates for SSO and email notifications now have Jinja2's autoescape enabled for files ending in `.html`, `.htm`, and `.xml`. If you have customised these templates and see issues when viewing them you might need to update them. It is expected that most configurations will need no changes.

If you have customised the templates names for these templates, it is recommended to verify they end in `.html` to ensure autoescape is enabled.

The above applies to the following templates:

- `add_threepid.html`
- `add_threepid_failure.html`
- `add_threepid_success.html`
- `notice_expiry.html`
- `notice_expiry.html`
- `notif_mail.html` (which, by default, includes `room.html` and `notif.html`)
- `password_reset.html`
- `password_reset_confirmation.html`
- `password_reset_failure.html`
- `password_reset_success.html`
- `registration.html`
- `registration_failure.html`
- `registration_success.html`
- `sso_account_deactivated.html`
- `sso_auth_bad_user.html`
- `sso_auth_confirm.html`
- `sso_auth_success.html`
- `sso_error.html`
- `sso_login_idp_picker.html`
- `sso_redirect_confirm.html`

# Upgrading to v1.26.0

## Rolling back to v1.25.0 after a failed upgrade

v1.26.0 includes a lot of large changes. If something problematic occurs, you may want to roll-back to a previous version of Synapse. Because v1.26.0 also includes a new database schema version, reverting that version is also required alongside the generic rollback instructions mentioned above. In short, to roll back to v1.25.0 you need to:

1. Stop the server

2. Decrease the schema version in the database:

       UPDATE schema_version SET version = 58;

3. Delete the ignored users & chain cover data:

       DROP TABLE IF EXISTS ignored_users;
       UPDATE rooms SET has_auth_chain_index = false;

   For PostgreSQL run:

       TRUNCATE event_auth_chain_links;
       TRUNCATE event_auth_chains;

   For SQLite run:

       DELETE FROM event_auth_chain_links;
       DELETE FROM event_auth_chains;

4. Mark the deltas as not run (so they will re-run on upgrade).

       DELETE FROM applied_schema_deltas WHERE version = 59 AND file = "59/01ignored_user.py";
       DELETE FROM applied_schema_deltas WHERE version = 59 AND file = "59/06chain_cover_index.sql";

5. Downgrade Synapse by following the instructions for your installation method in the "Rolling back to older versions" section above.

# Upgrading to v1.25.0

## Last release supporting Python 3.5

This is the last release of Synapse which guarantees support with Python 3.5, which passed its upstream End of Life date several months ago.

We will attempt to maintain support through March 2021, but without guarantees.

In the future, Synapse will follow upstream schedules for ending support of older versions of Python and PostgreSQL. Please upgrade to at least Python 3.6 and PostgreSQL 9.6 as soon as possible.

## Blacklisting IP ranges

Synapse v1.25.0 includes new settings, `ip_range_blacklist` and `ip_range_whitelist`, for controlling outgoing requests from Synapse for federation, identity servers, push, and for checking key validity for third-party invite events. The previous setting, `federation_ip_range_blacklist`, is deprecated. The new `ip_range_blacklist` defaults to private IP ranges if it is not defined.

If you have never customised `federation_ip_range_blacklist` it is recommended that you remove that setting.

If you have customised `federation_ip_range_blacklist` you should update the setting name to `ip_range_blacklist`.

If you have a custom push server that is reached via private IP space you may need to customise `ip_range_blacklist` or `ip_range_whitelist`.

# Upgrading to v1.24.0

## Custom OpenID Connect mapping provider breaking change

This release allows the OpenID Connect mapping provider to perform normalisation of the localpart of the Matrix ID. This allows for the mapping provider to specify different algorithms, instead of the default way.

If your Synapse configuration uses a custom mapping provider (`oidc_config.user_mapping_provider.module` is specified and not equal to `synapse.handlers.oidc_handler.JinjaOidcMappingProvider`) then you must ensure that `map_user_attributes` of the mapping provider performs some normalisation of the `localpart` returned. To match previous behaviour you can use the `map_username_to_mxid_localpart` function provided by Synapse. An example is shown below:

    from synapse.types import map_username_to_mxid_localpart

    class MyMappingProvider:
        def map_user_attributes(self, userinfo, token):
            # ... your custom logic ...
            sso_user_id = ...
            localpart = map_username_to_mxid_localpart(sso_user_id)

            return {"localpart": localpart}

## Removal historical Synapse Admin API

Historically, the Synapse Admin API has been accessible under:

- `/_matrix/client/api/v1/admin`
- `/_matrix/client/unstable/admin`
- `/_matrix/client/r0/admin`
- `/_synapse/admin/v1`

The endpoints with `/_matrix/client/*` prefixes have been removed as of v1.24.0. The Admin API is now only accessible under:

- `/_synapse/admin/v1`

The only exception is the `/admin/whois` endpoint, which is also available via the client-server API.

The deprecation of the old endpoints was announced with Synapse 1.20.0 (released on 2020-09-22) and makes it easier for homeserver admins to lock down external access to the Admin API endpoints.

# Upgrading to v1.23.0

## Structured logging configuration breaking changes

This release deprecates use of the `structured: true` logging configuration for structured logging. If your logging configuration contains `structured: true` then it should be modified based on the structured logging documentation.

The `structured` and `drains` logging options are now deprecated and should be replaced by standard logging configuration of `handlers` and `formatters`.

A future will release of Synapse will make using `structured: true` an error.

# Upgrading to v1.22.0

## ThirdPartyEventRules breaking changes

This release introduces a backwards-incompatible change to modules making use of `ThirdPartyEventRules` in Synapse. If you make use of a module defined under the `third_party_event_rules` config option, please make sure it is updated to handle the below change:

The `http_client` argument is no longer passed to modules as they are initialised. Instead, modules are expected to make use of the `http_client` property on the `ModuleApi` class. Modules are now passed a `module_api` argument during initialisation, which is an instance of `ModuleApi`. `ModuleApi` instances have a `http_client` property which acts the same as the `http_client` argument previously passed to `ThirdPartyEventRules` modules.

# Upgrading to v1.21.0

## Forwarding `/_synapse/client` through your reverse proxy

The reverse proxy documentation has been updated to include reverse proxy directives for `/_synapse/client/*` endpoints. As the user password reset flow now uses endpoints under this prefix, you must update your reverse proxy configurations for user password reset to work.

Additionally, note that the Synapse worker documentation has been updated to

: state that the `/_synapse/client/password_reset/email/submit_token` endpoint can be handled

by all workers. If you make use of Synapse's worker feature, please update your reverse proxy configuration to reflect this change.

## New HTML templates

A new HTML template, password_reset_confirmation.html, has been added to the `synapse/res/templates` directory. If you are using a custom template directory, you may want to copy the template over and modify it.

Note that as of v1.20.0, templates do not need to be included in custom template directories for Synapse to start. The default templates will be used if a custom template cannot be found.

This page will appear to the user after clicking a password reset link that has been emailed to them.

To complete password reset, the page must include a way to make a `POST` request to `/_synapse/client/password_reset/{medium}/submit_token` with the query parameters from the original link, presented as a URL-encoded form. See the file itself for more details.

## Updated Single Sign-on HTML Templates

The `saml_error.html` template was removed from Synapse and replaced with the `sso_error.html` template. If your Synapse is configured to use SAML and a custom `sso_redirect_confirm_template_dir` configuration then any customisations of the `saml_error.html` template will need to be merged into the `sso_error.html` template. These templates are similar, but the parameters are slightly different:

- The `msg` parameter should be renamed to `error_description`.
- There is no longer a `code` parameter for the response code.
- A string `error` parameter is available that includes a short hint of why a user is seeing the error page.

# Upgrading to v1.18.0

## Docker `-py3` suffix will be removed in future versions

From 10th August 2020, we will no longer publish Docker images with the `-py3` tag suffix. The images tagged with the `-py3` suffix have been identical to the non-suffixed tags since release 0.99.0, and the suffix is obsolete.

On 10th August, we will remove the `latest-py3` tag. Existing per-release tags (such as `v1.18.0-py3` will not be removed, but no new `-py3` tags will be added.

Scripts relying on the `-py3` suffix will need to be updated.

## Redis replication is now recommended in lieu of TCP replication

When setting up worker processes, we now recommend the use of a Redis server for replication. The old direct TCP connection method is deprecated and will be removed in a future release. See workers for more details.

# Upgrading to v1.14.0

This version includes a database update which is run as part of the upgrade, and which may take a couple of minutes in the case of a large server. Synapse will not respond to HTTP requests while this update is taking place.

# Upgrading to v1.13.0

## Incorrect database migration in old synapse versions

A bug was introduced in Synapse 1.4.0 which could cause the room directory to be incomplete or empty if Synapse was upgraded directly from v1.2.1 or earlier, to versions between v1.4.0 and v1.12.x.

This will not be a problem for Synapse installations which were:

: - created at v1.4.0 or later, - upgraded via v1.3.x, or - upgraded straight from v1.2.1 or earlier to v1.13.0 or later.

If completeness of the room directory is a concern, installations which are affected can be repaired as follows:

1. Run the following sql from a `psql` or `sqlite3` console:

       INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
          ('populate_stats_process_rooms', '{}', 'current_state_events_membership');

       INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
          ('populate_stats_process_users', '{}', 'populate_stats_process_rooms');

2. Restart synapse.

## New Single Sign-on HTML Templates

New templates (`sso_auth_confirm.html`, `sso_auth_success.html`, and `sso_account_deactivated.html`) were added to Synapse. If your Synapse is configured to use SSO and a custom `sso_redirect_confirm_template_dir` configuration then these templates will need to be copied from synapse/res/templates into that directory.

## Synapse SSO Plugins Method Deprecation

Plugins using the `complete_sso_login` method of `synapse.module_api.ModuleApi` should update to using the async/await version `complete_sso_login_async` which includes additional checks. The non-async version is considered deprecated.

## Rolling back to v1.12.4 after a failed upgrade

v1.13.0 includes a lot of large changes. If something problematic occurs, you may want to roll-back to a previous version of Synapse. Because v1.13.0 also includes a new database schema version, reverting that version is also required alongside the generic rollback instructions mentioned above. In short, to roll back to v1.12.4 you need to:

1. Stop the server

2. Decrease the schema version in the database:

       UPDATE schema_version SET version = 57;

3. Downgrade Synapse by following the instructions for your installation method in the "Rolling back to older versions" section above.

# Upgrading to v1.12.0

This version includes a database update which is run as part of the upgrade, and which may take some time (several hours in the case of a large server). Synapse will not respond to HTTP requests while this update is taking place.

This is only likely to be a problem in the case of a server which is participating in many rooms.

0. As with all upgrades, it is recommended that you have a recent backup of your database which can be used for recovery in the event of any problems.

1. As an initial check to see if you will be affected, you can try running the following query from the `psql` or `sqlite3` console. It is safe to run it while Synapse is still running.

       SELECT MAX(q.v) FROM (
         SELECT (
           SELECT ej.json AS v
           FROM state_events se INNER JOIN event_json ej USING (event_id)
           WHERE se.room_id=rooms.room_id AND se.type='m.room.create' AND se.state_key=''
           LIMIT 1
         ) FROM rooms WHERE rooms.room_version IS NULL
       ) q;

   This query will take about the same amount of time as the upgrade process: ie, if it takes 5 minutes, then it is likely that Synapse will be unresponsive for 5 minutes during the upgrade.

   If you consider an outage of this duration to be acceptable, no further action is necessary and you can simply start Synapse 1.12.0.

   If you would prefer to reduce the downtime, continue with the steps below.

2. The easiest workaround for this issue is to manually create a new index before upgrading. On PostgreSQL, his can be done as follows:

       CREATE INDEX CONCURRENTLY tmp_upgrade_1_12_0_index
       ON state_events(room_id) WHERE type = 'm.room.create';

   The above query may take some time, but is also safe to run while Synapse is running.

   We assume that no SQLite users have databases large enough to be affected. If you are affected, you can run a similar query, omitting the `CONCURRENTLY` keyword. Note however that this operation may in itself cause Synapse to stop running for some time. Synapse admins are reminded that SQLite is not recommended for use outside a test environment.

3. Once the index has been created, the `SELECT` query in step 1 above should complete quickly. It is therefore safe to upgrade to Synapse 1.12.0.

4. Once Synapse 1.12.0 has successfully started and is responding to HTTP requests, the temporary index can be removed:

       DROP INDEX tmp_upgrade_1_12_0_index;

# Upgrading to v1.10.0

Synapse will now log a warning on start up if used with a PostgreSQL database that has a non-recommended locale set.

See Postgres for details.

# Upgrading to v1.8.0

Specifying a `log_file` config option will now cause Synapse to refuse to start, and should be replaced by with the `log_config` option. Support for the `log_file` option was removed in v1.3.0 and has since had no effect.

# Upgrading to v1.7.0

In an attempt to configure Synapse in a privacy preserving way, the default behaviours of `allow_public_rooms_without_auth` and `allow_public_rooms_over_federation` have been inverted. This means that by default, only authenticated users querying the Client/Server API will be able to query the room directory, and relatedly that the server will not share room directory information with other servers over federation.

If your installation does not explicitly set these settings one way or the other and you want either setting to be `true` then it will necessary to update your homeserver configuration file accordingly.

For more details on the surrounding context see our explainer.

# Upgrading to v1.5.0

This release includes a database migration which may take several minutes to complete if there are a large number (more than a million or so) of entries in the `devices` table. This is only likely to a be a problem on very large installations.

# Upgrading to v1.4.0

## New custom templates

If you have configured a custom template directory with the `email.template_dir` option, be aware that there are new templates regarding registration and threepid management (see below) that must be included.

- `registration.html` and `registration.txt`
- `registration_success.html` and `registration_failure.html`
- `add_threepid.html` and `add_threepid.txt`
- `add_threepid_failure.html` and `add_threepid_success.html`

Synapse will expect these files to exist inside the configured template directory, and will fail to start if they are absent. To view the default templates, see synapse/res/templates.

## 3pid verification changes

Note: As of this release, users will be unable to add phone numbers or email addresses to their accounts, without changes to the Synapse configuration. This includes adding an email address during registration.

It is possible for a user to associate an email address or phone number with their account, for a number of reasons:

- for use when logging in, as an alternative to the user id.
- in the case of email, as an alternative contact to help with account recovery.
- in the case of email, to receive notifications of missed messages.

Before an email address or phone number can be added to a user's account, or before such an address is used to carry out a password-reset, Synapse must confirm the operation with the owner of the email address or phone number. It does this by sending an email or text giving the user a link or token to confirm receipt. This process is known as '3pid verification'. ('3pid', or 'threepid', stands for third-party identifier, and we use it to refer to external identifiers such as email addresses and phone numbers.)

Previous versions of Synapse delegated the task of 3pid verification to an identity server by default. In most cases this server is `vector.im` or `matrix.org`.

In Synapse 1.4.0, for security and privacy reasons, the homeserver will no longer delegate this task to an identity server by default. Instead, the server administrator will need to explicitly decide how they would like the verification messages to be sent.

In the medium term, the `vector.im` and `matrix.org` identity servers will disable support for delegated 3pid verification entirely. However, in order to ease the transition, they will retain the capability for a limited period. Delegated email verification will be disabled on Monday 2nd December 2019 (giving roughly 2 months notice). Disabling delegated SMS verification will follow some time after that once SMS verification support lands in Synapse.

Once delegated 3pid verification support has been disabled in the `vector.im` and `matrix.org` identity servers, all Synapse versions that depend on those instances will be unable to verify email and phone numbers through them. There are no imminent plans to remove delegated 3pid verification from Sydent generally. (Sydent is the identity server project that backs the `vector.im` and `matrix.org` instances).

### Email

Following upgrade, to continue verifying email (e.g. as part of the registration process), admins can either:-

- Configure Synapse to use an email server.
- Run or choose an identity server which allows delegated email verification and delegate to it.

#### Configure SMTP in Synapse

To configure an SMTP server for Synapse, modify the configuration section headed `email`, and be sure to have at least the `smtp_host, smtp_port` and `notif_from` fields filled out.

You may also need to set `smtp_user`, `smtp_pass`, and `require_transport_security`.

See the sample configuration file for more details on these settings.

#### Delegate email to an identity server

Some admins will wish to continue using email verification as part of the registration process, but will not immediately have an appropriate SMTP server at hand.

To this end, we will continue to support email verification delegation via the `vector.im` and `matrix.org` identity servers for two months. Support for delegated email verification will be disabled on Monday 2nd December.

The `account_threepid_delegates` dictionary defines whether the homeserver should delegate an external server (typically an identity server) to handle sending confirmation messages via email and SMS.

So to delegate email verification, in `homeserver.yaml`, set `account_threepid_delegates.email` to the base URL of an identity server. For example:

    account_threepid_delegates:
        email: https://example.com     # Delegate email sending to example.com

Note that `account_threepid_delegates.email` replaces the deprecated `email.trust_identity_server_for_password_resets`: if `email.trust_identity_server_for_password_resets` is set to `true`, and `account_threepid_delegates.email` is not set, then the first entry in `trusted_third_party_id_servers` will be used as the `account_threepid_delegate` for email. This is to ensure compatibility with existing Synapse installs that set up external server handling for these tasks before v1.4.0. If `email.trust_identity_server_for_password_resets` is `true` and no trusted identity server domains are configured, Synapse will report an error and refuse to start.

If `email.trust_identity_server_for_password_resets` is `false` or absent and no `email` delegate is configured in `account_threepid_delegates`, then Synapse will send email verification messages itself, using the configured SMTP server (see above). that type.

### Phone numbers

Synapse does not support phone-number verification itself, so the only way to maintain the ability for users to add phone numbers to their accounts will be by continuing to delegate phone number verification to the `matrix.org` and `vector.im` identity servers (or another identity server that supports SMS sending).

The `account_threepid_delegates` dictionary defines whether the homeserver should delegate an external server (typically an identity server) to handle sending confirmation messages via email and SMS.

So to delegate phone number verification, in `homeserver.yaml`, set `account_threepid_delegates.msisdn` to the base URL of an identity server. For example:

    account_threepid_delegates:
        msisdn: https://example.com     # Delegate sms sending to example.com

The `matrix.org` and `vector.im` identity servers will continue to support delegated phone number verification via SMS until such time as it is possible for admins to configure their servers to perform phone number verification directly. More details will follow in a future release.

## Rolling back to v1.3.1

If you encounter problems with v1.4.0, it should be possible to roll back to v1.3.1, subject to the following:

- The 'room statistics' engine was heavily reworked in this release (see #5971), including significant changes to the database schema, which are not easily reverted. This will cause the room statistics engine to stop updating when you downgrade.

  The room statistics are essentially unused in v1.3.1 (in future versions of Synapse, they will be used to populate the room directory), so there should be no loss of functionality. However, the statistics engine will write errors to the logs, which can be avoided by setting the following in `homeserver.yaml`:

      stats:
        enabled: false

  Don't forget to re-enable it when you upgrade again, in preparation for its use in the room directory!

# Upgrading to v1.2.0

Some counter metrics have been renamed, with the old names deprecated. See the metrics documentation for details.

# Upgrading to v1.1.0

Synapse v1.1.0 removes support for older Python and PostgreSQL versions, as outlined in our deprecation notice.

## Minimum Python Version

Synapse v1.1.0 has a minimum Python requirement of Python 3.5. Python 3.6 or Python 3.7 are recommended as they have improved internal string handling, significantly reducing memory usage.

If you use current versions of the Matrix.org-distributed Debian packages or Docker images, action is not required.

If you install Synapse in a Python virtual environment, please see "Upgrading to v0.34.0" for notes on setting up a new virtualenv under Python 3.

## Minimum PostgreSQL Version

If using PostgreSQL under Synapse, you will need to use PostgreSQL 9.5 or above. Please see the PostgreSQL documentation for more details on upgrading your database.

# Upgrading to v1.0

## Validation of TLS certificates

Synapse v1.0 is the first release to enforce validation of TLS certificates for the federation API. It is therefore essential that your certificates are correctly configured. See the FAQ for more information.

Note, v1.0 installations will also no longer be able to federate with servers that have not correctly configured their certificates.

In rare cases, it may be desirable to disable certificate checking: for example, it might be essential to be able to federate with a given legacy server in a closed federation. This can be done in one of two ways:-

- Configure the global switch `federation_verify_certificates` to `false`.
- Configure a whitelist of server domains to trust via `federation_certificate_verification_whitelist`.

See the sample configuration file for more details on these settings.

## Email

When a user requests a password reset, Synapse will send an email to the user to confirm the request.

Previous versions of Synapse delegated the job of sending this email to an identity server. If the identity server was somehow malicious or became compromised, it would be theoretically possible to hijack an account through this means.

Therefore, by default, Synapse v1.0 will send the confirmation email itself. If Synapse is not configured with an SMTP server, password reset via email will be disabled.

To configure an SMTP server for Synapse, modify the configuration section headed `email`, and be sure to have at least the `smtp_host`, `smtp_port` and `notif_from` fields filled out. You may also need to set `smtp_user`, `smtp_pass`, and `require_transport_security`.

If you are absolutely certain that you wish to continue using an identity server for password resets, set `trust_identity_server_for_password_resets` to `true`.

See the sample configuration file for more details on these settings.

## New email templates

Some new templates have been added to the default template directory for the purpose of the homeserver sending its own password reset emails. If you have configured a custom `template_dir` in your Synapse config, these files will need to be added.

`password_reset.html` and `password_reset.txt` are HTML and plain text templates respectively that contain the contents of what will be emailed to the user upon attempting to reset their password via email. `password_reset_success.html` and `password_reset_failure.html` are HTML files that the content of which (assuming no redirect URL is set) will be shown to the user after they attempt to click the link in the email sent to them.

# Upgrading to v0.99.0

Please be aware that, before Synapse v1.0 is released around March 2019, you will need to replace any self-signed certificates with those verified by a root CA. Information on how to do so can be found at the ACME docs.

For more information on configuring TLS certificates see the FAQ.

# Upgrading to v0.34.0

1. This release is the first to fully support Python 3. Synapse will now run on Python versions 3.5, or 3.6 (as well as 2.7). We recommend switching to Python 3, as it has been shown to give performance improvements.

   For users who have installed Synapse into a virtualenv, we recommend doing this by creating a new virtualenv. For example:

       virtualenv -p python3 ~/synapse/env3
       source ~/synapse/env3/bin/activate
       pip install matrix-synapse

   You can then start synapse as normal, having activated the new virtualenv:

       cd ~/synapse
       source env3/bin/activate
       synctl start

   Users who have installed from distribution packages should see the relevant package documentation. See below for notes on Debian packages.

   - When upgrading to Python 3, you must make sure that your log files are configured as UTF-8, by adding `encoding: utf8` to the `RotatingFileHandler` configuration (if you have one) in your `<server>.log.config` file. For example, if your `log.config` file contains:

         handlers:
           file:
             class: logging.handlers.RotatingFileHandler
             formatter: precise
             filename: homeserver.log
             maxBytes: 104857600
             backupCount: 10
             filters: [context]
           console:
             class: logging.StreamHandler
             formatter: precise
             filters: [context]

     Then you should update this to be:

         handlers:
           file:
             class: logging.handlers.RotatingFileHandler
             formatter: precise
             filename: homeserver.log
             maxBytes: 104857600
             backupCount: 10
             filters: [context]
             encoding: utf8
           console:
             class: logging.StreamHandler
             formatter: precise
             filters: [context]

     There is no need to revert this change if downgrading to Python 2.

   We are also making available Debian packages which will run Synapse on Python 3. You can switch to these packages with `apt-get install matrix-synapse-py3`, however, please read debian/NEWS before doing so. The existing `matrix-synapse` packages will continue to use Python 2 for the time being.

2. This release removes the `riot.im` from the default list of trusted identity servers.

   If `riot.im` is in your homeserver's list of `trusted_third_party_id_servers`, you should remove it. It was added in case a hypothetical future identity server was put there. If you don't remove it, users may be unable to deactivate their accounts.

3. This release no longer installs the (unmaintained) Matrix Console web client as part of the default installation. It is possible to re-enable it by installing it separately and setting the `web_client_location` config option, but please consider switching to another client.

# Upgrading to v0.33.7

This release removes the example email notification templates from `res/templates` (they are now internal to the python package). This should only affect you if you (a) deploy your Synapse instance from a git checkout or a github snapshot URL, and (b) have email notifications enabled.

If you have email notifications enabled, you should ensure that `email.template_dir` is either configured to point at a directory where you have installed customised templates, or leave it unset to use the default templates.

# Upgrading to v0.27.3

This release expands the anonymous usage stats sent if the opt-in `report_stats` configuration is set to `true`. We now capture RSS memory and cpu use at a very coarse level. This requires administrators to install the optional `psutil` python module.

We would appreciate it if you could assist by ensuring this module is available and `report_stats` is enabled. This will let us see if performance changes to synapse are having an impact to the general community.

# Upgrading to v0.15.0

If you want to use the new URL previewing API (`/_matrix/media/r0/preview_url`) then you have to explicitly enable it in the config and update your dependencies dependencies. See README.rst for details.

# Upgrading to v0.11.0

This release includes the option to send anonymous usage stats to matrix.org, and requires that administrators explictly opt in or out by setting the `report_stats` option to either `true` or `false`.

We would really appreciate it if you could help our project out by reporting anonymized usage statistics from your homeserver. Only very basic aggregate data (e.g. number of users) will be reported, but it helps us to track the growth of the Matrix community, and helps us to make Matrix a success, as well as to convince other networks that they should peer with us.

# Upgrading to v0.9.0

Application services have had a breaking API change in this version.

They can no longer register themselves with a home server using the AS HTTP API. This decision was made because a compromised application service with free reign to register any regex in effect grants full read/write access to the home server if a regex of `.*` is used. An attack where a compromised AS re-registers itself with `.*` was deemed too big of a security risk to ignore, and so the ability to register with the HS remotely has been removed.

It has been replaced by specifying a list of application service registrations in `homeserver.yaml`:

    app_service_config_files: ["registration-01.yaml", "registration-02.yaml"]

Where `registration-01.yaml` looks like:

    url: <String>  # e.g. "https://my.application.service.com"
    as_token: <String>
    hs_token: <String>
    sender_localpart: <String>  # This is a new field which denotes the user_id localpart when using the AS token
    namespaces:
      users:
        - exclusive: <Boolean>
          regex: <String>  # e.g. "@prefix_.*"
      aliases:
        - exclusive: <Boolean>
          regex: <String>
      rooms:
        - exclusive: <Boolean>
          regex: <String>

# Upgrading to v0.8.0

Servers which use captchas will need to add their public key to:

    static/client/register/register_config.js

      window.matrixRegistrationConfig = {
          recaptcha_public_key: "YOUR_PUBLIC_KEY"
      };

This is required in order to support registration fallback (typically used on mobile devices).

# Upgrading to v0.7.0

New dependencies are:

- pydenticon
- simplejson
- syutil
- matrix-angular-sdk

To pull in these dependencies in a virtual env, run:

    python synapse/python_dependencies.py | xargs -n 1 pip install

# Upgrading to v0.6.0

To pull in new dependencies, run:

    python setup.py develop --user

This update includes a change to the database schema. To upgrade you first need to upgrade the database by running:

    python scripts/upgrade_db_to_v0.6.0.py <db> <server_name> <signing_key>

Where `<db>` is the location of the database, `<server_name>` is the server name as specified in the synapse configuration, and `<signing_key>` is the location of the signing key as specified in the synapse configuration.

This may take some time to complete. Failures of signatures and content hashes can safely be ignored.

# Upgrading to v0.5.1

Depending on precisely when you installed v0.5.0 you may have ended up with a stale release of the reference matrix webclient installed as a python module. To uninstall it and ensure you are depending on the latest module, please run:

    $ pip uninstall syweb

# Upgrading to v0.5.0

The webclient has been split out into a seperate repository/pacakage in this release. Before you restart your homeserver you will need to pull in the webclient package by running:

    python setup.py develop --user

This release completely changes the database schema and so requires upgrading it before starting the new version of the homeserver.

The script "database-prepare-for-0.5.0.sh" should be used to upgrade the database. This will save all user information, such as logins and profiles, but will otherwise purge the database. This includes messages, which rooms the home server was a member of and room alias mappings.

If you would like to keep your history, please take a copy of your database file and ask for help in #matrix:matrix.org. The upgrade process is, unfortunately, non trivial and requires human intervention to resolve any resulting conflicts during the upgrade process.

Before running the command the homeserver should be first completely shutdown. To run it, simply specify the location of the database, e.g.:

> ./scripts/database-prepare-for-0.5.0.sh "homeserver.db"

Once this has successfully completed it will be safe to restart the homeserver. You may notice that the homeserver takes a few seconds longer to restart than usual as it reinitializes the database.

On startup of the new version, users can either rejoin remote rooms using room aliases or by being reinvited. Alternatively, if any other homeserver sends a message to a room that the homeserver was previously in the local HS will automatically rejoin the room.

# Upgrading to v0.4.0

This release needs an updated syutil version. Run:

    python setup.py develop

You will also need to upgrade your configuration as the signing key format has changed. Run:

    python -m synapse.app.homeserver --config-path <CONFIG> --generate-config

# Upgrading to v0.3.0

This registration API now closely matches the login API. This introduces a bit more backwards and forwards between the HS and the client, but this improves the overall flexibility of the API. You can now GET on /register to retrieve a list of valid registration flows. Upon choosing one, they are submitted in the same way as login, e.g:

    {
      type: m.login.password,
      user: foo,
      password: bar
    }

The default HS supports 2 flows, with and without Identity Server email authentication. Enabling captcha on the HS will add in an extra step to all flows: `m.login.recaptcha` which must be completed before you can transition to the next stage. There is a new login type: `m.login.email.identity` which contains the `threepidCreds` key which were previously sent in the original register request. For more information on this, see the specification.

## Web Client

The VoIP specification has changed between v0.2.0 and v0.3.0. Users should refresh any browser tabs to get the latest web client code. Users on v0.2.0 of the web client will not be able to call those on v0.3.0 and vice versa.

# Upgrading to v0.2.0

The home server now requires setting up of SSL config before it can run. To automatically generate default config use:

    $ python synapse/app/homeserver.py \
        --server-name machine.my.domain.name \
        --bind-port 8448 \
        --config-path homeserver.config \
        --generate-config

This config can be edited if desired, for example to specify a different SSL certificate to use. Once done you can run the home server using:

    $ python synapse/app/homeserver.py --config-path homeserver.config

See the README.rst for more information.

Also note that some config options have been renamed, including:

- "host" to "server-name"
- "database" to "database-path"
- "port" to "bind-port" and "unsecure-port"

# Upgrading to v0.0.1

This release completely changes the database schema and so requires upgrading it before starting the new version of the homeserver.

The script "database-prepare-for-0.0.1.sh" should be used to upgrade the database. This will save all user information, such as logins and profiles, but will otherwise purge the database. This includes messages, which rooms the home server was a member of and room alias mappings.

Before running the command the homeserver should be first completely shutdown. To run it, simply specify the location of the database, e.g.:

> ./scripts/database-prepare-for-0.0.1.sh "homeserver.db"

Once this has successfully completed it will be safe to restart the homeserver. You may notice that the homeserver takes a few seconds longer to restart than usual as it reinitializes the database.

On startup of the new version, users can either rejoin remote rooms using room aliases or by being reinvited. Alternatively, if any other homeserver sends a message to a room that the homeserver was previously in the local HS will automatically rejoin the room.

# MSC1711 Certificates FAQ

## Historical Note

This document was originally written to guide server admins through the upgrade path towards Synapse 1.0. Specifically, MSC1711 required that all servers present valid TLS certificates on their federation API. Admins were encouraged to achieve compliance from version 0.99.0 (released in February 2019) ahead of version 1.0 (released June 2019) enforcing the certificate checks.

Much of what follows is now outdated since most admins will have already upgraded, however it may be of use to those with old installs returning to the project.

If you are setting up a server from scratch you almost certainly should look at the installation guide instead.

## Introduction

The goal of Synapse 0.99.0 is to act as a stepping stone to Synapse 1.0.0. It supports the r0.1 release of the server to server specification, but is compatible with both the legacy Matrix federation behaviour (pre-r0.1) as well as post-r0.1 behaviour, in order to allow for a smooth upgrade across the federation.

The most important thing to know is that Synapse 1.0.0 will require a valid TLS certificate on federation endpoints. Self signed certificates will not be sufficient.

Synapse 0.99.0 makes it easy to configure TLS certificates and will interoperate with both >= 1.0.0 servers as well as existing servers yet to upgrade.

It is critical that all admins upgrade to 0.99.0 and configure a valid TLS certificate. Admins will have 1 month to do so, after which 1.0.0 will be released and those servers without a valid certificate will not longer be able to federate with >= 1.0.0 servers.

Full details on how to carry out this configuration change is given below. A timeline and some frequently asked questions are also given below.

For more details and context on the release of the r0.1 Server/Server API and imminent Matrix 1.0 release, you can also see our main talk from FOSDEM 2019.

## Contents

- Timeline
- Configuring certificates for compatibility with Synapse 1.0
- FAQ
  - Synapse 0.99.0 has just been released, what do I need to do right now?
  - How do I upgrade?
  - What will happen if I do not set up a valid federation certificate immediately?
  - What will happen if I do nothing at all?
  - When do I need a SRV record or .well-known URI?
  - Can I still use an SRV record?
  - I have created a .well-known URI. Do I still need an SRV record?
  - It used to work just fine, why are you breaking everything?
  - Can I manage my own certificates rather than having Synapse renew certificates itself?
  - Do you still recommend against using a reverse proxy on the federation port?
  - Do I still need to give my TLS certificates to Synapse if I am using a reverse proxy?
  - Do I need the same certificate for the client and federation port?
  - How do I tell Synapse to reload my keys/certificates after I replace them?

## Timeline

5th Feb 2019 - Synapse 0.99.0 is released.

All server admins are encouraged to upgrade.

0.99.0:

- provides support for ACME to make setting up Let's Encrypt certs easy, as well as .well-known support.

- does not enforce that a valid CA cert is present on the federation API, but rather makes it easy to set one up.

- provides support for .well-known

Admins should upgrade and configure a valid CA cert. Homeservers that require a .well-known entry (see below), should retain their SRV record and use it alongside their .well-known record.

10th June 2019 - Synapse 1.0.0 is released

1.0.0 is scheduled for release on 10th June. In accordance with the the S2S spec 1.0.0 will enforce certificate validity. This means that any homeserver without a valid certificate after this point will no longer be able to federate with 1.0.0 servers.

## Configuring certificates for compatibility with Synapse 1.0.0

### If you do not currently have an SRV record

In this case, your `server_name` points to the host where your Synapse is running. There is no need to create a `.well-known` URI or an SRV record, but you will need to give Synapse a valid, signed, certificate.

### If you do have an SRV record currently

If you are using an SRV record, your matrix domain (`server_name`) may not point to the same host that your Synapse is running on (the 'target domain'). (If it does, you can follow the recommendation above; otherwise, read on.)

Let's assume that your `server_name` is `example.com`, and your Synapse is hosted at a target domain of `customer.example.net`. Currently you should have an SRV record which looks like:

    _matrix._tcp.example.com. IN SRV 10 5 8000 customer.example.net.

In this situation, you have three choices for how to proceed:

#### Option 1: give Synapse a certificate for your matrix domain

Synapse 1.0 will expect your server to present a TLS certificate for your `server_name` (`example.com` in the above example). You can achieve this by acquiring a certificate for the `server_name` yourself (for example, using `certbot`), and giving it and the key to Synapse via `tls_certificate_path` and `tls_private_key_path`.

#### Option 2: run Synapse behind a reverse proxy

If you have an existing reverse proxy set up with correct TLS certificates for your domain, you can simply route all traffic through the reverse proxy by updating the SRV record appropriately (or removing it, if the proxy listens on 8448).

See the reverse proxy documentation for information on setting up a reverse proxy.

#### Option 3: add a .well-known file to delegate your matrix traffic

This will allow you to keep Synapse on a separate domain, without having to give it a certificate for the matrix domain.

You can do this with a `.well-known` file as follows:

1. Keep the SRV record in place - it is needed for backwards compatibility with Synapse 0.34 and earlier.

2. Give Synapse a certificate corresponding to the target domain (`customer.example.net` in the above example). You can do this by acquire a certificate for the target domain and giving it to Synapse via `tls_certificate_path` and `tls_private_key_path`.

3. Restart Synapse to ensure the new certificate is loaded.

4. Arrange for a `.well-known` file at `https://<server_name>/.well-known/matrix/server` with contents:

       {"m.server": "<target server name>"}

   where the target server name is resolved as usual (i.e. SRV lookup, falling back to talking to port 8448).

   In the above example, where synapse is listening on port 8000, `https://example.com/.well-known/matrix/server` should have `m.server` set to one of:

   1. `customer.example.net` ─ with a SRV record on `_matrix._tcp.customer.example.com` pointing to port 8000, or:

   2. `customer.example.net` ─ updating synapse to listen on the default port 8448, or:

   3. `customer.example.net:8000` ─ ensuring that if there is a reverse proxy on `customer.example.net:8000` it correctly handles HTTP requests with Host header set to `customer.example.net:8000`.

## FAQ

### Synapse 0.99.0 has just been released, what do I need to do right now?

Upgrade as soon as you can in preparation for Synapse 1.0.0, and update your TLS certificates as above.

### What will happen if I do not set up a valid federation certificate immediately?

Nothing initially, but once 1.0.0 is in the wild it will not be possible to federate with 1.0.0 servers.

### What will happen if I do nothing at all?

If the admin takes no action at all, and remains on a Synapse < 0.99.0 then the homeserver will be unable to federate with those who have implemented .well-known. Then, as above, once the month upgrade window has expired the homeserver will not be able to federate with any Synapse >= 1.0.0

### When do I need a SRV record or .well-known URI?

If your homeserver listens on the default federation port (8448), and your `server_name` points to the host that your homeserver runs on, you do not need an SRV record or `.well-known/matrix/server` URI.

For instance, if you registered `example.com` and pointed its DNS A record at a fresh Upcloud VPS or similar, you could install Synapse 0.99 on that host, giving it a server_name of `example.com`, and it would automatically generate a valid TLS certificate for you via Let's Encrypt and no SRV record or `.well-known` URI would be needed.

This is the common case, although you can add an SRV record or `.well-known/matrix/server` URI for completeness if you wish.

However, if your server does not listen on port 8448, or if your `server_name` does not point to the host that your homeserver runs on, you will need to let other servers know how to find it.

In this case, you should see "If you do have an SRV record currently" above.

### Can I still use an SRV record?

Firstly, if you didn't need an SRV record before (because your server is listening on port 8448 of your server_name), you certainly don't need one now: the defaults are still the same.

If you previously had an SRV record, you can keep using it provided you are able to give Synapse a TLS certificate corresponding to your server name. For example, suppose you had the following SRV record, which directs matrix traffic for example.com to matrix.example.com:443:

    _matrix._tcp.example.com. IN SRV 10 5 443 matrix.example.com

In this case, Synapse must be given a certificate for example.com - or be configured to acquire one from Let's Encrypt.

If you are unable to give Synapse a certificate for your server_name, you will also need to use a .well-known URI instead. However, see also "I have created a .well-known URI. Do I still need an SRV record?".

### I have created a .well-known URI. Do I still need an SRV record?

As of Synapse 0.99, Synapse will first check for the existence of a `.well-known` URI and follow any delegation it suggests. It will only then check for the existence of an SRV record.

That means that the SRV record will often be redundant. However, you should remember that there may still be older versions of Synapse in the federation which do not understand `.well-known` URIs, so if you removed your SRV record you would no longer be able to federate with them.

It is therefore best to leave the SRV record in place for now. Synapse 0.34 and earlier will follow the SRV record (and not care about the invalid certificate). Synapse 0.99 and later will follow the .well-known URI, with the correct certificate chain.

### It used to work just fine, why are you breaking everything?

We have always wanted Matrix servers to be as easy to set up as possible, and so back when we started federation in 2014 we didn't want admins to have to go through the cumbersome process of buying a valid TLS certificate to run a server. This was before Let's Encrypt came along and made getting a free and valid TLS certificate straightforward. So instead, we adopted a system based on Perspectives: an approach where you check a set of "notary servers" (in practice, homeservers) to vouch for the validity of a certificate rather than having it signed by a CA. As long as enough different notaries agree on the certificate's validity, then it is trusted.

However, in practice this has never worked properly. Most people only use the default notary server (matrix.org), leading to inadvertent centralisation which we want to eliminate. Meanwhile, we never implemented the full consensus algorithm to query the servers participating in a room to determine consensus on whether a given certificate is valid. This is fiddly to get right (especially in face of sybil attacks), and we found ourselves questioning whether it was worth the effort to finish the work and commit to maintaining a secure certificate validation system as opposed to focusing on core Matrix development.

Meanwhile, Let's Encrypt came along in 2016, and put the final nail in the coffin of the Perspectives project (which was already pretty dead). So, the Spec Core Team decided that a better approach would be to mandate valid TLS certificates for federation alongside the rest of the Web. More details can be found in MSC1711.

This results in a breaking change, which is disruptive, but absolutely critical for the security model. However, the existence of Let's Encrypt as a trivial way to replace the old self-signed certificates with valid CA-signed ones helps smooth things over massively, especially as Synapse can now automate Let's Encrypt certificate generation if needed.

### Can I manage my own certificates rather than having Synapse renew certificates itself?

Yes, you are welcome to manage your certificates yourself. Synapse will only attempt to obtain certificates from Let's Encrypt if you configure it to do so.The only requirement is that there is a valid TLS cert present for federation end points.

### Do you still recommend against using a reverse proxy on the federation port?

We no longer actively recommend against using a reverse proxy. Many admins will find it easier to direct federation traffic to a reverse proxy and manage their own TLS certificates, and this is a supported configuration.

See the reverse proxy documentation for information on setting up a reverse proxy.

### Do I still need to give my TLS certificates to Synapse if I am using a reverse proxy?

Practically speaking, this is no longer necessary.

If you are using a reverse proxy for all of your TLS traffic, then you can set `no_tls: True`. In that case, the only reason Synapse needs the certificate is to populate a legacy 'tls_fingerprints' field in the federation API. This is ignored by Synapse 0.99.0 and later, and the only time pre-0.99 Synapses will check it is when attempting to fetch the server keys - and generally this is delegated via `matrix.org`, which is on 0.99.0.

However, there is a bug in Synapse 0.99.0 4554 which prevents Synapse from starting if you do not give it a TLS certificate. To work around this, you can give it any TLS certificate at all. This will be fixed soon.

### Do I need the same certificate for the client and federation port?

No. There is nothing stopping you from using different certificates, particularly if you are using a reverse proxy. However, Synapse will use the same certificate on any ports where TLS is configured.

### How do I tell Synapse to reload my keys/certificates after I replace them?

Synapse will reload the keys and certificates when it receives a SIGHUP - for example `kill -HUP $(cat homeserver.pid)`. Alternatively, simply restart Synapse, though this will result in downtime while it restarts.

# Setting up federation

Federation is the process by which users on different servers can participate in the same room. For this to work, those other servers must be able to contact yours to send messages.

The `server_name` configured in the Synapse configuration file (often `homeserver.yaml`) defines how resources (users, rooms, etc.) will be identified (eg: `@user:example.com`, `#room:example.com`). By default, it is also the domain that other servers will use to try to reach your server (via port 8448). This is easy to set up and will work provided you set the `server_name` to match your machine's public DNS hostname.

For this default configuration to work, you will need to listen for TLS connections on port 8448. The preferred way to do that is by using a reverse proxy: see the reverse proxy documentation for instructions on how to correctly set one up.

In some cases you might not want to run Synapse on the machine that has the `server_name` as its public DNS hostname, or you might want federation traffic to use a different port than 8448. For example, you might want to have your user names look like `@user:example.com`, but you want to run Synapse on `synapse.example.com` on port 443. This can be done using delegation, which allows an admin to control where federation traffic should be sent. See the delegation documentation for instructions on how to set this up.

Once federation has been configured, you should be able to join a room over federation. A good place to start is `#synapse:matrix.org` - a room for Synapse admins.

## Troubleshooting

You can use the federation tester to check if your homeserver is configured correctly. Alternatively try the JSON API used by the federation tester. Note that you'll have to modify this URL to replace `DOMAIN` with your `server_name`. Hitting the API directly provides extra detail.

The typical failure mode for federation is that when the server tries to join a room, it is rejected with "401: Unauthorized". Generally this means that other servers in the room could not access yours. (Joining a room over federation is a complicated dance which requires connections in both directions).

Another common problem is that people on other servers can't join rooms that you invite them to. This can be caused by an incorrectly-configured reverse proxy: see the reverse proxy documentation for instructions on how to correctly configure a reverse proxy.

### Known issues

HTTP `308 Permanent Redirect` redirects are not followed: Due to missing features in the HTTP library used by Synapse, 308 redirects are currently not followed by federating servers, which can cause `M_UNKNOWN` or `401 Unauthorized` errors. This may affect users who are redirecting apex-to-www (e.g. `example.com` -> `www.example.com`), and especially users of the Kubernetes Nginx Ingress module, which uses 308 redirect codes by default. For those Kubernetes users, this Stackoverflow post might be helpful. For other users, switching to a `301 Moved Permanently` code may be an option. 308 redirect codes will be supported properly in a future release of Synapse.

## Running a demo federation of Synapses

If you want to get up and running quickly with a trio of homeservers in a private federation, there is a script in the `demo` directory. This is mainly useful just for development purposes. See demo/README.

# Configuration

This section contains information on tweaking Synapse via the various options in the configuration file. A configuration file should have been generated when you installed Synapse.

# Homeserver Sample Configuration File

Below is a sample homeserver configuration file. The homeserver configuration file can be tweaked to change the behaviour of your homeserver. A restart of the server is generally required to apply any changes made to this file.

Note that the contents below are not intended to be copied and used as the basis for a real homeserver.yaml. Instead, if you are starting from scratch, please generate a fresh config using Synapse by following the instructions in Installation.

    # This file is maintained as an up-to-date snapshot of the default
    # homeserver.yaml configuration generated by Synapse.
    #
    # It is intended to act as a reference for the default configuration,
    # helping admins keep track of new options and other changes, and compare
    # their configs with the current default.  As such, many of the actual
    # config values shown are placeholders.
    #
    # It is *not* intended to be copied and used as the basis for a real
    # homeserver.yaml. Instead, if you are starting from scratch, please generate
    # a fresh config using Synapse by following the instructions in
    # https://matrix-org.github.io/synapse/latest/setup/installation.html.

    # Configuration options that take a time period can be set using a number
    # followed by a letter. Letters have the following meanings:
    # s = second
    # m = minute
    # h = hour
    # d = day
    # w = week
    # y = year
    # For example, setting redaction_retention_period: 5m would remove redacted
    # messages from the database after 5 minutes, rather than 5 months.

    ################################################################################

    # Configuration file for Synapse.
    #
    # This is a YAML file: see [1] for a quick introduction. Note in particular
    # that *indentation is important*: all the elements of a list or dictionary
    # should have the same indentation.
    #
    # [1] https://docs.ansible.com/ansible/latest/reference_appendices/YAMLSyntax.html

    ## Modules ##

    # Server admins can expand Synapse's functionality with external modules.
    #
    # See https://matrix-org.github.io/synapse/latest/modules.html for more
    # documentation on how to configure or create custom modules for Synapse.
    #
    modules:
        # - module: my_super_module.MySuperClass
        #   config:
        #       do_thing: true
        # - module: my_other_super_module.SomeClass
        #   config: {}

    ## Server ##

    # The public-facing domain of the server
    #
    # The server_name name will appear at the end of usernames and room addresses
    # created on this server. For example if the server_name was example.com,
    # usernames on this server would be in the format @user:example.com
    #
    # In most cases you should avoid using a matrix specific subdomain such as
    # matrix.example.com or synapse.example.com as the server_name for the same
    # reasons you wouldn't use user@email.example.com as your email address.
    # See https://matrix-org.github.io/synapse/latest/delegate.html
    # for information on how to host Synapse on a subdomain while preserving
    # a clean server_name.
    #
    # The server_name cannot be changed later so it is important to
    # configure this correctly before you start Synapse. It should be all
    # lowercase and may contain an explicit port.
    # Examples: matrix.org, localhost:8080
    #
    server_name: "SERVERNAME"

    # When running as a daemon, the file to store the pid in
    #
    pid_file: DATADIR/homeserver.pid

    # The absolute URL to the web client which /_matrix/client will redirect
    # to if 'webclient' is configured under the 'listeners' configuration.
    #
    # This option can be also set to the filesystem path to the web client
    # which will be served at /_matrix/client/ if 'webclient' is configured
    # under the 'listeners' configuration, however this is a security risk:
    # https://github.com/matrix-org/synapse#security-note
    #
    #web_client_location: https://riot.example.com/

    # The public-facing base URL that clients use to access this Homeserver (not
    # including _matrix/...). This is the same URL a user might enter into the
    # 'Custom Homeserver URL' field on their client. If you use Synapse with a
    # reverse proxy, this should be the URL to reach Synapse via the proxy.
    # Otherwise, it should be the URL to reach Synapse's client HTTP listener (see
    # 'listeners' below).
    #
    #public_baseurl: https://example.com/

    # Set the soft limit on the number of file descriptors synapse can use
    # Zero is used to indicate synapse should set the soft limit to the
    # hard limit.
    #
    #soft_file_limit: 0

    # Presence tracking allows users to see the state (e.g online/offline)
    # of other local and remote users.
    #
    presence:
      # Uncomment to disable presence tracking on this homeserver. This option
      # replaces the previous top-level 'use_presence' option.
      #
      #enabled: false

    # Whether to require authentication to retrieve profile data (avatars,
    # display names) of other users through the client API. Defaults to
    # 'false'. Note that profile data is also available via the federation
    # API, unless allow_profile_lookup_over_federation is set to false.
    #
    #require_auth_for_profile_requests: true

    # Uncomment to require a user to share a room with another user in order
    # to retrieve their profile information. Only checked on Client-Server
    # requests. Profile requests from other servers should be checked by the
    # requesting server. Defaults to 'false'.
    #
    #limit_profile_requests_to_users_who_share_rooms: true

    # Uncomment to prevent a user's profile data from being retrieved and
    # displayed in a room until they have joined it. By default, a user's
    # profile data is included in an invite event, regardless of the values
    # of the above two settings, and whether or not the users share a server.
    # Defaults to 'true'.
    #
    #include_profile_data_on_invite: false

    # If set to 'true', removes the need for authentication to access the server's
    # public rooms directory through the client API, meaning that anyone can
    # query the room directory. Defaults to 'false'.
    #
    #allow_public_rooms_without_auth: true

    # If set to 'true', allows any other homeserver to fetch the server's public
    # rooms directory via federation. Defaults to 'false'.
    #
    #allow_public_rooms_over_federation: true

    # The default room version for newly created rooms.
    #
    # Known room versions are listed here:
    # https://matrix.org/docs/spec/#complete-list-of-room-versions
    #
    # For example, for room version 1, default_room_version should be set
    # to "1".
    #
    #default_room_version: "6"

    # The GC threshold parameters to pass to `gc.set_threshold`, if defined
    #
    #gc_thresholds: [700, 10, 10]

    # The minimum time in seconds between each GC for a generation, regardless of
    # the GC thresholds. This ensures that we don't do GC too frequently.
    #
    # A value of `[1s, 10s, 30s]` indicates that a second must pass between consecutive
    # generation 0 GCs, etc.
    #
    # Defaults to `[1s, 10s, 30s]`.
    #
    #gc_min_interval: [0.5s, 30s, 1m]

    # Set the limit on the returned events in the timeline in the get
    # and sync operations. The default value is 100. -1 means no upper limit.
    #
    # Uncomment the following to increase the limit to 5000.
    #
    #filter_timeline_limit: 5000

    # Whether room invites to users on this server should be blocked
    # (except those sent by local server admins). The default is False.
    #
    #block_non_admin_invites: true

    # Room searching
    #
    # If disabled, new messages will not be indexed for searching and users
    # will receive errors when searching for messages. Defaults to enabled.
    #
    #enable_search: false

    # Prevent outgoing requests from being sent to the following blacklisted IP address
    # CIDR ranges. If this option is not specified then it defaults to private IP
    # address ranges (see the example below).
    #
    # The blacklist applies to the outbound requests for federation, identity servers,
    # push servers, and for checking key validity for third-party invite events.
    #
    # (0.0.0.0 and :: are always blacklisted, whether or not they are explicitly
    # listed here, since they correspond to unroutable addresses.)
    #
    # This option replaces federation_ip_range_blacklist in Synapse v1.25.0.
    #
    # Note: The value is ignored when an HTTP proxy is in use
    #
    #ip_range_blacklist:
    #  - '127.0.0.0/8'
    #  - '10.0.0.0/8'
    #  - '172.16.0.0/12'
    #  - '192.168.0.0/16'
    #  - '100.64.0.0/10'
    #  - '192.0.0.0/24'
    #  - '169.254.0.0/16'
    #  - '192.88.99.0/24'
    #  - '198.18.0.0/15'
    #  - '192.0.2.0/24'
    #  - '198.51.100.0/24'
    #  - '203.0.113.0/24'
    #  - '224.0.0.0/4'
    #  - '::1/128'
    #  - 'fe80::/10'
    #  - 'fc00::/7'
    #  - '2001:db8::/32'
    #  - 'ff00::/8'
    #  - 'fec0::/10'

    # List of IP address CIDR ranges that should be allowed for federation,
    # identity servers, push servers, and for checking key validity for
    # third-party invite events. This is useful for specifying exceptions to
    # wide-ranging blacklisted target IP ranges - e.g. for communication with
    # a push server only visible in your network.
    #
    # This whitelist overrides ip_range_blacklist and defaults to an empty
    # list.
    #
    #ip_range_whitelist:
    #   - '192.168.1.1'

    # List of ports that Synapse should listen on, their purpose and their
    # configuration.
    #
    # Options for each listener include:
    #
    #   port: the TCP port to bind to
    #
    #   bind_addresses: a list of local addresses to listen on. The default is
    #       'all local interfaces'.
    #
    #   type: the type of listener. Normally 'http', but other valid options are:
    #       'manhole' (see https://matrix-org.github.io/synapse/latest/manhole.html),
    #       'metrics' (see https://matrix-org.github.io/synapse/latest/metrics-howto.html),
    #       'replication' (see https://matrix-org.github.io/synapse/latest/workers.html).
    #
    #   tls: set to true to enable TLS for this listener. Will use the TLS
    #       key/cert specified in tls_private_key_path / tls_certificate_path.
    #
    #   x_forwarded: Only valid for an 'http' listener. Set to true to use the
    #       X-Forwarded-For header as the client IP. Useful when Synapse is
    #       behind a reverse-proxy.
    #
    #   resources: Only valid for an 'http' listener. A list of resources to host
    #       on this port. Options for each resource are:
    #
    #       names: a list of names of HTTP resources. See below for a list of
    #           valid resource names.
    #
    #       compress: set to true to enable HTTP compression for this resource.
    #
    #   additional_resources: Only valid for an 'http' listener. A map of
    #        additional endpoints which should be loaded via dynamic modules.
    #
    # Valid resource names are:
    #
    #   client: the client-server API (/_matrix/client), and the synapse admin
    #       API (/_synapse/admin). Also implies 'media' and 'static'.
    #
    #   consent: user consent forms (/_matrix/consent).
    #       See https://matrix-org.github.io/synapse/latest/consent_tracking.html.
    #
    #   federation: the server-server API (/_matrix/federation). Also implies
    #       'media', 'keys', 'openid'
    #
    #   keys: the key discovery API (/_matrix/keys).
    #
    #   media: the media API (/_matrix/media).
    #
    #   metrics: the metrics interface.
    #       See https://matrix-org.github.io/synapse/latest/metrics-howto.html.
    #
    #   openid: OpenID authentication.
    #
    #   replication: the HTTP replication API (/_synapse/replication).
    #       See https://matrix-org.github.io/synapse/latest/workers.html.
    #
    #   static: static resources under synapse/static (/_matrix/static). (Mostly
    #       useful for 'fallback authentication'.)
    #
    #   webclient: A web client. Requires web_client_location to be set.
    #
    listeners:
      # TLS-enabled listener: for when matrix traffic is sent directly to synapse.
      #
      # Disabled by default. To enable it, uncomment the following. (Note that you
      # will also need to give Synapse a TLS key and certificate: see the TLS section
      # below.)
      #
      #- port: 8448
      #  type: http
      #  tls: true
      #  resources:
      #    - names: [client, federation]

      # Unsecure HTTP listener: for when matrix traffic passes through a reverse proxy
      # that unwraps TLS.
      #
      # If you plan to use a reverse proxy, please see
      # https://matrix-org.github.io/synapse/latest/reverse_proxy.html.
      #
      - port: 8008
        tls: false
        type: http
        x_forwarded: true
        bind_addresses: ['::1', '127.0.0.1']

        resources:
          - names: [client, federation]
            compress: false

        # example additional_resources:
        #
        #additional_resources:
        #  "/_matrix/my/custom/endpoint":
        #    module: my_module.CustomRequestHandler
        #    config: {}

      # Turn on the twisted ssh manhole service on localhost on the given
      # port.
      #
      #- port: 9000
      #  bind_addresses: ['::1', '127.0.0.1']
      #  type: manhole

    # Connection settings for the manhole
    #
    manhole_settings:
      # The username for the manhole. This defaults to 'matrix'.
      #
      #username: manhole

      # The password for the manhole. This defaults to 'rabbithole'.
      #
      #password: mypassword

      # The private and public SSH key pair used to encrypt the manhole traffic.
      # If these are left unset, then hardcoded and non-secret keys are used,
      # which could allow traffic to be intercepted if sent over a public network.
      #
      #ssh_priv_key_path: CONFDIR/id_rsa
      #ssh_pub_key_path: CONFDIR/id_rsa.pub

    # Forward extremities can build up in a room due to networking delays between
    # homeservers. Once this happens in a large room, calculation of the state of
    # that room can become quite expensive. To mitigate this, once the number of
    # forward extremities reaches a given threshold, Synapse will send an
    # org.matrix.dummy_event event, which will reduce the forward extremities
    # in the room.
    #
    # This setting defines the threshold (i.e. number of forward extremities in the
    # room) at which dummy events are sent. The default value is 10.
    #
    #dummy_events_threshold: 5

    ## Homeserver blocking ##

    # How to reach the server admin, used in ResourceLimitError
    #
    #admin_contact: 'mailto:admin@server.com'

    # Global blocking
    #
    #hs_disabled: false
    #hs_disabled_message: 'Human readable reason for why the HS is blocked'

    # Monthly Active User Blocking
    #
    # Used in cases where the admin or server owner wants to limit to the
    # number of monthly active users.
    #
    # 'limit_usage_by_mau' disables/enables monthly active user blocking. When
    # enabled and a limit is reached the server returns a 'ResourceLimitError'
    # with error type Codes.RESOURCE_LIMIT_EXCEEDED
    #
    # 'max_mau_value' is the hard limit of monthly active users above which
    # the server will start blocking user actions.
    #
    # 'mau_trial_days' is a means to add a grace period for active users. It
    # means that users must be active for this number of days before they
    # can be considered active and guards against the case where lots of users
    # sign up in a short space of time never to return after their initial
    # session.
    #
    # 'mau_limit_alerting' is a means of limiting client side alerting
    # should the mau limit be reached. This is useful for small instances
    # where the admin has 5 mau seats (say) for 5 specific people and no
    # interest increasing the mau limit further. Defaults to True, which
    # means that alerting is enabled
    #
    #limit_usage_by_mau: false
    #max_mau_value: 50
    #mau_trial_days: 2
    #mau_limit_alerting: false

    # If enabled, the metrics for the number of monthly active users will
    # be populated, however no one will be limited. If limit_usage_by_mau
    # is true, this is implied to be true.
    #
    #mau_stats_only: false

    # Sometimes the server admin will want to ensure certain accounts are
    # never blocked by mau checking. These accounts are specified here.
    #
    #mau_limit_reserved_threepids:
    #  - medium: 'email'
    #    address: 'reserved_user@example.com'

    # Used by phonehome stats to group together related servers.
    #server_context: context

    # Resource-constrained homeserver settings
    #
    # When this is enabled, the room "complexity" will be checked before a user
    # joins a new remote room. If it is above the complexity limit, the server will
    # disallow joining, or will instantly leave.
    #
    # Room complexity is an arbitrary measure based on factors such as the number of
    # users in the room.
    #
    limit_remote_rooms:
      # Uncomment to enable room complexity checking.
      #
      #enabled: true

      # the limit above which rooms cannot be joined. The default is 1.0.
      #
      #complexity: 0.5

      # override the error which is returned when the room is too complex.
      #
      #complexity_error: "This room is too complex."

      # allow server admins to join complex rooms. Default is false.
      #
      #admins_can_join: true

    # Whether to require a user to be in the room to add an alias to it.
    # Defaults to 'true'.
    #
    #require_membership_for_aliases: false

    # Whether to allow per-room membership profiles through the send of membership
    # events with profile information that differ from the target's global profile.
    # Defaults to 'true'.
    #
    #allow_per_room_profiles: false

    # How long to keep redacted events in unredacted form in the database. After
    # this period redacted events get replaced with their redacted form in the DB.
    #
    # Defaults to `7d`. Set to `null` to disable.
    #
    #redaction_retention_period: 28d

    # How long to track users' last seen time and IPs in the database.
    #
    # Defaults to `28d`. Set to `null` to disable clearing out of old rows.
    #
    #user_ips_max_age: 14d

    # Inhibits the /requestToken endpoints from returning an error that might leak
    # information about whether an e-mail address is in use or not on this
    # homeserver.
    # Note that for some endpoints the error situation is the e-mail already being
    # used, and for others the error is entering the e-mail being unused.
    # If this option is enabled, instead of returning an error, these endpoints will
    # act as if no error happened and return a fake session ID ('sid') to clients.
    #
    #request_token_inhibit_3pid_errors: true

    # A list of domains that the domain portion of 'next_link' parameters
    # must match.
    #
    # This parameter is optionally provided by clients while requesting
    # validation of an email or phone number, and maps to a link that
    # users will be automatically redirected to after validation
    # succeeds. Clients can make use this parameter to aid the validation
    # process.
    #
    # The whitelist is applied whether the homeserver or an
    # identity server is handling validation.
    #
    # The default value is no whitelist functionality; all domains are
    # allowed. Setting this value to an empty list will instead disallow
    # all domains.
    #
    #next_link_domain_whitelist: ["matrix.org"]

    # Templates to use when generating email or HTML page contents.
    #
    templates:
      # Directory in which Synapse will try to find template files to use to generate
      # email or HTML page contents.
      # If not set, or a file is not found within the template directory, a default
      # template from within the Synapse package will be used.
      #
      # See https://matrix-org.github.io/synapse/latest/templates.html for more
      # information about using custom templates.
      #
      #custom_template_directory: /path/to/custom/templates/

    # Message retention policy at the server level.
    #
    # Room admins and mods can define a retention period for their rooms using the
    # 'm.room.retention' state event, and server admins can cap this period by setting
    # the 'allowed_lifetime_min' and 'allowed_lifetime_max' config options.
    #
    # If this feature is enabled, Synapse will regularly look for and purge events
    # which are older than the room's maximum retention period. Synapse will also
    # filter events received over federation so that events that should have been
    # purged are ignored and not stored again.
    #
    retention:
      # The message retention policies feature is disabled by default. Uncomment the
      # following line to enable it.
      #
      #enabled: true

      # Default retention policy. If set, Synapse will apply it to rooms that lack the
      # 'm.room.retention' state event. Currently, the value of 'min_lifetime' doesn't
      # matter much because Synapse doesn't take it into account yet.
      #
      #default_policy:
      #  min_lifetime: 1d
      #  max_lifetime: 1y

      # Retention policy limits. If set, and the state of a room contains a
      # 'm.room.retention' event in its state which contains a 'min_lifetime' or a
      # 'max_lifetime' that's out of these bounds, Synapse will cap the room's policy
      # to these limits when running purge jobs.
      #
      #allowed_lifetime_min: 1d
      #allowed_lifetime_max: 1y

      # Server admins can define the settings of the background jobs purging the
      # events which lifetime has expired under the 'purge_jobs' section.
      #
      # If no configuration is provided, a single job will be set up to delete expired
      # events in every room daily.
      #
      # Each job's configuration defines which range of message lifetimes the job
      # takes care of. For example, if 'shortest_max_lifetime' is '2d' and
      # 'longest_max_lifetime' is '3d', the job will handle purging expired events in
      # rooms whose state defines a 'max_lifetime' that's both higher than 2 days, and
      # lower than or equal to 3 days. Both the minimum and the maximum value of a
      # range are optional, e.g. a job with no 'shortest_max_lifetime' and a
      # 'longest_max_lifetime' of '3d' will handle every room with a retention policy
      # which 'max_lifetime' is lower than or equal to three days.
      #
      # The rationale for this per-job configuration is that some rooms might have a
      # retention policy with a low 'max_lifetime', where history needs to be purged
      # of outdated messages on a more frequent basis than for the rest of the rooms
      # (e.g. every 12h), but not want that purge to be performed by a job that's
      # iterating over every room it knows, which could be heavy on the server.
      #
      # If any purge job is configured, it is strongly recommended to have at least
      # a single job with neither 'shortest_max_lifetime' nor 'longest_max_lifetime'
      # set, or one job without 'shortest_max_lifetime' and one job without
      # 'longest_max_lifetime' set. Otherwise some rooms might be ignored, even if
      # 'allowed_lifetime_min' and 'allowed_lifetime_max' are set, because capping a
      # room's policy to these values is done after the policies are retrieved from
      # Synapse's database (which is done using the range specified in a purge job's
      # configuration).
      #
      #purge_jobs:
      #  - longest_max_lifetime: 3d
      #    interval: 12h
      #  - shortest_max_lifetime: 3d
      #    interval: 1d

    ## TLS ##

    # PEM-encoded X509 certificate for TLS.
    # This certificate, as of Synapse 1.0, will need to be a valid and verifiable
    # certificate, signed by a recognised Certificate Authority.
    #
    # Be sure to use a `.pem` file that includes the full certificate chain including
    # any intermediate certificates (for instance, if using certbot, use
    # `fullchain.pem` as your certificate, not `cert.pem`).
    #
    #tls_certificate_path: "CONFDIR/SERVERNAME.tls.crt"

    # PEM-encoded private key for TLS
    #
    #tls_private_key_path: "CONFDIR/SERVERNAME.tls.key"

    # Whether to verify TLS server certificates for outbound federation requests.
    #
    # Defaults to `true`. To disable certificate verification, uncomment the
    # following line.
    #
    #federation_verify_certificates: false

    # The minimum TLS version that will be used for outbound federation requests.
    #
    # Defaults to `1`. Configurable to `1`, `1.1`, `1.2`, or `1.3`. Note
    # that setting this value higher than `1.2` will prevent federation to most
    # of the public Matrix network: only configure it to `1.3` if you have an
    # entirely private federation setup and you can ensure TLS 1.3 support.
    #
    #federation_client_minimum_tls_version: 1.2

    # Skip federation certificate verification on the following whitelist
    # of domains.
    #
    # This setting should only be used in very specific cases, such as
    # federation over Tor hidden services and similar. For private networks
    # of homeservers, you likely want to use a private CA instead.
    #
    # Only effective if federation_verify_certicates is `true`.
    #
    #federation_certificate_verification_whitelist:
    #  - lon.example.com
    #  - *.domain.com
    #  - *.onion

    # List of custom certificate authorities for federation traffic.
    #
    # This setting should only normally be used within a private network of
    # homeservers.
    #
    # Note that this list will replace those that are provided by your
    # operating environment. Certificates must be in PEM format.
    #
    #federation_custom_ca_list:
    #  - myCA1.pem
    #  - myCA2.pem
    #  - myCA3.pem

    ## Federation ##

    # Restrict federation to the following whitelist of domains.
    # N.B. we recommend also firewalling your federation listener to limit
    # inbound federation traffic as early as possible, rather than relying
    # purely on this application-layer restriction.  If not specified, the
    # default is to whitelist everything.
    #
    #federation_domain_whitelist:
    #  - lon.example.com
    #  - nyc.example.com
    #  - syd.example.com

    # Report prometheus metrics on the age of PDUs being sent to and received from
    # the following domains. This can be used to give an idea of "delay" on inbound
    # and outbound federation, though be aware that any delay can be due to problems
    # at either end or with the intermediate network.
    #
    # By default, no domains are monitored in this way.
    #
    #federation_metrics_domains:
    #  - matrix.org
    #  - example.com

    # Uncomment to disable profile lookup over federation. By default, the
    # Federation API allows other homeservers to obtain profile data of any user
    # on this homeserver. Defaults to 'true'.
    #
    #allow_profile_lookup_over_federation: false

    # Uncomment to disable device display name lookup over federation. By default, the
    # Federation API allows other homeservers to obtain device display names of any user
    # on this homeserver. Defaults to 'true'.
    #
    #allow_device_name_lookup_over_federation: false

    ## Caching ##

    # Caching can be configured through the following options.
    #
    # A cache 'factor' is a multiplier that can be applied to each of
    # Synapse's caches in order to increase or decrease the maximum
    # number of entries that can be stored.

    # The number of events to cache in memory. Not affected by
    # caches.global_factor.
    #
    #event_cache_size: 10K

    caches:
      # Controls the global cache factor, which is the default cache factor
      # for all caches if a specific factor for that cache is not otherwise
      # set.
      #
      # This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
      # variable. Setting by environment variable takes priority over
      # setting through the config file.
      #
      # Defaults to 0.5, which will half the size of all caches.
      #
      #global_factor: 1.0

      # A dictionary of cache name to cache factor for that individual
      # cache. Overrides the global cache factor for a given cache.
      #
      # These can also be set through environment variables comprised
      # of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
      # letters and underscores. Setting by environment variable
      # takes priority over setting through the config file.
      # Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
      #
      # Some caches have '*' and other characters that are not
      # alphanumeric or underscores. These caches can be named with or
      # without the special characters stripped. For example, to specify
      # the cache factor for `*stateGroupCache*` via an environment
      # variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
      #
      per_cache_factors:
        #get_users_who_share_room_with_user: 2.0

      # Controls how long an entry can be in a cache without having been
      # accessed before being evicted. Defaults to None, which means
      # entries are never evicted based on time.
      #
      #expiry_time: 30m

      # Controls how long the results of a /sync request are cached for after
      # a successful response is returned. A higher duration can help clients with
      # intermittent connections, at the cost of higher memory usage.
      #
      # By default, this is zero, which means that sync responses are not cached
      # at all.
      #
      #sync_response_cache_duration: 2m

    ## Database ##

    # The 'database' setting defines the database that synapse uses to store all of
    # its data.
    #
    # 'name' gives the database engine to use: either 'sqlite3' (for SQLite) or
    # 'psycopg2' (for PostgreSQL).
    #
    # 'txn_limit' gives the maximum number of transactions to run per connection
    # before reconnecting. Defaults to 0, which means no limit.
    #
    # 'args' gives options which are passed through to the database engine,
    # except for options starting 'cp_', which are used to configure the Twisted
    # connection pool. For a reference to valid arguments, see:
    #   * for sqlite: https://docs.python.org/3/library/sqlite3.html#sqlite3.connect
    #   * for postgres: https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS
    #   * for the connection pool: https://twistedmatrix.com/documents/current/api/twisted.enterprise.adbapi.ConnectionPool.html#__init__
    #
    #
    # Example SQLite configuration:
    #
    #database:
    #  name: sqlite3
    #  args:
    #    database: /path/to/homeserver.db
    #
    #
    # Example Postgres configuration:
    #
    #database:
    #  name: psycopg2
    #  txn_limit: 10000
    #  args:
    #    user: synapse_user
    #    password: secretpassword
    #    database: synapse
    #    host: localhost
    #    port: 5432
    #    cp_min: 5
    #    cp_max: 10
    #
    # For more information on using Synapse with Postgres,
    # see https://matrix-org.github.io/synapse/latest/postgres.html.
    #
    database:
      name: sqlite3
      args:
        database: DATADIR/homeserver.db

    ## Logging ##

    # A yaml python logging config file as described by
    # https://docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema
    #
    log_config: "CONFDIR/SERVERNAME.log.config"

    ## Ratelimiting ##

    # Ratelimiting settings for client actions (registration, login, messaging).
    #
    # Each ratelimiting configuration is made of two parameters:
    #   - per_second: number of requests a client can send per second.
    #   - burst_count: number of requests a client can send before being throttled.
    #
    # Synapse currently uses the following configurations:
    #   - one for messages that ratelimits sending based on the account the client
    #     is using
    #   - one for registration that ratelimits registration requests based on the
    #     client's IP address.
    #   - one for checking the validity of registration tokens that ratelimits
    #     requests based on the client's IP address.
    #   - one for login that ratelimits login requests based on the client's IP
    #     address.
    #   - one for login that ratelimits login requests based on the account the
    #     client is attempting to log into.
    #   - one for login that ratelimits login requests based on the account the
    #     client is attempting to log into, based on the amount of failed login
    #     attempts for this account.
    #   - one for ratelimiting redactions by room admins. If this is not explicitly
    #     set then it uses the same ratelimiting as per rc_message. This is useful
    #     to allow room admins to deal with abuse quickly.
    #   - two for ratelimiting number of rooms a user can join, "local" for when
    #     users are joining rooms the server is already in (this is cheap) vs
    #     "remote" for when users are trying to join rooms not on the server (which
    #     can be more expensive)
    #   - one for ratelimiting how often a user or IP can attempt to validate a 3PID.
    #   - two for ratelimiting how often invites can be sent in a room or to a
    #     specific user.
    #
    # The defaults are as shown below.
    #
    #rc_message:
    #  per_second: 0.2
    #  burst_count: 10
    #
    #rc_registration:
    #  per_second: 0.17
    #  burst_count: 3
    #
    #rc_registration_token_validity:
    #  per_second: 0.1
    #  burst_count: 5
    #
    #rc_login:
    #  address:
    #    per_second: 0.17
    #    burst_count: 3
    #  account:
    #    per_second: 0.17
    #    burst_count: 3
    #  failed_attempts:
    #    per_second: 0.17
    #    burst_count: 3
    #
    #rc_admin_redaction:
    #  per_second: 1
    #  burst_count: 50
    #
    #rc_joins:
    #  local:
    #    per_second: 0.1
    #    burst_count: 10
    #  remote:
    #    per_second: 0.01
    #    burst_count: 10
    #
    #rc_3pid_validation:
    #  per_second: 0.003
    #  burst_count: 5
    #
    #rc_invites:
    #  per_room:
    #    per_second: 0.3
    #    burst_count: 10
    #  per_user:
    #    per_second: 0.003
    #    burst_count: 5

    # Ratelimiting settings for incoming federation
    #
    # The rc_federation configuration is made up of the following settings:
    #   - window_size: window size in milliseconds
    #   - sleep_limit: number of federation requests from a single server in
    #     a window before the server will delay processing the request.
    #   - sleep_delay: duration in milliseconds to delay processing events
    #     from remote servers by if they go over the sleep limit.
    #   - reject_limit: maximum number of concurrent federation requests
    #     allowed from a single server
    #   - concurrent: number of federation requests to concurrently process
    #     from a single server
    #
    # The defaults are as shown below.
    #
    #rc_federation:
    #  window_size: 1000
    #  sleep_limit: 10
    #  sleep_delay: 500
    #  reject_limit: 50
    #  concurrent: 3

    # Target outgoing federation transaction frequency for sending read-receipts,
    # per-room.
    #
    # If we end up trying to send out more read-receipts, they will get buffered up
    # into fewer transactions.
    #
    #federation_rr_transactions_per_room_per_second: 50

    ## Media Store ##

    # Enable the media store service in the Synapse master. Uncomment the
    # following if you are using a separate media store worker.
    #
    #enable_media_repo: false

    # Directory where uploaded images and attachments are stored.
    #
    media_store_path: "DATADIR/media_store"

    # Media storage providers allow media to be stored in different
    # locations.
    #
    #media_storage_providers:
    #  - module: file_system
    #    # Whether to store newly uploaded local files
    #    store_local: false
    #    # Whether to store newly downloaded remote files
    #    store_remote: false
    #    # Whether to wait for successful storage for local uploads
    #    store_synchronous: false
    #    config:
    #       directory: /mnt/some/other/directory

    # The largest allowed upload size in bytes
    #
    # If you are using a reverse proxy you may also need to set this value in
    # your reverse proxy's config. Notably Nginx has a small max body size by default.
    # See https://matrix-org.github.io/synapse/latest/reverse_proxy.html.
    #
    #max_upload_size: 50M

    # Maximum number of pixels that will be thumbnailed
    #
    #max_image_pixels: 32M

    # Whether to generate new thumbnails on the fly to precisely match
    # the resolution requested by the client. If true then whenever
    # a new resolution is requested by the client the server will
    # generate a new thumbnail. If false the server will pick a thumbnail
    # from a precalculated list.
    #
    #dynamic_thumbnails: false

    # List of thumbnails to precalculate when an image is uploaded.
    #
    #thumbnail_sizes:
    #  - width: 32
    #    height: 32
    #    method: crop
    #  - width: 96
    #    height: 96
    #    method: crop
    #  - width: 320
    #    height: 240
    #    method: scale
    #  - width: 640
    #    height: 480
    #    method: scale
    #  - width: 800
    #    height: 600
    #    method: scale

    # Is the preview URL API enabled?
    #
    # 'false' by default: uncomment the following to enable it (and specify a
    # url_preview_ip_range_blacklist blacklist).
    #
    #url_preview_enabled: true

    # List of IP address CIDR ranges that the URL preview spider is denied
    # from accessing.  There are no defaults: you must explicitly
    # specify a list for URL previewing to work.  You should specify any
    # internal services in your network that you do not want synapse to try
    # to connect to, otherwise anyone in any Matrix room could cause your
    # synapse to issue arbitrary GET requests to your internal services,
    # causing serious security issues.
    #
    # (0.0.0.0 and :: are always blacklisted, whether or not they are explicitly
    # listed here, since they correspond to unroutable addresses.)
    #
    # This must be specified if url_preview_enabled is set. It is recommended that
    # you uncomment the following list as a starting point.
    #
    # Note: The value is ignored when an HTTP proxy is in use
    #
    #url_preview_ip_range_blacklist:
    #  - '127.0.0.0/8'
    #  - '10.0.0.0/8'
    #  - '172.16.0.0/12'
    #  - '192.168.0.0/16'
    #  - '100.64.0.0/10'
    #  - '192.0.0.0/24'
    #  - '169.254.0.0/16'
    #  - '192.88.99.0/24'
    #  - '198.18.0.0/15'
    #  - '192.0.2.0/24'
    #  - '198.51.100.0/24'
    #  - '203.0.113.0/24'
    #  - '224.0.0.0/4'
    #  - '::1/128'
    #  - 'fe80::/10'
    #  - 'fc00::/7'
    #  - '2001:db8::/32'
    #  - 'ff00::/8'
    #  - 'fec0::/10'

    # List of IP address CIDR ranges that the URL preview spider is allowed
    # to access even if they are specified in url_preview_ip_range_blacklist.
    # This is useful for specifying exceptions to wide-ranging blacklisted
    # target IP ranges - e.g. for enabling URL previews for a specific private
    # website only visible in your network.
    #
    #url_preview_ip_range_whitelist:
    #   - '192.168.1.1'

    # Optional list of URL matches that the URL preview spider is
    # denied from accessing.  You should use url_preview_ip_range_blacklist
    # in preference to this, otherwise someone could define a public DNS
    # entry that points to a private IP address and circumvent the blacklist.
    # This is more useful if you know there is an entire shape of URL that
    # you know that will never want synapse to try to spider.
    #
    # Each list entry is a dictionary of url component attributes as returned
    # by urlparse.urlsplit as applied to the absolute form of the URL.  See
    # https://docs.python.org/2/library/urlparse.html#urlparse.urlsplit
    # The values of the dictionary are treated as an filename match pattern
    # applied to that component of URLs, unless they start with a ^ in which
    # case they are treated as a regular expression match.  If all the
    # specified component matches for a given list item succeed, the URL is
    # blacklisted.
    #
    #url_preview_url_blacklist:
    #  # blacklist any URL with a username in its URI
    #  - username: '*'
    #
    #  # blacklist all *.google.com URLs
    #  - netloc: 'google.com'
    #  - netloc: '*.google.com'
    #
    #  # blacklist all plain HTTP URLs
    #  - scheme: 'http'
    #
    #  # blacklist http(s)://www.acme.com/foo
    #  - netloc: 'www.acme.com'
    #    path: '/foo'
    #
    #  # blacklist any URL with a literal IPv4 address
    #  - netloc: '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'

    # The largest allowed URL preview spidering size in bytes
    #
    #max_spider_size: 10M

    # A list of values for the Accept-Language HTTP header used when
    # downloading webpages during URL preview generation. This allows
    # Synapse to specify the preferred languages that URL previews should
    # be in when communicating with remote servers.
    #
    # Each value is a IETF language tag; a 2-3 letter identifier for a
    # language, optionally followed by subtags separated by '-', specifying
    # a country or region variant.
    #
    # Multiple values can be provided, and a weight can be added to each by
    # using quality value syntax (;q=). '*' translates to any language.
    #
    # Defaults to "en".
    #
    # Example:
    #
    # url_preview_accept_language:
    #   - en-UK
    #   - en-US;q=0.9
    #   - fr;q=0.8
    #   - *;q=0.7
    #
    url_preview_accept_language:
    #   - en

    # oEmbed allows for easier embedding content from a website. It can be
    # used for generating URLs previews of services which support it.
    #
    oembed:
      # A default list of oEmbed providers is included with Synapse.
      #
      # Uncomment the following to disable using these default oEmbed URLs.
      # Defaults to 'false'.
      #
      #disable_default_providers: true

      # Additional files with oEmbed configuration (each should be in the
      # form of providers.json).
      #
      # By default, this list is empty (so only the default providers.json
      # is used).
      #
      #additional_providers:
      #  - oembed/my_providers.json

    ## Captcha ##
    # See docs/CAPTCHA_SETUP.md for full details of configuring this.

    # This homeserver's ReCAPTCHA public key. Must be specified if
    # enable_registration_captcha is enabled.
    #
    #recaptcha_public_key: "YOUR_PUBLIC_KEY"

    # This homeserver's ReCAPTCHA private key. Must be specified if
    # enable_registration_captcha is enabled.
    #
    #recaptcha_private_key: "YOUR_PRIVATE_KEY"

    # Uncomment to enable ReCaptcha checks when registering, preventing signup
    # unless a captcha is answered. Requires a valid ReCaptcha
    # public/private key. Defaults to 'false'.
    #
    #enable_registration_captcha: true

    # The API endpoint to use for verifying m.login.recaptcha responses.
    # Defaults to "https://www.recaptcha.net/recaptcha/api/siteverify".
    #
    #recaptcha_siteverify_api: "https://my.recaptcha.site"

    ## TURN ##

    # The public URIs of the TURN server to give to clients
    #
    #turn_uris: []

    # The shared secret used to compute passwords for the TURN server
    #
    #turn_shared_secret: "YOUR_SHARED_SECRET"

    # The Username and password if the TURN server needs them and
    # does not use a token
    #
    #turn_username: "TURNSERVER_USERNAME"
    #turn_password: "TURNSERVER_PASSWORD"

    # How long generated TURN credentials last
    #
    #turn_user_lifetime: 1h

    # Whether guests should be allowed to use the TURN server.
    # This defaults to True, otherwise VoIP will be unreliable for guests.
    # However, it does introduce a slight security risk as it allows users to
    # connect to arbitrary endpoints without having first signed up for a
    # valid account (e.g. by passing a CAPTCHA).
    #
    #turn_allow_guests: true

    ## Registration ##
    #
    # Registration can be rate-limited using the parameters in the "Ratelimiting"
    # section of this file.

    # Enable registration for new users.
    #
    #enable_registration: false

    # Time that a user's session remains valid for, after they log in.
    #
    # Note that this is not currently compatible with guest logins.
    #
    # Note also that this is calculated at login time: changes are not applied
    # retrospectively to users who have already logged in.
    #
    # By default, this is infinite.
    #
    #session_lifetime: 24h

    # The user must provide all of the below types of 3PID when registering.
    #
    #registrations_require_3pid:
    #  - email
    #  - msisdn

    # Explicitly disable asking for MSISDNs from the registration
    # flow (overrides registrations_require_3pid if MSISDNs are set as required)
    #
    #disable_msisdn_registration: true

    # Mandate that users are only allowed to associate certain formats of
    # 3PIDs with accounts on this server.
    #
    #allowed_local_3pids:
    #  - medium: email
    #    pattern: '^[^@]+@matrix\.org$'
    #  - medium: email
    #    pattern: '^[^@]+@vector\.im$'
    #  - medium: msisdn
    #    pattern: '\+44'

    # Enable 3PIDs lookup requests to identity servers from this server.
    #
    #enable_3pid_lookup: true

    # Require users to submit a token during registration.
    # Tokens can be managed using the admin API:
    # https://matrix-org.github.io/synapse/latest/usage/administration/admin_api/registration_tokens.html
    # Note that `enable_registration` must be set to `true`.
    # Disabling this option will not delete any tokens previously generated.
    # Defaults to false. Uncomment the following to require tokens:
    #
    #registration_requires_token: true

    # If set, allows registration of standard or admin accounts by anyone who
    # has the shared secret, even if registration is otherwise disabled.
    #
    #registration_shared_secret: <PRIVATE STRING>

    # Set the number of bcrypt rounds used to generate password hash.
    # Larger numbers increase the work factor needed to generate the hash.
    # The default number is 12 (which equates to 2^12 rounds).
    # N.B. that increasing this will exponentially increase the time required
    # to register or login - e.g. 24 => 2^24 rounds which will take >20 mins.
    #
    #bcrypt_rounds: 12

    # Allows users to register as guests without a password/email/etc, and
    # participate in rooms hosted on this server which have been made
    # accessible to anonymous users.
    #
    #allow_guest_access: false

    # The identity server which we suggest that clients should use when users log
    # in on this server.
    #
    # (By default, no suggestion is made, so it is left up to the client.
    # This setting is ignored unless public_baseurl is also set.)
    #
    #default_identity_server: https://matrix.org

    # Handle threepid (email/phone etc) registration and password resets through a set of
    # *trusted* identity servers. Note that this allows the configured identity server to
    # reset passwords for accounts!
    #
    # Be aware that if `email` is not set, and SMTP options have not been
    # configured in the email config block, registration and user password resets via
    # email will be globally disabled.
    #
    # Additionally, if `msisdn` is not set, registration and password resets via msisdn
    # will be disabled regardless, and users will not be able to associate an msisdn
    # identifier to their account. This is due to Synapse currently not supporting
    # any method of sending SMS messages on its own.
    #
    # To enable using an identity server for operations regarding a particular third-party
    # identifier type, set the value to the URL of that identity server as shown in the
    # examples below.
    #
    # Servers handling the these requests must answer the `/requestToken` endpoints defined
    # by the Matrix Identity Service API specification:
    # https://matrix.org/docs/spec/identity_service/latest
    #
    # If a delegate is specified, the config option public_baseurl must also be filled out.
    #
    account_threepid_delegates:
        #email: https://example.com     # Delegate email sending to example.com
        #msisdn: http://localhost:8090  # Delegate SMS sending to this local process

    # Whether users are allowed to change their displayname after it has
    # been initially set. Useful when provisioning users based on the
    # contents of a third-party directory.
    #
    # Does not apply to server administrators. Defaults to 'true'
    #
    #enable_set_displayname: false

    # Whether users are allowed to change their avatar after it has been
    # initially set. Useful when provisioning users based on the contents
    # of a third-party directory.
    #
    # Does not apply to server administrators. Defaults to 'true'
    #
    #enable_set_avatar_url: false

    # Whether users can change the 3PIDs associated with their accounts
    # (email address and msisdn).
    #
    # Defaults to 'true'
    #
    #enable_3pid_changes: false

    # Users who register on this homeserver will automatically be joined
    # to these rooms.
    #
    # By default, any room aliases included in this list will be created
    # as a publicly joinable room when the first user registers for the
    # homeserver. This behaviour can be customised with the settings below.
    # If the room already exists, make certain it is a publicly joinable
    # room. The join rule of the room must be set to 'public'.
    #
    #auto_join_rooms:
    #  - "#example:example.com"

    # Where auto_join_rooms are specified, setting this flag ensures that the
    # the rooms exist by creating them when the first user on the
    # homeserver registers.
    #
    # By default the auto-created rooms are publicly joinable from any federated
    # server. Use the autocreate_auto_join_rooms_federated and
    # autocreate_auto_join_room_preset settings below to customise this behaviour.
    #
    # Setting to false means that if the rooms are not manually created,
    # users cannot be auto-joined since they do not exist.
    #
    # Defaults to true. Uncomment the following line to disable automatically
    # creating auto-join rooms.
    #
    #autocreate_auto_join_rooms: false

    # Whether the auto_join_rooms that are auto-created are available via
    # federation. Only has an effect if autocreate_auto_join_rooms is true.
    #
    # Note that whether a room is federated cannot be modified after
    # creation.
    #
    # Defaults to true: the room will be joinable from other servers.
    # Uncomment the following to prevent users from other homeservers from
    # joining these rooms.
    #
    #autocreate_auto_join_rooms_federated: false

    # The room preset to use when auto-creating one of auto_join_rooms. Only has an
    # effect if autocreate_auto_join_rooms is true.
    #
    # This can be one of "public_chat", "private_chat", or "trusted_private_chat".
    # If a value of "private_chat" or "trusted_private_chat" is used then
    # auto_join_mxid_localpart must also be configured.
    #
    # Defaults to "public_chat", meaning that the room is joinable by anyone, including
    # federated servers if autocreate_auto_join_rooms_federated is true (the default).
    # Uncomment the following to require an invitation to join these rooms.
    #
    #autocreate_auto_join_room_preset: private_chat

    # The local part of the user id which is used to create auto_join_rooms if
    # autocreate_auto_join_rooms is true. If this is not provided then the
    # initial user account that registers will be used to create the rooms.
    #
    # The user id is also used to invite new users to any auto-join rooms which
    # are set to invite-only.
    #
    # It *must* be configured if autocreate_auto_join_room_preset is set to
    # "private_chat" or "trusted_private_chat".
    #
    # Note that this must be specified in order for new users to be correctly
    # invited to any auto-join rooms which have been set to invite-only (either
    # at the time of creation or subsequently).
    #
    # Note that, if the room already exists, this user must be joined and
    # have the appropriate permissions to invite new members.
    #
    #auto_join_mxid_localpart: system

    # When auto_join_rooms is specified, setting this flag to false prevents
    # guest accounts from being automatically joined to the rooms.
    #
    # Defaults to true.
    #
    #auto_join_rooms_for_guests: false

    ## Metrics ###

    # Enable collection and rendering of performance metrics
    #
    #enable_metrics: false

    # Enable sentry integration
    # NOTE: While attempts are made to ensure that the logs don't contain
    # any sensitive information, this cannot be guaranteed. By enabling
    # this option the sentry server may therefore receive sensitive
    # information, and it in turn may then diseminate sensitive information
    # through insecure notification channels if so configured.
    #
    #sentry:
    #    dsn: "..."

    # Flags to enable Prometheus metrics which are not suitable to be
    # enabled by default, either for performance reasons or limited use.
    #
    metrics_flags:
        # Publish synapse_federation_known_servers, a gauge of the number of
        # servers this homeserver knows about, including itself. May cause
        # performance problems on large homeservers.
        #
        #known_servers: true

    # Whether or not to report anonymized homeserver usage statistics.
    #
    #report_stats: true|false

    # The endpoint to report the anonymized homeserver usage statistics to.
    # Defaults to https://matrix.org/report-usage-stats/push
    #
    #report_stats_endpoint: https://example.com/report-usage-stats/push

    ## API Configuration ##

    # Controls for the state that is shared with users who receive an invite
    # to a room
    #
    room_prejoin_state:
       # By default, the following state event types are shared with users who
       # receive invites to the room:
       #
       # - m.room.join_rules
       # - m.room.canonical_alias
       # - m.room.avatar
       # - m.room.encryption
       # - m.room.name
       # - m.room.create
       #
       # Uncomment the following to disable these defaults (so that only the event
       # types listed in 'additional_event_types' are shared). Defaults to 'false'.
       #
       #disable_default_event_types: true

       # Additional state event types to share with users when they are invited
       # to a room.
       #
       # By default, this list is empty (so only the default event types are shared).
       #
       #additional_event_types:
       #  - org.example.custom.event.type

    # A list of application service config files to use
    #
    #app_service_config_files:
    #  - app_service_1.yaml
    #  - app_service_2.yaml

    # Uncomment to enable tracking of application service IP addresses. Implicitly
    # enables MAU tracking for application service users.
    #
    #track_appservice_user_ips: true

    # a secret which is used to sign access tokens. If none is specified,
    # the registration_shared_secret is used, if one is given; otherwise,
    # a secret key is derived from the signing key.
    #
    #macaroon_secret_key: <PRIVATE STRING>

    # a secret which is used to calculate HMACs for form values, to stop
    # falsification of values. Must be specified for the User Consent
    # forms to work.
    #
    #form_secret: <PRIVATE STRING>

    ## Signing Keys ##

    # Path to the signing key to sign messages with
    #
    signing_key_path: "CONFDIR/SERVERNAME.signing.key"

    # The keys that the server used to sign messages with but won't use
    # to sign new messages.
    #
    old_signing_keys:
      # For each key, `key` should be the base64-encoded public key, and
      # `expired_ts`should be the time (in milliseconds since the unix epoch) that
      # it was last used.
      #
      # It is possible to build an entry from an old signing.key file using the
      # `export_signing_key` script which is provided with synapse.
      #
      # For example:
      #
      #"ed25519:id": { key: "base64string", expired_ts: 123456789123 }

    # How long key response published by this server is valid for.
    # Used to set the valid_until_ts in /key/v2 APIs.
    # Determines how quickly servers will query to check which keys
    # are still valid.
    #
    #key_refresh_interval: 1d

    # The trusted servers to download signing keys from.
    #
    # When we need to fetch a signing key, each server is tried in parallel.
    #
    # Normally, the connection to the key server is validated via TLS certificates.
    # Additional security can be provided by configuring a `verify key`, which
    # will make synapse check that the response is signed by that key.
    #
    # This setting supercedes an older setting named `perspectives`. The old format
    # is still supported for backwards-compatibility, but it is deprecated.
    #
    # 'trusted_key_servers' defaults to matrix.org, but using it will generate a
    # warning on start-up. To suppress this warning, set
    # 'suppress_key_server_warning' to true.
    #
    # Options for each entry in the list include:
    #
    #    server_name: the name of the server. required.
    #
    #    verify_keys: an optional map from key id to base64-encoded public key.
    #       If specified, we will check that the response is signed by at least
    #       one of the given keys.
    #
    #    accept_keys_insecurely: a boolean. Normally, if `verify_keys` is unset,
    #       and federation_verify_certificates is not `true`, synapse will refuse
    #       to start, because this would allow anyone who can spoof DNS responses
    #       to masquerade as the trusted key server. If you know what you are doing
    #       and are sure that your network environment provides a secure connection
    #       to the key server, you can set this to `true` to override this
    #       behaviour.
    #
    # An example configuration might look like:
    #
    #trusted_key_servers:
    #  - server_name: "my_trusted_server.example.com"
    #    verify_keys:
    #      "ed25519:auto": "abcdefghijklmnopqrstuvwxyzabcdefghijklmopqr"
    #  - server_name: "my_other_trusted_server.example.com"
    #
    trusted_key_servers:
      - server_name: "matrix.org"

    # Uncomment the following to disable the warning that is emitted when the
    # trusted_key_servers include 'matrix.org'. See above.
    #
    #suppress_key_server_warning: true

    # The signing keys to use when acting as a trusted key server. If not specified
    # defaults to the server signing key.
    #
    # Can contain multiple keys, one per line.
    #
    #key_server_signing_keys_path: "key_server_signing_keys.key"

    ## Single sign-on integration ##

    # The following settings can be used to make Synapse use a single sign-on
    # provider for authentication, instead of its internal password database.
    #
    # You will probably also want to set the following options to `false` to
    # disable the regular login/registration flows:
    #   * enable_registration
    #   * password_config.enabled
    #
    # You will also want to investigate the settings under the "sso" configuration
    # section below.

    # Enable SAML2 for registration and login. Uses pysaml2.
    #
    # At least one of `sp_config` or `config_path` must be set in this section to
    # enable SAML login.
    #
    # Once SAML support is enabled, a metadata file will be exposed at
    # https://<server>:<port>/_synapse/client/saml2/metadata.xml, which you may be able to
    # use to configure your SAML IdP with. Alternatively, you can manually configure
    # the IdP to use an ACS location of
    # https://<server>:<port>/_synapse/client/saml2/authn_response.
    #
    saml2_config:
      # `sp_config` is the configuration for the pysaml2 Service Provider.
      # See pysaml2 docs for format of config.
      #
      # Default values will be used for the 'entityid' and 'service' settings,
      # so it is not normally necessary to specify them unless you need to
      # override them.
      #
      sp_config:
        # Point this to the IdP's metadata. You must provide either a local
        # file via the `local` attribute or (preferably) a URL via the
        # `remote` attribute.
        #
        #metadata:
        #  local: ["saml2/idp.xml"]
        #  remote:
        #    - url: https://our_idp/metadata.xml

        # Allowed clock difference in seconds between the homeserver and IdP.
        #
        # Uncomment the below to increase the accepted time difference from 0 to 3 seconds.
        #
        #accepted_time_diff: 3

        # By default, the user has to go to our login page first. If you'd like
        # to allow IdP-initiated login, set 'allow_unsolicited: true' in a
        # 'service.sp' section:
        #
        #service:
        #  sp:
        #    allow_unsolicited: true

        # The examples below are just used to generate our metadata xml, and you
        # may well not need them, depending on your setup. Alternatively you
        # may need a whole lot more detail - see the pysaml2 docs!

        #description: ["My awesome SP", "en"]
        #name: ["Test SP", "en"]

        #ui_info:
        #  display_name:
        #    - lang: en
        #      text: "Display Name is the descriptive name of your service."
        #  description:
        #    - lang: en
        #      text: "Description should be a short paragraph explaining the purpose of the service."
        #  information_url:
        #    - lang: en
        #      text: "https://example.com/terms-of-service"
        #  privacy_statement_url:
        #    - lang: en
        #      text: "https://example.com/privacy-policy"
        #  keywords:
        #    - lang: en
        #      text: ["Matrix", "Element"]
        #  logo:
        #    - lang: en
        #      text: "https://example.com/logo.svg"
        #      width: "200"
        #      height: "80"

        #organization:
        #  name: Example com
        #  display_name:
        #    - ["Example co", "en"]
        #  url: "http://example.com"

        #contact_person:
        #  - given_name: Bob
        #    sur_name: "the Sysadmin"
        #    email_address": ["admin@example.com"]
        #    contact_type": technical

      # Instead of putting the config inline as above, you can specify a
      # separate pysaml2 configuration file:
      #
      #config_path: "CONFDIR/sp_conf.py"

      # The lifetime of a SAML session. This defines how long a user has to
      # complete the authentication process, if allow_unsolicited is unset.
      # The default is 15 minutes.
      #
      #saml_session_lifetime: 5m

      # An external module can be provided here as a custom solution to
      # mapping attributes returned from a saml provider onto a matrix user.
      #
      user_mapping_provider:
        # The custom module's class. Uncomment to use a custom module.
        #
        #module: mapping_provider.SamlMappingProvider

        # Custom configuration values for the module. Below options are
        # intended for the built-in provider, they should be changed if
        # using a custom module. This section will be passed as a Python
        # dictionary to the module's `parse_config` method.
        #
        config:
          # The SAML attribute (after mapping via the attribute maps) to use
          # to derive the Matrix ID from. 'uid' by default.
          #
          # Note: This used to be configured by the
          # saml2_config.mxid_source_attribute option. If that is still
          # defined, its value will be used instead.
          #
          #mxid_source_attribute: displayName

          # The mapping system to use for mapping the saml attribute onto a
          # matrix ID.
          #
          # Options include:
          #  * 'hexencode' (which maps unpermitted characters to '=xx')
          #  * 'dotreplace' (which replaces unpermitted characters with
          #     '.').
          # The default is 'hexencode'.
          #
          # Note: This used to be configured by the
          # saml2_config.mxid_mapping option. If that is still defined, its
          # value will be used instead.
          #
          #mxid_mapping: dotreplace

      # In previous versions of synapse, the mapping from SAML attribute to
      # MXID was always calculated dynamically rather than stored in a
      # table. For backwards- compatibility, we will look for user_ids
      # matching such a pattern before creating a new account.
      #
      # This setting controls the SAML attribute which will be used for this
      # backwards-compatibility lookup. Typically it should be 'uid', but if
      # the attribute maps are changed, it may be necessary to change it.
      #
      # The default is 'uid'.
      #
      #grandfathered_mxid_source_attribute: upn

      # It is possible to configure Synapse to only allow logins if SAML attributes
      # match particular values. The requirements can be listed under
      # `attribute_requirements` as shown below. All of the listed attributes must
      # match for the login to be permitted.
      #
      #attribute_requirements:
      #  - attribute: userGroup
      #    value: "staff"
      #  - attribute: department
      #    value: "sales"

      # If the metadata XML contains multiple IdP entities then the `idp_entityid`
      # option must be set to the entity to redirect users to.
      #
      # Most deployments only have a single IdP entity and so should omit this
      # option.
      #
      #idp_entityid: 'https://our_idp/entityid'

    # List of OpenID Connect (OIDC) / OAuth 2.0 identity providers, for registration
    # and login.
    #
    # Options for each entry include:
    #
    #   idp_id: a unique identifier for this identity provider. Used internally
    #       by Synapse; should be a single word such as 'github'.
    #
    #       Note that, if this is changed, users authenticating via that provider
    #       will no longer be recognised as the same user!
    #
    #       (Use "oidc" here if you are migrating from an old "oidc_config"
    #       configuration.)
    #
    #   idp_name: A user-facing name for this identity provider, which is used to
    #       offer the user a choice of login mechanisms.
    #
    #   idp_icon: An optional icon for this identity provider, which is presented
    #       by clients and Synapse's own IdP picker page. If given, must be an
    #       MXC URI of the format mxc://<server-name>/<media-id>. (An easy way to
    #       obtain such an MXC URI is to upload an image to an (unencrypted) room
    #       and then copy the "url" from the source of the event.)
    #
    #   idp_brand: An optional brand for this identity provider, allowing clients
    #       to style the login flow according to the identity provider in question.
    #       See the spec for possible options here.
    #
    #   discover: set to 'false' to disable the use of the OIDC discovery mechanism
    #       to discover endpoints. Defaults to true.
    #
    #   issuer: Required. The OIDC issuer. Used to validate tokens and (if discovery
    #       is enabled) to discover the provider's endpoints.
    #
    #   client_id: Required. oauth2 client id to use.
    #
    #   client_secret: oauth2 client secret to use. May be omitted if
    #        client_secret_jwt_key is given, or if client_auth_method is 'none'.
    #
    #   client_secret_jwt_key: Alternative to client_secret: details of a key used
    #      to create a JSON Web Token to be used as an OAuth2 client secret. If
    #      given, must be a dictionary with the following properties:
    #
    #          key: a pem-encoded signing key. Must be a suitable key for the
    #              algorithm specified. Required unless 'key_file' is given.
    #
    #          key_file: the path to file containing a pem-encoded signing key file.
    #              Required unless 'key' is given.
    #
    #          jwt_header: a dictionary giving properties to include in the JWT
    #              header. Must include the key 'alg', giving the algorithm used to
    #              sign the JWT, such as "ES256", using the JWA identifiers in
    #              RFC7518.
    #
    #          jwt_payload: an optional dictionary giving properties to include in
    #              the JWT payload. Normally this should include an 'iss' key.
    #
    #   client_auth_method: auth method to use when exchanging the token. Valid
    #       values are 'client_secret_basic' (default), 'client_secret_post' and
    #       'none'.
    #
    #   scopes: list of scopes to request. This should normally include the "openid"
    #       scope. Defaults to ["openid"].
    #
    #   authorization_endpoint: the oauth2 authorization endpoint. Required if
    #       provider discovery is disabled.
    #
    #   token_endpoint: the oauth2 token endpoint. Required if provider discovery is
    #       disabled.
    #
    #   userinfo_endpoint: the OIDC userinfo endpoint. Required if discovery is
    #       disabled and the 'openid' scope is not requested.
    #
    #   jwks_uri: URI where to fetch the JWKS. Required if discovery is disabled and
    #       the 'openid' scope is used.
    #
    #   skip_verification: set to 'true' to skip metadata verification. Use this if
    #       you are connecting to a provider that is not OpenID Connect compliant.
    #       Defaults to false. Avoid this in production.
    #
    #   user_profile_method: Whether to fetch the user profile from the userinfo
    #       endpoint. Valid values are: 'auto' or 'userinfo_endpoint'.
    #
    #       Defaults to 'auto', which fetches the userinfo endpoint if 'openid' is
    #       included in 'scopes'. Set to 'userinfo_endpoint' to always fetch the
    #       userinfo endpoint.
    #
    #   allow_existing_users: set to 'true' to allow a user logging in via OIDC to
    #       match a pre-existing account instead of failing. This could be used if
    #       switching from password logins to OIDC. Defaults to false.
    #
    #   user_mapping_provider: Configuration for how attributes returned from a OIDC
    #       provider are mapped onto a matrix user. This setting has the following
    #       sub-properties:
    #
    #       module: The class name of a custom mapping module. Default is
    #           'synapse.handlers.oidc.JinjaOidcMappingProvider'.
    #           See https://matrix-org.github.io/synapse/latest/sso_mapping_providers.html#openid-mapping-providers
    #           for information on implementing a custom mapping provider.
    #
    #       config: Configuration for the mapping provider module. This section will
    #           be passed as a Python dictionary to the user mapping provider
    #           module's `parse_config` method.
    #
    #           For the default provider, the following settings are available:
    #
    #             subject_claim: name of the claim containing a unique identifier
    #                 for the user. Defaults to 'sub', which OpenID Connect
    #                 compliant providers should provide.
    #
    #             localpart_template: Jinja2 template for the localpart of the MXID.
    #                 If this is not set, the user will be prompted to choose their
    #                 own username (see 'sso_auth_account_details.html' in the 'sso'
    #                 section of this file).
    #
    #             display_name_template: Jinja2 template for the display name to set
    #                 on first login. If unset, no displayname will be set.
    #
    #             email_template: Jinja2 template for the email address of the user.
    #                 If unset, no email address will be added to the account.
    #
    #             extra_attributes: a map of Jinja2 templates for extra attributes
    #                 to send back to the client during login.
    #                 Note that these are non-standard and clients will ignore them
    #                 without modifications.
    #
    #           When rendering, the Jinja2 templates are given a 'user' variable,
    #           which is set to the claims returned by the UserInfo Endpoint and/or
    #           in the ID Token.
    #
    #   It is possible to configure Synapse to only allow logins if certain attributes
    #   match particular values in the OIDC userinfo. The requirements can be listed under
    #   `attribute_requirements` as shown below. All of the listed attributes must
    #   match for the login to be permitted. Additional attributes can be added to
    #   userinfo by expanding the `scopes` section of the OIDC config to retrieve
    #   additional information from the OIDC provider.
    #
    #   If the OIDC claim is a list, then the attribute must match any value in the list.
    #   Otherwise, it must exactly match the value of the claim. Using the example
    #   below, the `family_name` claim MUST be "Stephensson", but the `groups`
    #   claim MUST contain "admin".
    #
    #   attribute_requirements:
    #     - attribute: family_name
    #       value: "Stephensson"
    #     - attribute: groups
    #       value: "admin"
    #
    # See https://matrix-org.github.io/synapse/latest/openid.html
    # for information on how to configure these options.
    #
    # For backwards compatibility, it is also possible to configure a single OIDC
    # provider via an 'oidc_config' setting. This is now deprecated and admins are
    # advised to migrate to the 'oidc_providers' format. (When doing that migration,
    # use 'oidc' for the idp_id to ensure that existing users continue to be
    # recognised.)
    #
    oidc_providers:
      # Generic example
      #
      #- idp_id: my_idp
      #  idp_name: "My OpenID provider"
      #  idp_icon: "mxc://example.com/mediaid"
      #  discover: false
      #  issuer: "https://accounts.example.com/"
      #  client_id: "provided-by-your-issuer"
      #  client_secret: "provided-by-your-issuer"
      #  client_auth_method: client_secret_post
      #  scopes: ["openid", "profile"]
      #  authorization_endpoint: "https://accounts.example.com/oauth2/auth"
      #  token_endpoint: "https://accounts.example.com/oauth2/token"
      #  userinfo_endpoint: "https://accounts.example.com/userinfo"
      #  jwks_uri: "https://accounts.example.com/.well-known/jwks.json"
      #  skip_verification: true
      #  user_mapping_provider:
      #    config:
      #      subject_claim: "id"
      #      localpart_template: "{{ user.login }}"
      #      display_name_template: "{{ user.name }}"
      #      email_template: "{{ user.email }}"
      #  attribute_requirements:
      #    - attribute: userGroup
      #      value: "synapseUsers"

    # Enable Central Authentication Service (CAS) for registration and login.
    #
    cas_config:
      # Uncomment the following to enable authorization against a CAS server.
      # Defaults to false.
      #
      #enabled: true

      # The URL of the CAS authorization endpoint.
      #
      #server_url: "https://cas-server.com"

      # The attribute of the CAS response to use as the display name.
      #
      # If unset, no displayname will be set.
      #
      #displayname_attribute: name

      # It is possible to configure Synapse to only allow logins if CAS attributes
      # match particular values. All of the keys in the mapping below must exist
      # and the values must match the given value. Alternately if the given value
      # is None then any value is allowed (the attribute just must exist).
      # All of the listed attributes must match for the login to be permitted.
      #
      #required_attributes:
      #  userGroup: "staff"
      #  department: None

    # Additional settings to use with single-sign on systems such as OpenID Connect,
    # SAML2 and CAS.
    #
    # Server admins can configure custom templates for pages related to SSO. See
    # https://matrix-org.github.io/synapse/latest/templates.html for more information.
    #
    sso:
        # A list of client URLs which are whitelisted so that the user does not
        # have to confirm giving access to their account to the URL. Any client
        # whose URL starts with an entry in the following list will not be subject
        # to an additional confirmation step after the SSO login is completed.
        #
        # WARNING: An entry such as "https://my.client" is insecure, because it
        # will also match "https://my.client.evil.site", exposing your users to
        # phishing attacks from evil.site. To avoid this, include a slash after the
        # hostname: "https://my.client/".
        #
        # If public_baseurl is set, then the login fallback page (used by clients
        # that don't natively support the required login flows) is whitelisted in
        # addition to any URLs in this list.
        #
        # By default, this list is empty.
        #
        #client_whitelist:
        #  - https://riot.im/develop
        #  - https://my.custom.client/

        # Uncomment to keep a user's profile fields in sync with information from
        # the identity provider. Currently only syncing the displayname is
        # supported. Fields are checked on every SSO login, and are updated
        # if necessary.
        #
        # Note that enabling this option will override user profile information,
        # regardless of whether users have opted-out of syncing that
        # information when first signing in. Defaults to false.
        #
        #update_profile_information: true

    # JSON web token integration. The following settings can be used to make
    # Synapse JSON web tokens for authentication, instead of its internal
    # password database.
    #
    # Each JSON Web Token needs to contain a "sub" (subject) claim, which is
    # used as the localpart of the mxid.
    #
    # Additionally, the expiration time ("exp"), not before time ("nbf"),
    # and issued at ("iat") claims are validated if present.
    #
    # Note that this is a non-standard login type and client support is
    # expected to be non-existent.
    #
    # See https://matrix-org.github.io/synapse/latest/jwt.html.
    #
    #jwt_config:
        # Uncomment the following to enable authorization using JSON web
        # tokens. Defaults to false.
        #
        #enabled: true

        # This is either the private shared secret or the public key used to
        # decode the contents of the JSON web token.
        #
        # Required if 'enabled' is true.
        #
        #secret: "provided-by-your-issuer"

        # The algorithm used to sign the JSON web token.
        #
        # Supported algorithms are listed at
        # https://pyjwt.readthedocs.io/en/latest/algorithms.html
        #
        # Required if 'enabled' is true.
        #
        #algorithm: "provided-by-your-issuer"

        # The issuer to validate the "iss" claim against.
        #
        # Optional, if provided the "iss" claim will be required and
        # validated for all JSON web tokens.
        #
        #issuer: "provided-by-your-issuer"

        # A list of audiences to validate the "aud" claim against.
        #
        # Optional, if provided the "aud" claim will be required and
        # validated for all JSON web tokens.
        #
        # Note that if the "aud" claim is included in a JSON web token then
        # validation will fail without configuring audiences.
        #
        #audiences:
        #    - "provided-by-your-issuer"

    password_config:
       # Uncomment to disable password login
       #
       #enabled: false

       # Uncomment to disable authentication against the local password
       # database. This is ignored if `enabled` is false, and is only useful
       # if you have other password_providers.
       #
       #localdb_enabled: false

       # Uncomment and change to a secret random string for extra security.
       # DO NOT CHANGE THIS AFTER INITIAL SETUP!
       #
       #pepper: "EVEN_MORE_SECRET"

       # Define and enforce a password policy. Each parameter is optional.
       # This is an implementation of MSC2000.
       #
       policy:
          # Whether to enforce the password policy.
          # Defaults to 'false'.
          #
          #enabled: true

          # Minimum accepted length for a password.
          # Defaults to 0.
          #
          #minimum_length: 15

          # Whether a password must contain at least one digit.
          # Defaults to 'false'.
          #
          #require_digit: true

          # Whether a password must contain at least one symbol.
          # A symbol is any character that's not a number or a letter.
          # Defaults to 'false'.
          #
          #require_symbol: true

          # Whether a password must contain at least one lowercase letter.
          # Defaults to 'false'.
          #
          #require_lowercase: true

          # Whether a password must contain at least one uppercase letter.
          # Defaults to 'false'.
          #
          #require_uppercase: true

    ui_auth:
        # The amount of time to allow a user-interactive authentication session
        # to be active.
        #
        # This defaults to 0, meaning the user is queried for their credentials
        # before every action, but this can be overridden to allow a single
        # validation to be re-used.  This weakens the protections afforded by
        # the user-interactive authentication process, by allowing for multiple
        # (and potentially different) operations to use the same validation session.
        #
        # This is ignored for potentially "dangerous" operations (including
        # deactivating an account, modifying an account password, and
        # adding a 3PID).
        #
        # Uncomment below to allow for credential validation to last for 15
        # seconds.
        #
        #session_timeout: "15s"

    # Configuration for sending emails from Synapse.
    #
    # Server admins can configure custom templates for email content. See
    # https://matrix-org.github.io/synapse/latest/templates.html for more information.
    #
    email:
      # The hostname of the outgoing SMTP server to use. Defaults to 'localhost'.
      #
      #smtp_host: mail.server

      # The port on the mail server for outgoing SMTP. Defaults to 25.
      #
      #smtp_port: 587

      # Username/password for authentication to the SMTP server. By default, no
      # authentication is attempted.
      #
      #smtp_user: "exampleusername"
      #smtp_pass: "examplepassword"

      # Uncomment the following to require TLS transport security for SMTP.
      # By default, Synapse will connect over plain text, and will then switch to
      # TLS via STARTTLS *if the SMTP server supports it*. If this option is set,
      # Synapse will refuse to connect unless the server supports STARTTLS.
      #
      #require_transport_security: true

      # Uncomment the following to disable TLS for SMTP.
      #
      # By default, if the server supports TLS, it will be used, and the server
      # must present a certificate that is valid for 'smtp_host'. If this option
      # is set to false, TLS will not be used.
      #
      #enable_tls: false

      # notif_from defines the "From" address to use when sending emails.
      # It must be set if email sending is enabled.
      #
      # The placeholder '%(app)s' will be replaced by the application name,
      # which is normally 'app_name' (below), but may be overridden by the
      # Matrix client application.
      #
      # Note that the placeholder must be written '%(app)s', including the
      # trailing 's'.
      #
      #notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"

      # app_name defines the default value for '%(app)s' in notif_from and email
      # subjects. It defaults to 'Matrix'.
      #
      #app_name: my_branded_matrix_server

      # Uncomment the following to enable sending emails for messages that the user
      # has missed. Disabled by default.
      #
      #enable_notifs: true

      # Uncomment the following to disable automatic subscription to email
      # notifications for new users. Enabled by default.
      #
      #notif_for_new_users: false

      # Custom URL for client links within the email notifications. By default
      # links will be based on "https://matrix.to".
      #
      # (This setting used to be called riot_base_url; the old name is still
      # supported for backwards-compatibility but is now deprecated.)
      #
      #client_base_url: "http://localhost/riot"

      # Configure the time that a validation email will expire after sending.
      # Defaults to 1h.
      #
      #validation_token_lifetime: 15m

      # The web client location to direct users to during an invite. This is passed
      # to the identity server as the org.matrix.web_client_location key. Defaults
      # to unset, giving no guidance to the identity server.
      #
      #invite_client_location: https://app.element.io

      # Subjects to use when sending emails from Synapse.
      #
      # The placeholder '%(app)s' will be replaced with the value of the 'app_name'
      # setting above, or by a value dictated by the Matrix client application.
      #
      # If a subject isn't overridden in this configuration file, the value used as
      # its example will be used.
      #
      #subjects:

        # Subjects for notification emails.
        #
        # On top of the '%(app)s' placeholder, these can use the following
        # placeholders:
        #
        #   * '%(person)s', which will be replaced by the display name of the user(s)
        #      that sent the message(s), e.g. "Alice and Bob".
        #   * '%(room)s', which will be replaced by the name of the room the
        #      message(s) have been sent to, e.g. "My super room".
        #
        # See the example provided for each setting to see which placeholder can be
        # used and how to use them.
        #
        # Subject to use to notify about one message from one or more user(s) in a
        # room which has a name.
        #message_from_person_in_room: "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
        #
        # Subject to use to notify about one message from one or more user(s) in a
        # room which doesn't have a name.
        #message_from_person: "[%(app)s] You have a message on %(app)s from %(person)s..."
        #
        # Subject to use to notify about multiple messages from one or more users in
        # a room which doesn't have a name.
        #messages_from_person: "[%(app)s] You have messages on %(app)s from %(person)s..."
        #
        # Subject to use to notify about multiple messages in a room which has a
        # name.
        #messages_in_room: "[%(app)s] You have messages on %(app)s in the %(room)s room..."
        #
        # Subject to use to notify about multiple messages in multiple rooms.
        #messages_in_room_and_others: "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
        #
        # Subject to use to notify about multiple messages from multiple persons in
        # multiple rooms. This is similar to the setting above except it's used when
        # the room in which the notification was triggered has no name.
        #messages_from_person_and_others: "[%(app)s] You have messages on %(app)s from %(person)s and others..."
        #
        # Subject to use to notify about an invite to a room which has a name.
        #invite_from_person_to_room: "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
        #
        # Subject to use to notify about an invite to a room which doesn't have a
        # name.
        #invite_from_person: "[%(app)s] %(person)s has invited you to chat on %(app)s..."

        # Subject for emails related to account administration.
        #
        # On top of the '%(app)s' placeholder, these one can use the
        # '%(server_name)s' placeholder, which will be replaced by the value of the
        # 'server_name' setting in your Synapse configuration.
        #
        # Subject to use when sending a password reset email.
        #password_reset: "[%(server_name)s] Password reset"
        #
        # Subject to use when sending a verification email to assert an address's
        # ownership.
        #email_validation: "[%(server_name)s] Validate your email"

    ## Push ##

    push:
      # Clients requesting push notifications can either have the body of
      # the message sent in the notification poke along with other details
      # like the sender, or just the event ID and room ID (`event_id_only`).
      # If clients choose the former, this option controls whether the
      # notification request includes the content of the event (other details
      # like the sender are still included). For `event_id_only` push, it
      # has no effect.
      #
      # For modern android devices the notification content will still appear
      # because it is loaded by the app. iPhone, however will send a
      # notification saying only that a message arrived and who it came from.
      #
      # The default value is "true" to include message details. Uncomment to only
      # include the event ID and room ID in push notification payloads.
      #
      #include_content: false

      # When a push notification is received, an unread count is also sent.
      # This number can either be calculated as the number of unread messages
      # for the user, or the number of *rooms* the user has unread messages in.
      #
      # The default value is "true", meaning push clients will see the number of
      # rooms with unread messages in them. Uncomment to instead send the number
      # of unread messages.
      #
      #group_unread_count_by_room: false

    ## Rooms ##

    # Controls whether locally-created rooms should be end-to-end encrypted by
    # default.
    #
    # Possible options are "all", "invite", and "off". They are defined as:
    #
    # * "all": any locally-created room
    # * "invite": any room created with the "private_chat" or "trusted_private_chat"
    #             room creation presets
    # * "off": this option will take no effect
    #
    # The default value is "off".
    #
    # Note that this option will only affect rooms created after it is set. It
    # will also not affect rooms created by other servers.
    #
    #encryption_enabled_by_default_for_room_type: invite

    # Uncomment to allow non-server-admin users to create groups on this server
    #
    #enable_group_creation: true

    # If enabled, non server admins can only create groups with local parts
    # starting with this prefix
    #
    #group_creation_prefix: "unofficial_"

    # User Directory configuration
    #
    user_directory:
        # Defines whether users can search the user directory. If false then
        # empty responses are returned to all queries. Defaults to true.
        #
        # Uncomment to disable the user directory.
        #
        #enabled: false

        # Defines whether to search all users visible to your HS when searching
        # the user directory. If false, search results will only contain users
        # visible in public rooms and users sharing a room with the requester.
        # Defaults to false.
        #
        # NB. If you set this to true, and the last time the user_directory search
        # indexes were (re)built was before Synapse 1.44, you'll have to
        # rebuild the indexes in order to search through all known users.
        # These indexes are built the first time Synapse starts; admins can
        # manually trigger a rebuild following the instructions at
        #     https://matrix-org.github.io/synapse/latest/user_directory.html
        #
        # Uncomment to return search results containing all known users, even if that
        # user does not share a room with the requester.
        #
        #search_all_users: true

        # Defines whether to prefer local users in search query results.
        # If True, local users are more likely to appear above remote users
        # when searching the user directory. Defaults to false.
        #
        # Uncomment to prefer local over remote users in user directory search
        # results.
        #
        #prefer_local_users: true

    # User Consent configuration
    #
    # for detailed instructions, see
    # https://matrix-org.github.io/synapse/latest/consent_tracking.html
    #
    # Parts of this section are required if enabling the 'consent' resource under
    # 'listeners', in particular 'template_dir' and 'version'.
    #
    # 'template_dir' gives the location of the templates for the HTML forms.
    # This directory should contain one subdirectory per language (eg, 'en', 'fr'),
    # and each language directory should contain the policy document (named as
    # '<version>.html') and a success page (success.html).
    #
    # 'version' specifies the 'current' version of the policy document. It defines
    # the version to be served by the consent resource if there is no 'v'
    # parameter.
    #
    # 'server_notice_content', if enabled, will send a user a "Server Notice"
    # asking them to consent to the privacy policy. The 'server_notices' section
    # must also be configured for this to work. Notices will *not* be sent to
    # guest users unless 'send_server_notice_to_guests' is set to true.
    #
    # 'block_events_error', if set, will block any attempts to send events
    # until the user consents to the privacy policy. The value of the setting is
    # used as the text of the error.
    #
    # 'require_at_registration', if enabled, will add a step to the registration
    # process, similar to how captcha works. Users will be required to accept the
    # policy before their account is created.
    #
    # 'policy_name' is the display name of the policy users will see when registering
    # for an account. Has no effect unless `require_at_registration` is enabled.
    # Defaults to "Privacy Policy".
    #
    #user_consent:
    #  template_dir: res/templates/privacy
    #  version: 1.0
    #  server_notice_content:
    #    msgtype: m.text
    #    body: >-
    #      To continue using this homeserver you must review and agree to the
    #      terms and conditions at %(consent_uri)s
    #  send_server_notice_to_guests: true
    #  block_events_error: >-
    #    To continue using this homeserver you must review and agree to the
    #    terms and conditions at %(consent_uri)s
    #  require_at_registration: false
    #  policy_name: Privacy Policy
    #

    # Settings for local room and user statistics collection. See
    # https://matrix-org.github.io/synapse/latest/room_and_user_statistics.html.
    #
    stats:
      # Uncomment the following to disable room and user statistics. Note that doing
      # so may cause certain features (such as the room directory) not to work
      # correctly.
      #
      #enabled: false

    # Server Notices room configuration
    #
    # Uncomment this section to enable a room which can be used to send notices
    # from the server to users. It is a special room which cannot be left; notices
    # come from a special "notices" user id.
    #
    # If you uncomment this section, you *must* define the system_mxid_localpart
    # setting, which defines the id of the user which will be used to send the
    # notices.
    #
    # It's also possible to override the room name, the display name of the
    # "notices" user, and the avatar for the user.
    #
    #server_notices:
    #  system_mxid_localpart: notices
    #  system_mxid_display_name: "Server Notices"
    #  system_mxid_avatar_url: "mxc://server.com/oumMVlgDnLYFaPVkExemNVVZ"
    #  room_name: "Server Notices"

    # Uncomment to disable searching the public room list. When disabled
    # blocks searching local and remote room lists for local and remote
    # users by always returning an empty list for all queries.
    #
    #enable_room_list_search: false

    # The `alias_creation` option controls who's allowed to create aliases
    # on this server.
    #
    # The format of this option is a list of rules that contain globs that
    # match against user_id, room_id and the new alias (fully qualified with
    # server name). The action in the first rule that matches is taken,
    # which can currently either be "allow" or "deny".
    #
    # Missing user_id/room_id/alias fields default to "*".
    #
    # If no rules match the request is denied. An empty list means no one
    # can create aliases.
    #
    # Options for the rules include:
    #
    #   user_id: Matches against the creator of the alias
    #   alias: Matches against the alias being created
    #   room_id: Matches against the room ID the alias is being pointed at
    #   action: Whether to "allow" or "deny" the request if the rule matches
    #
    # The default is:
    #
    #alias_creation_rules:
    #  - user_id: "*"
    #    alias: "*"
    #    room_id: "*"
    #    action: allow

    # The `room_list_publication_rules` option controls who can publish and
    # which rooms can be published in the public room list.
    #
    # The format of this option is the same as that for
    # `alias_creation_rules`.
    #
    # If the room has one or more aliases associated with it, only one of
    # the aliases needs to match the alias rule. If there are no aliases
    # then only rules with `alias: *` match.
    #
    # If no rules match the request is denied. An empty list means no one
    # can publish rooms.
    #
    # Options for the rules include:
    #
    #   user_id: Matches against the creator of the alias
    #   room_id: Matches against the room ID being published
    #   alias: Matches against any current local or canonical aliases
    #            associated with the room
    #   action: Whether to "allow" or "deny" the request if the rule matches
    #
    # The default is:
    #
    #room_list_publication_rules:
    #  - user_id: "*"
    #    alias: "*"
    #    room_id: "*"
    #    action: allow

    ## Opentracing ##

    # These settings enable opentracing, which implements distributed tracing.
    # This allows you to observe the causal chains of events across servers
    # including requests, key lookups etc., across any server running
    # synapse or any other other services which supports opentracing
    # (specifically those implemented with Jaeger).
    #
    opentracing:
        # tracing is disabled by default. Uncomment the following line to enable it.
        #
        #enabled: true

        # The list of homeservers we wish to send and receive span contexts and span baggage.
        # See https://matrix-org.github.io/synapse/latest/opentracing.html.
        #
        # This is a list of regexes which are matched against the server_name of the
        # homeserver.
        #
        # By default, it is empty, so no servers are matched.
        #
        #homeserver_whitelist:
        #  - ".*"

        # A list of the matrix IDs of users whose requests will always be traced,
        # even if the tracing system would otherwise drop the traces due to
        # probabilistic sampling.
        #
        # By default, the list is empty.
        #
        #force_tracing_for_users:
        #  - "@user1:server_name"
        #  - "@user2:server_name"

        # Jaeger can be configured to sample traces at different rates.
        # All configuration options provided by Jaeger can be set here.
        # Jaeger's configuration is mostly related to trace sampling which
        # is documented here:
        # https://www.jaegertracing.io/docs/latest/sampling/.
        #
        #jaeger_config:
        #  sampler:
        #    type: const
        #    param: 1
        #  logging:
        #    false

    ## Workers ##

    # Disables sending of outbound federation transactions on the main process.
    # Uncomment if using a federation sender worker.
    #
    #send_federation: false

    # It is possible to run multiple federation sender workers, in which case the
    # work is balanced across them.
    #
    # This configuration must be shared between all federation sender workers, and if
    # changed all federation sender workers must be stopped at the same time and then
    # started, to ensure that all instances are running with the same config (otherwise
    # events may be dropped).
    #
    #federation_sender_instances:
    #  - federation_sender1

    # When using workers this should be a map from `worker_name` to the
    # HTTP replication listener of the worker, if configured.
    #
    #instance_map:
    #  worker1:
    #    host: localhost
    #    port: 8034

    # Experimental: When using workers you can define which workers should
    # handle event persistence and typing notifications. Any worker
    # specified here must also be in the `instance_map`.
    #
    #stream_writers:
    #  events: worker1
    #  typing: worker1

    # The worker that is used to run background tasks (e.g. cleaning up expired
    # data). If not provided this defaults to the main process.
    #
    #run_background_tasks_on: worker1

    # A shared secret used by the replication APIs to authenticate HTTP requests
    # from workers.
    #
    # By default this is unused and traffic is not authenticated.
    #
    #worker_replication_secret: ""

    # Configuration for Redis when using workers. This *must* be enabled when
    # using workers (unless using old style direct TCP configuration).
    #
    redis:
      # Uncomment the below to enable Redis support.
      #
      #enabled: true

      # Optional host and port to use to connect to redis. Defaults to
      # localhost and 6379
      #
      #host: localhost
      #port: 6379

      # Optional password if configured on the Redis instance
      #
      #password: <secret_password>

# Logging Sample Configuration File

Below is a sample logging configuration file. This file can be tweaked to control how your homeserver will output logs. A restart of the server is generally required to apply any changes made to this file. The value of the `log_config` option in your homeserver config should be the path to this file.

Note that a default logging configuration (shown below) is created automatically alongside the homeserver config when following the installation instructions. It should be named `<SERVERNAME>.log.config` by default.

    # Log configuration for Synapse.
    #
    # This is a YAML file containing a standard Python logging configuration
    # dictionary. See [1] for details on the valid settings.
    #
    # Synapse also supports structured logging for machine readable logs which can
    # be ingested by ELK stacks. See [2] for details.
    #
    # [1]: https://docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema
    # [2]: https://matrix-org.github.io/synapse/latest/structured_logging.html

    version: 1

    formatters:
        precise:
            format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'

    handlers:
        file:
            class: logging.handlers.TimedRotatingFileHandler
            formatter: precise
            filename: /var/log/matrix-synapse/homeserver.log
            when: midnight
            backupCount: 3  # Does not include the current log file.
            encoding: utf8

        # Default to buffering writes to log file for efficiency.
        # WARNING/ERROR logs will still be flushed immediately, but there will be a
        # delay (of up to `period` seconds, or until the buffer is full with
        # `capacity` messages) before INFO/DEBUG logs get written.
        buffer:
            class: synapse.logging.handlers.PeriodicallyFlushingMemoryHandler
            target: file

            # The capacity is the maximum number of log lines that are buffered
            # before being written to disk. Increasing this will lead to better
            # performance, at the expensive of it taking longer for log lines to
            # be written to disk.
            # This parameter is required.
            capacity: 10

            # Logs with a level at or above the flush level will cause the buffer to
            # be flushed immediately.
            # Default value: 40 (ERROR)
            # Other values: 50 (CRITICAL), 30 (WARNING), 20 (INFO), 10 (DEBUG)
            flushLevel: 30  # Flush immediately for WARNING logs and higher

            # The period of time, in seconds, between forced flushes.
            # Messages will not be delayed for longer than this time.
            # Default value: 5 seconds
            period: 5

        # A handler that writes logs to stderr. Unused by default, but can be used
        # instead of "buffer" and "file" in the logger handlers.
        console:
            class: logging.StreamHandler
            formatter: precise

    loggers:
        synapse.storage.SQL:
            # beware: increasing this to DEBUG will make synapse log sensitive
            # information such as access tokens.
            level: INFO

        twisted:
            # We send the twisted logging directly to the file handler,
            # to work around https://github.com/matrix-org/synapse/issues/3471
            # when using "buffer" logger. Use "console" to log to stderr instead.
            handlers: [file]
            propagate: false

    root:
        level: INFO

        # Write logs to the `buffer` handler, which will buffer them together in memory,
        # then write them to a file.
        #
        # Replace "buffer" with "console" to log to stderr instead. (Note that you'll
        # also need to update the configuration for the `twisted` logger above, in
        # this case.)
        #
        handlers: [buffer]

    disable_existing_loggers: false

# Structured Logging

A structured logging system can be useful when your logs are destined for a machine to parse and process. By maintaining its machine-readable characteristics, it enables more efficient searching and aggregations when consumed by software such as the "ELK stack".

Synapse's structured logging system is configured via the file that Synapse's `log_config` config option points to. The file should include a formatter which uses the `synapse.logging.TerseJsonFormatter` class included with Synapse and a handler which uses the above formatter.

There is also a `synapse.logging.JsonFormatter` option which does not include a timestamp in the resulting JSON. This is useful if the log ingester adds its own timestamp.

A structured logging configuration looks similar to the following:

    version: 1

    formatters:
        structured:
            class: synapse.logging.TerseJsonFormatter

    handlers:
        file:
            class: logging.handlers.TimedRotatingFileHandler
            formatter: structured
            filename: /path/to/my/logs/homeserver.log
            when: midnight
            backupCount: 3  # Does not include the current log file.
            encoding: utf8

    loggers:
        synapse:
            level: INFO
            handlers: [remote]
        synapse.storage.SQL:
            level: WARNING

The above logging config will set Synapse as 'INFO' logging level by default, with the SQL layer at 'WARNING', and will log to a file, stored as JSON.

It is also possible to figure Synapse to log to a remote endpoint by using the `synapse.logging.RemoteHandler` class included with Synapse. It takes the following arguments:

- `host`: Hostname or IP address of the log aggregator.
- `port`: Numerical port to contact on the host.
- `maximum_buffer`: (Optional, defaults to 1000) The maximum buffer size to allow.

A remote structured logging configuration looks similar to the following:

    version: 1

    formatters:
        structured:
            class: synapse.logging.TerseJsonFormatter

    handlers:
        remote:
            class: synapse.logging.RemoteHandler
            formatter: structured
            host: 10.1.2.3
            port: 9999

    loggers:
        synapse:
            level: INFO
            handlers: [remote]
        synapse.storage.SQL:
            level: WARNING

The above logging config will set Synapse as 'INFO' logging level by default, with the SQL layer at 'WARNING', and will log JSON formatted messages to a remote endpoint at 10.1.2.3:9999.

## Upgrading from legacy structured logging configuration

Versions of Synapse prior to v1.23.0 included a custom structured logging configuration which is deprecated. It used a `structured: true` flag and configured `drains` instead of `handlers` and `formatters`.

Synapse currently automatically converts the old configuration to the new configuration, but this will be removed in a future version of Synapse. The following reference can be used to update your configuration. Based on the drain `type`, we can pick a new handler:

1. For a type of `console`, `console_json`, or `console_json_terse`: a handler with a class of `logging.StreamHandler` and a `stream` of `ext://sys.stdout` or `ext://sys.stderr` should be used.
2. For a type of `file` or `file_json`: a handler of `logging.FileHandler` with a location of the file path should be used.
3. For a type of `network_json_terse`: a handler of `synapse.logging.RemoteHandler` with the host and port should be used.

Then based on the drain `type` we can pick a new formatter:

1. For a type of `console` or `file` no formatter is necessary.
2. For a type of `console_json` or `file_json`: a formatter of `synapse.logging.JsonFormatter` should be used.
3. For a type of `console_json_terse` or `network_json_terse`: a formatter of `synapse.logging.TerseJsonFormatter` should be used.

For each new handler and formatter they should be added to the logging configuration and then assigned to either a logger or the root logger.

An example legacy configuration:

    structured: true

    loggers:
        synapse:
            level: INFO
        synapse.storage.SQL:
            level: WARNING

    drains:
        console:
            type: console
            location: stdout
        file:
            type: file_json
            location: homeserver.log

Would be converted into a new configuration:

    version: 1

    formatters:
        json:
            class: synapse.logging.JsonFormatter

    handlers:
        console:
            class: logging.StreamHandler
            location: ext://sys.stdout
        file:
            class: logging.FileHandler
            formatter: json
            filename: homeserver.log

    loggers:
        synapse:
            level: INFO
            handlers: [console, file]
        synapse.storage.SQL:
            level: WARNING

The new logging configuration is a bit more verbose, but significantly more flexible. It allows for configuration that were not previously possible, such as sending plain logs over the network, or using different handlers for different modules.

# Templates

Synapse uses parametrised templates to generate the content of emails it sends and webpages it shows to users.

By default, Synapse will use the templates listed here. Server admins can configure an additional directory for Synapse to look for templates in, allowing them to specify custom templates:

    templates:
      custom_templates_directory: /path/to/custom/templates/

If this setting is not set, or the files named below are not found within the directory, default templates from within the Synapse package will be used.

Templates that are given variables when being rendered are rendered using Jinja 2. Templates rendered by Jinja 2 can also access two functions on top of the functions already available as part of Jinja 2:

    format_ts(value: int, format: str) -> str

Formats a timestamp in milliseconds.

Example: `reason.last_sent_ts|format_ts("%c")`

    mxc_to_http(value: str, width: int, height: int, resize_method: str = "crop") -> str

Turns a `mxc://` URL for media content into an HTTP(S) one using the homeserver's `public_baseurl` configuration setting as the URL's base.

Example: `message.sender_avatar_url|mxc_to_http(32,32)`

## Email templates

Below are the templates Synapse will look for when generating the content of an email:

- `notif_mail.html` and `notif_mail.txt`: The contents of email notifications of missed events. When rendering, this template is given the following variables:
  - `user_display_name`: the display name for the user receiving the notification
  - `unsubscribe_link`: the link users can click to unsubscribe from email notifications
  - `summary_text`: a summary of the notification(s). The text used can be customised by configuring the various settings in the `email.subjects` section of the configuration file.
  - `rooms`: a list of rooms containing events to include in the email. Each element is an object with the following attributes:
    - `title`: a human-readable name for the room
    - `hash`: a hash of the ID of the room
    - `invite`: a boolean, which is `True` if the room is an invite the user hasn't accepted yet, `False` otherwise
    - `notifs`: a list of events, or an empty list if `invite` is `True`. Each element is an object with the following attributes:
      - `link`: a `matrix.to` link to the event
      - `ts`: the time in milliseconds at which the event was received
      - `messages`: a list of messages containing one message before the event, the message in the event, and one message after the event. Each element is an object with the following attributes:
        - `event_type`: the type of the event
        - `is_historical`: a boolean, which is `False` if the message is the one that triggered the notification, `True` otherwise
        - `id`: the ID of the event
        - `ts`: the time in milliseconds at which the event was sent
        - `sender_name`: the display name for the event's sender
        - `sender_avatar_url`: the avatar URL (as a `mxc://` URL) for the event's sender
        - `sender_hash`: a hash of the user ID of the sender
    - `link`: a `matrix.to` link to the room
  - `reason`: information on the event that triggered the email to be sent. It's an object with the following attributes:
    - `room_id`: the ID of the room the event was sent in
    - `room_name`: a human-readable name for the room the event was sent in
    - `now`: the current time in milliseconds
    - `received_at`: the time in milliseconds at which the event was received
    - `delay_before_mail_ms`: the amount of time in milliseconds Synapse always waits before ever emailing about a notification (to give the user a chance to respond to other push or notice the window)
    - `last_sent_ts`: the time in milliseconds at which a notification was last sent for an event in this room
    - `throttle_ms`: the minimum amount of time in milliseconds between two notifications can be sent for this room
- `password_reset.html` and `password_reset.txt`: The contents of password reset emails sent by the homeserver. When rendering, these templates are given a `link` variable which contains the link the user must click in order to reset their password.
- `registration.html` and `registration.txt`: The contents of address verification emails sent during registration. When rendering, these templates are given a `link` variable which contains the link the user must click in order to validate their email address.
- `add_threepid.html` and `add_threepid.txt`: The contents of address verification emails sent when an address is added to a Matrix account. When rendering, these templates are given a `link` variable which contains the link the user must click in order to validate their email address.

## HTML page templates for registration and password reset

Below are the templates Synapse will look for when generating pages related to registration and password reset:

- `password_reset_confirmation.html`: An HTML page that a user will see when they follow the link in the password reset email. The user will be asked to confirm the action before their password is reset. When rendering, this template is given the following variables:
  - `sid`: the session ID for the password reset
  - `token`: the token for the password reset
  - `client_secret`: the client secret for the password reset
- `password_reset_success.html` and `password_reset_failure.html`: HTML pages for success and failure that a user will see when they confirm the password reset flow using the page above. When rendering, `password_reset_success.html` is given no variable, and `password_reset_failure.html` is given a `failure_reason`, which contains the reason for the password reset failure.
- `registration_success.html` and `registration_failure.html`: HTML pages for success and failure that a user will see when they follow the link in an address verification email sent during registration. When rendering, `registration_success.html` is given no variable, and `registration_failure.html` is given a `failure_reason`, which contains the reason for the registration failure.
- `add_threepid_success.html` and `add_threepid_failure.html`: HTML pages for success and failure that a user will see when they follow the link in an address verification email sent when an address is added to a Matrix account. When rendering, `add_threepid_success.html` is given no variable, and `add_threepid_failure.html` is given a `failure_reason`, which contains the reason for the registration failure.

## HTML page templates for Single Sign-On (SSO)

Below are the templates Synapse will look for when generating pages related to SSO:

- `sso_login_idp_picker.html`: HTML page to prompt the user to choose an Identity Provider during login. This is only used if multiple SSO Identity Providers are configured. When rendering, this template is given the following variables:
  - `redirect_url`: the URL that the user will be redirected to after login.
  - `server_name`: the homeserver's name.
  - `providers`: a list of available Identity Providers. Each element is an object with the following attributes:
    - `idp_id`: unique identifier for the IdP
    - `idp_name`: user-facing name for the IdP
    - `idp_icon`: if specified in the IdP config, an MXC URI for an icon for the IdP
    - `idp_brand`: if specified in the IdP config, a textual identifier for the brand of the IdP The rendered HTML page should contain a form which submits its results back as a GET request, with the following query parameters:
  - `redirectUrl`: the client redirect URI (ie, the `redirect_url` passed to the template)
  - `idp`: the 'idp_id' of the chosen IDP.
- `sso_auth_account_details.html`: HTML page to prompt new users to enter a userid and confirm other details. This is only shown if the SSO implementation (with any `user_mapping_provider`) does not return a localpart. When rendering, this template is given the following variables:
  - `server_name`: the homeserver's name.
  - `idp`: details of the SSO Identity Provider that the user logged in with: an object with the following attributes:
    - `idp_id`: unique identifier for the IdP
    - `idp_name`: user-facing name for the IdP
    - `idp_icon`: if specified in the IdP config, an MXC URI for an icon for the IdP
    - `idp_brand`: if specified in the IdP config, a textual identifier for the brand of the IdP
  - `user_attributes`: an object containing details about the user that we received from the IdP. May have the following attributes:
    - display_name: the user's display_name
    - emails: a list of email addresses The template should render a form which submits the following fields:
  - `username`: the localpart of the user's chosen user id
- `sso_new_user_consent.html`: HTML page allowing the user to consent to the server's terms and conditions. This is only shown for new users, and only if `user_consent.require_at_registration` is set. When rendering, this template is given the following variables:
  - `server_name`: the homeserver's name.
  - `user_id`: the user's matrix proposed ID.
  - `user_profile.display_name`: the user's proposed display name, if any.
  - consent_version: the version of the terms that the user will be shown
  - `terms_url`: a link to the page showing the terms. The template should render a form which submits the following fields:
  - `accepted_version`: the version of the terms accepted by the user (ie, 'consent_version' from the input variables).
- `sso_redirect_confirm.html`: HTML page for a confirmation step before redirecting back to the client with the login token. When rendering, this template is given the following variables:
  - `redirect_url`: the URL the user is about to be redirected to.
  - `display_url`: the same as `redirect_url`, but with the query parameters stripped. The intention is to have a human-readable URL to show to users, not to use it as the final address to redirect to.
  - `server_name`: the homeserver's name.
  - `new_user`: a boolean indicating whether this is the user's first time logging in.
  - `user_id`: the user's matrix ID.
  - `user_profile.avatar_url`: an MXC URI for the user's avatar, if any. `None` if the user has not set an avatar.
  - `user_profile.display_name`: the user's display name. `None` if the user has not set a display name.
- `sso_auth_confirm.html`: HTML page which notifies the user that they are authenticating to confirm an operation on their account during the user interactive authentication process. When rendering, this template is given the following variables:
  - `redirect_url`: the URL the user is about to be redirected to.
  - `description`: the operation which the user is being asked to confirm
  - `idp`: details of the Identity Provider that we will use to confirm the user's identity: an object with the following attributes:
    - `idp_id`: unique identifier for the IdP
    - `idp_name`: user-facing name for the IdP
    - `idp_icon`: if specified in the IdP config, an MXC URI for an icon for the IdP
    - `idp_brand`: if specified in the IdP config, a textual identifier for the brand of the IdP
- `sso_auth_success.html`: HTML page shown after a successful user interactive authentication session. Note that this page must include the JavaScript which notifies of a successful authentication (see https://matrix.org/docs/spec/client_server/r0.6.0#fallback). This template has no additional variables.
- `sso_auth_bad_user.html`: HTML page shown after a user-interactive authentication session which does not map correctly onto the expected user. When rendering, this template is given the following variables:
  - `server_name`: the homeserver's name.
  - `user_id_to_verify`: the MXID of the user that we are trying to validate.
- `sso_account_deactivated.html`: HTML page shown during single sign-on if a deactivated user (according to Synapse's database) attempts to login. This template has no additional variables.
- `sso_error.html`: HTML page to display to users if something goes wrong during the OpenID Connect authentication process. When rendering, this template is given two variables:
  - `error`: the technical name of the error
  - `error_description`: a human-readable message for the error

# User Authentication

Synapse supports multiple methods of authenticating users, either out-of-the-box or through custom pluggable authentication modules.

Included in Synapse is support for authenticating users via:

- A username and password.
- An email address and password.
- Single Sign-On through the SAML, Open ID Connect or CAS protocols.
- JSON Web Tokens.
- An administrator's shared secret.

Synapse can additionally be extended to support custom authentication schemes through optional "password auth provider" modules.

# Configuring Synapse to authenticate against an OpenID Connect provider

Synapse can be configured to use an OpenID Connect Provider (OP) for authentication, instead of its own local password database.

Any OP should work with Synapse, as long as it supports the authorization code flow. There are a few options for that:

- start a local OP. Synapse has been tested with Hydra and Dex. Note that for an OP to work, it should be served under a secure (HTTPS) origin. A certificate signed with a self-signed, locally trusted CA should work. In that case, start Synapse with a `SSL_CERT_FILE` environment variable set to the path of the CA.

- set up a SaaS OP, like Google, Auth0 or Okta. Synapse has been tested with Auth0 and Google.

It may also be possible to use other OAuth2 providers which provide the authorization code grant type, such as Github.

## Preparing Synapse

The OpenID integration in Synapse uses the `authlib` library, which must be installed as follows:

- The relevant libraries are included in the Docker images and Debian packages provided by `matrix.org` so no further action is needed.

- If you installed Synapse into a virtualenv, run `/path/to/env/bin/pip install matrix-synapse[oidc]` to install the necessary dependencies.

- For other installation mechanisms, see the documentation provided by the maintainer.

To enable the OpenID integration, you should then add a section to the `oidc_providers` setting in your configuration file (or uncomment one of the existing examples). See sample_config.yaml for some sample settings, as well as the text below for example configurations for specific providers.

## Sample configs

Here are a few configs for providers that should work with Synapse.

### Microsoft Azure Active Directory

Azure AD can act as an OpenID Connect Provider. Register a new application under App registrations in the Azure AD management console. The RedirectURI for your application should point to your matrix server: `[synapse public baseurl]/_synapse/client/oidc/callback`

Go to Certificates & secrets and register a new client secret. Make note of your Directory (tenant) ID as it will be used in the Azure links. Edit your Synapse config file and change the `oidc_config` section:

    oidc_providers:
      - idp_id: microsoft
        idp_name: Microsoft
        issuer: "https://login.microsoftonline.com/<tenant id>/v2.0"
        client_id: "<client id>"
        client_secret: "<client secret>"
        scopes: ["openid", "profile"]
        authorization_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/authorize"
        token_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/token"
        userinfo_endpoint: "https://graph.microsoft.com/oidc/userinfo"

        user_mapping_provider:
          config:
            localpart_template: "{{ user.preferred_username.split('@')[0] }}"
            display_name_template: "{{ user.name }}"

### Dex

Dex is a simple, open-source, certified OpenID Connect Provider. Although it is designed to help building a full-blown provider with an external database, it can be configured with static passwords in a config file.

Follow the Getting Started guide to install Dex.

Edit `examples/config-dev.yaml` config file from the Dex repo to add a client:

    staticClients:
    - id: synapse
      secret: secret
      redirectURIs:
      - '[synapse public baseurl]/_synapse/client/oidc/callback'
      name: 'Synapse'

Run with `dex serve examples/config-dev.yaml`.

Synapse config:

    oidc_providers:
      - idp_id: dex
        idp_name: "My Dex server"
        skip_verification: true # This is needed as Dex is served on an insecure endpoint
        issuer: "http://127.0.0.1:5556/dex"
        client_id: "synapse"
        client_secret: "secret"
        scopes: ["openid", "profile"]
        user_mapping_provider:
          config:
            localpart_template: "{{ user.name }}"
            display_name_template: "{{ user.name|capitalize }}"

### Keycloak

Keycloak is an opensource IdP maintained by Red Hat.

Follow the Getting Started Guide to install Keycloak and set up a realm.

1. Click `Clients` in the sidebar and click `Create`

2. Fill in the fields as below:

Field | Value
--- | ---
Client ID | `synapse`
Client Protocol | `openid-connect`

3. Click `Save`
4. Fill in the fields as below:

Field | Value
--- | ---
Client ID | `synapse`
Enabled | `On`
Client Protocol | `openid-connect`
Access Type | `confidential`
Valid Redirect URIs | `[synapse public baseurl]/_synapse/client/oidc/callback`

5. Click `Save`
6. On the Credentials tab, update the fields:

Field | Value
--- | ---
Client Authenticator | `Client ID and Secret`

7. Click `Regenerate Secret`
8. Copy Secret

    oidc_providers:
      - idp_id: keycloak
        idp_name: "My KeyCloak server"
        issuer: "https://127.0.0.1:8443/auth/realms/{realm_name}"
        client_id: "synapse"
        client_secret: "copy secret generated from above"
        scopes: ["openid", "profile"]
        user_mapping_provider:
          config:
            localpart_template: "{{ user.preferred_username }}"
            display_name_template: "{{ user.name }}"

### Auth0

Auth0 is a hosted SaaS IdP solution.

1. Create a regular web application for Synapse

2. Set the Allowed Callback URLs to `[synapse public baseurl]/_synapse/client/oidc/callback`

3. Add a rule to add the `preferred_username` claim.

   Code sample

       function addPersistenceAttribute(user, context, callback) {
         user.user_metadata = user.user_metadata || {};
         user.user_metadata.preferred_username = user.user_metadata.preferred_username || user.user_id;
         context.idToken.preferred_username = user.user_metadata.preferred_username;

         auth0.users.updateUserMetadata(user.user_id, user.user_metadata)
           .then(function(){
               callback(null, user, context);
           })
           .catch(function(err){
               callback(err);
           });
       }

Synapse config:

    oidc_providers:
      - idp_id: auth0
        idp_name: Auth0
        issuer: "https://your-tier.eu.auth0.com/" # TO BE FILLED
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        scopes: ["openid", "profile"]
        user_mapping_provider:
          config:
            localpart_template: "{{ user.preferred_username }}"
            display_name_template: "{{ user.name }}"

### GitHub

GitHub is a bit special as it is not an OpenID Connect compliant provider, but just a regular OAuth2 provider.

The `/user` API endpoint can be used to retrieve information on the authenticated user. As the Synapse login mechanism needs an attribute to uniquely identify users, and that endpoint does not return a `sub` property, an alternative `subject_claim` has to be set.

1. Create a new OAuth application: https://github.com/settings/applications/new.
2. Set the callback URL to `[synapse public baseurl]/_synapse/client/oidc/callback`.

Synapse config:

    oidc_providers:
      - idp_id: github
        idp_name: Github
        idp_brand: "github"  # optional: styling hint for clients
        discover: false
        issuer: "https://github.com/"
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        authorization_endpoint: "https://github.com/login/oauth/authorize"
        token_endpoint: "https://github.com/login/oauth/access_token"
        userinfo_endpoint: "https://api.github.com/user"
        scopes: ["read:user"]
        user_mapping_provider:
          config:
            subject_claim: "id"
            localpart_template: "{{ user.login }}"
            display_name_template: "{{ user.name }}"

### Google

Google is an OpenID certified authentication and authorisation provider.

1. Set up a project in the Google API Console (see https://developers.google.com/identity/protocols/oauth2/openid-connect#appsetup).
2. Add an "OAuth Client ID" for a Web Application under "Credentials".
3. Copy the Client ID and Client Secret, and add the following to your synapse config:

       oidc_providers:
         - idp_id: google
           idp_name: Google
           idp_brand: "google"  # optional: styling hint for clients
           issuer: "https://accounts.google.com/"
           client_id: "your-client-id" # TO BE FILLED
           client_secret: "your-client-secret" # TO BE FILLED
           scopes: ["openid", "profile"]
           user_mapping_provider:
             config:
               localpart_template: "{{ user.given_name|lower }}"
               display_name_template: "{{ user.name }}"

4. Back in the Google console, add this Authorized redirect URI: `[synapse public baseurl]/_synapse/client/oidc/callback`.

### Twitch

1. Setup a developer account on Twitch
2. Obtain the OAuth 2.0 credentials by creating an app
3. Add this OAuth Redirect URL: `[synapse public baseurl]/_synapse/client/oidc/callback`

Synapse config:

    oidc_providers:
      - idp_id: twitch
        idp_name: Twitch
        issuer: "https://id.twitch.tv/oauth2/"
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        client_auth_method: "client_secret_post"
        user_mapping_provider:
          config:
            localpart_template: "{{ user.preferred_username }}"
            display_name_template: "{{ user.name }}"

### GitLab

1. Create a new application.
2. Add the `read_user` and `openid` scopes.
3. Add this Callback URL: `[synapse public baseurl]/_synapse/client/oidc/callback`

Synapse config:

    oidc_providers:
      - idp_id: gitlab
        idp_name: Gitlab
        idp_brand: "gitlab"  # optional: styling hint for clients
        issuer: "https://gitlab.com/"
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        client_auth_method: "client_secret_post"
        scopes: ["openid", "read_user"]
        user_profile_method: "userinfo_endpoint"
        user_mapping_provider:
          config:
            localpart_template: '{{ user.nickname }}'
            display_name_template: '{{ user.name }}'

### Facebook

Like Github, Facebook provide a custom OAuth2 API rather than an OIDC-compliant one so requires a little more configuration.

0. You will need a Facebook developer account. You can register for one here.
1. On the apps page of the developer console, "Create App", and choose "Build Connected Experiences".
2. Once the app is created, add "Facebook Login" and choose "Web". You don't need to go through the whole form here.
3. In the left-hand menu, open "Products"/"Facebook Login"/"Settings".
   - Add `[synapse public baseurl]/_synapse/client/oidc/callback` as an OAuth Redirect URL.
4. In the left-hand menu, open "Settings/Basic". Here you can copy the "App ID" and "App Secret" for use below.

Synapse config:

      - idp_id: facebook
        idp_name: Facebook
        idp_brand: "facebook"  # optional: styling hint for clients
        discover: false
        issuer: "https://facebook.com"
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        scopes: ["openid", "email"]
        authorization_endpoint: https://facebook.com/dialog/oauth
        token_endpoint: https://graph.facebook.com/v9.0/oauth/access_token
        user_profile_method: "userinfo_endpoint"
        userinfo_endpoint: "https://graph.facebook.com/v9.0/me?fields=id,name,email,picture"
        user_mapping_provider:
          config:
            subject_claim: "id"
            display_name_template: "{{ user.name }}"

Relevant documents:

- https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow
- Using Facebook's Graph API: https://developers.facebook.com/docs/graph-api/using-graph-api/
- Reference to the User endpoint: https://developers.facebook.com/docs/graph-api/reference/user

### Gitea

Gitea is, like Github, not an OpenID provider, but just an OAuth2 provider.

The `/user` API endpoint can be used to retrieve information on the authenticated user. As the Synapse login mechanism needs an attribute to uniquely identify users, and that endpoint does not return a `sub` property, an alternative `subject_claim` has to be set.

1. Create a new application.
2. Add this Callback URL: `[synapse public baseurl]/_synapse/client/oidc/callback`

Synapse config:

    oidc_providers:
      - idp_id: gitea
        idp_name: Gitea
        discover: false
        issuer: "https://your-gitea.com/"
        client_id: "your-client-id" # TO BE FILLED
        client_secret: "your-client-secret" # TO BE FILLED
        client_auth_method: client_secret_post
        scopes: [] # Gitea doesn't support Scopes
        authorization_endpoint: "https://your-gitea.com/login/oauth/authorize"
        token_endpoint: "https://your-gitea.com/login/oauth/access_token"
        userinfo_endpoint: "https://your-gitea.com/api/v1/user"
        user_mapping_provider:
          config:
            subject_claim: "id"
            localpart_template: "{{ user.login }}"
            display_name_template: "{{ user.full_name }}"

### XWiki

Install OpenID Connect Provider extension in your XWiki instance.

Synapse config:

    oidc_providers:
      - idp_id: xwiki
        idp_name: "XWiki"
        issuer: "https://myxwikihost/xwiki/oidc/"
        client_id: "your-client-id" # TO BE FILLED
        client_auth_method: none
        scopes: ["openid", "profile"]
        user_profile_method: "userinfo_endpoint"
        user_mapping_provider:
          config:
            localpart_template: "{{ user.preferred_username }}"
            display_name_template: "{{ user.name }}"

### Apple

Configuring "Sign in with Apple" (SiWA) requires an Apple Developer account.

You will need to create a new "Services ID" for SiWA, and create and download a private key with "SiWA" enabled.

As well as the private key file, you will need:

- Client ID: the "identifier" you gave the "Services ID"
- Team ID: a 10-character ID associated with your developer account.
- Key ID: the 10-character identifier for the key.

https://help.apple.com/developer-account/?lang=en#/dev77c875b7e has more documentation on setting up SiWA.

The synapse config will look like this:

      - idp_id: apple
        idp_name: Apple
        issuer: "https://appleid.apple.com"
        client_id: "your-client-id" # Set to the "identifier" for your "ServicesID"
        client_auth_method: "client_secret_post"
        client_secret_jwt_key:
          key_file: "/path/to/AuthKey_KEYIDCODE.p8"  # point to your key file
          jwt_header:
            alg: ES256
            kid: "KEYIDCODE"   # Set to the 10-char Key ID
          jwt_payload:
            iss: TEAMIDCODE    # Set to the 10-char Team ID
        scopes: ["name", "email", "openid"]
        authorization_endpoint: https://appleid.apple.com/auth/authorize?response_mode=form_post
        user_mapping_provider:
          config:
            email_template: "{{ user.email }}"

## Django OAuth Toolkit

django-oauth-toolkit is a Django application providing out of the box all the endpoints, data and logic needed to add OAuth2 capabilities to your Django projects. It supports OpenID Connect too.

Configuration on Django's side:

1. Add an application: https://example.com/admin/oauth2_provider/application/add/ and choose parameters like this:

- `Redirect uris`: https://synapse.example.com/_synapse/client/oidc/callback
- `Client type`: `Confidential`
- `Authorization grant type`: `Authorization code`
- `Algorithm`: `HMAC with SHA-2 256`

2. You can customize the claims Django gives to synapse (optional):

   Code sample

       class CustomOAuth2Validator(OAuth2Validator):

           def get_additional_claims(self, request):
               return {
                   "sub": request.user.email,
                   "email": request.user.email,
                   "first_name": request.user.first_name,
                   "last_name": request.user.last_name,
               }

Your synapse config is then:

    oidc_providers:
      - idp_id: django_example
        idp_name: "Django Example"
        issuer: "https://example.com/o/"
        client_id: "your-client-id"  # CHANGE ME
        client_secret: "your-client-secret"  # CHANGE ME
        scopes: ["openid"]
        user_profile_method: "userinfo_endpoint"  # needed because oauth-toolkit does not include user information in the authorization response
        user_mapping_provider:
          config:
            localpart_template: "{{ user.email.split('@')[0] }}"
            display_name_template: "{{ user.first_name }} {{ user.last_name }}"
            email_template: "{{ user.email }}"

# SSO Mapping Providers

A mapping provider is a Python class (loaded via a Python module) that works out how to map attributes of a SSO response to Matrix-specific user attributes. Details such as user ID localpart, displayname, and even avatar URLs are all things that can be mapped from talking to a SSO service.

As an example, a SSO service may return the email address "john.smith@example.com" for a user, whereas Synapse will need to figure out how to turn that into a displayname when creating a Matrix user for this individual. It may choose `John Smith`, or `Smith, John [Example.com]` or any number of variations. As each Synapse configuration may want something different, this is where SAML mapping providers come into play.

SSO mapping providers are currently supported for OpenID and SAML SSO configurations. Please see the details below for how to implement your own.

It is up to the mapping provider whether the user should be assigned a predefined Matrix ID based on the SSO attributes, or if the user should be allowed to choose their own username.

In the first case - where users are automatically allocated a Matrix ID - it is the responsibility of the mapping provider to normalise the SSO attributes and map them to a valid Matrix ID. The specification for Matrix IDs has some information about what is considered valid.

If the mapping provider does not assign a Matrix ID, then Synapse will automatically serve an HTML page allowing the user to pick their own username.

External mapping providers are provided to Synapse in the form of an external Python module. You can retrieve this module from PyPI or elsewhere, but it must be importable via Synapse (e.g. it must be in the same virtualenv as Synapse). The Synapse config is then modified to point to the mapping provider (and optionally provide additional configuration for it).

## OpenID Mapping Providers

The OpenID mapping provider can be customized by editing the `oidc_config.user_mapping_provider.module` config option.

`oidc_config.user_mapping_provider.config` allows you to provide custom configuration options to the module. Check with the module's documentation for what options it provides (if any). The options listed by default are for the user mapping provider built in to Synapse. If using a custom module, you should comment these options out and use those specified by the module instead.

### Building a Custom OpenID Mapping Provider

A custom mapping provider must specify the following methods:

- `__init__(self, parsed_config)`
  - Arguments:
    - `parsed_config` - A configuration object that is the return value of the `parse_config` method. You should set any configuration options needed by the module here.
- `parse_config(config)`
  - This method should have the `@staticmethod` decoration.
  - Arguments:
    - `config` - A `dict` representing the parsed content of the `oidc_config.user_mapping_provider.config` homeserver config option. Runs on homeserver startup. Providers should extract and validate any option values they need here.
  - Whatever is returned will be passed back to the user mapping provider module's `__init__` method during construction.
- `get_remote_user_id(self, userinfo)`
  - Arguments:
    - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user information from.
  - This method must return a string, which is the unique, immutable identifier for the user. Commonly the `sub` claim of the response.
- `map_user_attributes(self, userinfo, token, failures)`
  - This method must be async.
  - Arguments:
    - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user information from.
    - `token` - A dictionary which includes information necessary to make further requests to the OpenID provider.
    - `failures` - An `int` that represents the amount of times the returned mxid localpart mapping has failed. This should be used to create a deduplicated mxid localpart which should be returned instead. For example, if this method returns `john.doe` as the value of `localpart` in the returned dict, and that is already taken on the homeserver, this method will be called again with the same parameters but with failures=1. The method should then return a different `localpart` value, such as `john.doe1`.
  - Returns a dictionary with two keys:
    - `localpart`: A string, used to generate the Matrix ID. If this is `None`, the user is prompted to pick their own username. This is only used during a user's first login. Once a localpart has been associated with a remote user ID (see `get_remote_user_id`) it cannot be updated.
    - `displayname`: An optional string, the display name for the user.
- `get_extra_attributes(self, userinfo, token)`

  - This method must be async.

  - Arguments:

    - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user information from.
    - `token` - A dictionary which includes information necessary to make further requests to the OpenID provider.

  - Returns a dictionary that is suitable to be serialized to JSON. This will be returned as part of the response during a successful login.

    Note that care should be taken to not overwrite any of the parameters usually returned as part of the login response.

### Default OpenID Mapping Provider

Synapse has a built-in OpenID mapping provider if a custom provider isn't specified in the config. It is located at `synapse.handlers.oidc.JinjaOidcMappingProvider`.

## SAML Mapping Providers

The SAML mapping provider can be customized by editing the `saml2_config.user_mapping_provider.module` config option.

`saml2_config.user_mapping_provider.config` allows you to provide custom configuration options to the module. Check with the module's documentation for what options it provides (if any). The options listed by default are for the user mapping provider built in to Synapse. If using a custom module, you should comment these options out and use those specified by the module instead.

### Building a Custom SAML Mapping Provider

A custom mapping provider must specify the following methods:

- `__init__(self, parsed_config, module_api)`
  - Arguments:
    - `parsed_config` - A configuration object that is the return value of the `parse_config` method. You should set any configuration options needed by the module here.
    - `module_api` - a `synapse.module_api.ModuleApi` object which provides the stable API available for extension modules.
- `parse_config(config)`
  - This method should have the `@staticmethod` decoration.
  - Arguments:
    - `config` - A `dict` representing the parsed content of the `saml_config.user_mapping_provider.config` homeserver config option. Runs on homeserver startup. Providers should extract and validate any option values they need here.
  - Whatever is returned will be passed back to the user mapping provider module's `__init__` method during construction.
- `get_saml_attributes(config)`
  - This method should have the `@staticmethod` decoration.
  - Arguments:
    - `config` - A object resulting from a call to `parse_config`.
  - Returns a tuple of two sets. The first set equates to the SAML auth response attributes that are required for the module to function, whereas the second set consists of those attributes which can be used if available, but are not necessary.
- `get_remote_user_id(self, saml_response, client_redirect_url)`
  - Arguments:
    - `saml_response` - A `saml2.response.AuthnResponse` object to extract user information from.
    - `client_redirect_url` - A string, the URL that the client will be redirected to.
  - This method must return a string, which is the unique, immutable identifier for the user. Commonly the `uid` claim of the response.
- `saml_response_to_user_attributes(self, saml_response, failures, client_redirect_url)`

  - Arguments:

    - `saml_response` - A `saml2.response.AuthnResponse` object to extract user information from.
    - `failures` - An `int` that represents the amount of times the returned mxid localpart mapping has failed. This should be used to create a deduplicated mxid localpart which should be returned instead. For example, if this method returns `john.doe` as the value of `mxid_localpart` in the returned dict, and that is already taken on the homeserver, this method will be called again with the same parameters but with failures=1. The method should then return a different `mxid_localpart` value, such as `john.doe1`.
    - `client_redirect_url` - A string, the URL that the client will be redirected to.

  - This method must return a dictionary, which will then be used by Synapse to build a new user. The following keys are allowed:

    - `mxid_localpart` - A string, the mxid localpart of the new user. If this is `None`, the user is prompted to pick their own username. This is only used during a user's first login. Once a localpart has been associated with a remote user ID (see `get_remote_user_id`) it cannot be updated.
    - `displayname` - The displayname of the new user. If not provided, will default to the value of `mxid_localpart`.
    - `emails` - A list of emails for the new user. If not provided, will default to an empty list.

    Alternatively it can raise a `synapse.api.errors.RedirectException` to redirect the user to another page. This is useful to prompt the user for additional information, e.g. if you want them to provide their own username. It is the responsibility of the mapping provider to either redirect back to `client_redirect_url` (including any additional information) or to complete registration using methods from the `ModuleApi`.

### Default SAML Mapping Provider

Synapse has a built-in SAML mapping provider if a custom provider isn't specified in the config. It is located at `synapse.handlers.saml.DefaultSamlMappingProvider`.

## This page of the Synapse documentation is now deprecated. For up to date documentation on setting up or writing a password auth provider module, please see this page.

# Password auth provider modules

Password auth providers offer a way for server administrators to integrate their Synapse installation with an existing authentication system.

A password auth provider is a Python class which is dynamically loaded into Synapse, and provides a number of methods by which it can integrate with the authentication system.

This document serves as a reference for those looking to implement their own password auth providers. Additionally, here is a list of known password auth provider module implementations:

- matrix-synapse-ldap3
- matrix-synapse-shared-secret-auth
- matrix-synapse-rest-password-provider

## Required methods

Password auth provider classes must provide the following methods:

- `parse_config(config)` This method is passed the `config` object for this module from the homeserver configuration file.

  It should perform any appropriate sanity checks on the provided configuration, and return an object which is then passed into `__init__`.

  This method should have the `@staticmethod` decoration.

- `__init__(self, config, account_handler)`

  The constructor is passed the config object returned by `parse_config`, and a `synapse.module_api.ModuleApi` object which allows the password provider to check if accounts exist and/or create new ones.

## Optional methods

Password auth provider classes may optionally provide the following methods:

- `get_db_schema_files(self)`

  This method, if implemented, should return an Iterable of `(name, stream)` pairs of database schema files. Each file is applied in turn at initialisation, and a record is then made in the database so that it is not re-applied on the next start.

- `get_supported_login_types(self)`

  This method, if implemented, should return a `dict` mapping from a login type identifier (such as `m.login.password`) to an iterable giving the fields which must be provided by the user in the submission to the `/login` API. These fields are passed in the `login_dict` dictionary to `check_auth`.

  For example, if a password auth provider wants to implement a custom login type of `com.example.custom_login`, where the client is expected to pass the fields `secret1` and `secret2`, the provider should implement this method and return the following dict:

      {"com.example.custom_login": ("secret1", "secret2")}

- `check_auth(self, username, login_type, login_dict)`

  This method does the real work. If implemented, it will be called for each login attempt where the login type matches one of the keys returned by `get_supported_login_types`.

  It is passed the (possibly unqualified) `user` field provided by the client, the login type, and a dictionary of login secrets passed by the client.

  The method should return an `Awaitable` object, which resolves to the canonical `@localpart:domain` user ID if authentication is successful, and `None` if not.

  Alternatively, the `Awaitable` can resolve to a `(str, func)` tuple, in which case the second field is a callback which will be called with the result from the `/login` call (including `access_token`, `device_id`, etc.)

- `check_3pid_auth(self, medium, address, password)`

  This method, if implemented, is called when a user attempts to register or log in with a third party identifier, such as email. It is passed the medium (ex. "email"), an address (ex. "jdoe@example.com") and the user's password.

  The method should return an `Awaitable` object, which resolves to a `str` containing the user's (canonical) User id if authentication was successful, and `None` if not.

  As with `check_auth`, the `Awaitable` may alternatively resolve to a `(user_id, callback)` tuple.

- `check_password(self, user_id, password)`

  This method provides a simpler interface than `get_supported_login_types` and `check_auth` for password auth providers that just want to provide a mechanism for validating `m.login.password` logins.

  If implemented, it will be called to check logins with an `m.login.password` login type. It is passed a qualified `@localpart:domain` user id, and the password provided by the user.

  The method should return an `Awaitable` object, which resolves to `True` if authentication is successful, and `False` if not.

- `on_logged_out(self, user_id, device_id, access_token)`

  This method, if implemented, is called when a user logs out. It is passed the qualified user ID, the ID of the deactivated device (if any: access tokens are occasionally created without an associated device ID), and the (now deactivated) access token.

  It may return an `Awaitable` object; the logout request will wait for the `Awaitable` to complete, but the result is ignored.

# JWT Login Type

Synapse comes with a non-standard login type to support JSON Web Tokens. In general the documentation for the login endpoint is still valid (and the mechanism works similarly to the token based login).

To log in using a JSON Web Token, clients should submit a `/login` request as follows:

    {
      "type": "org.matrix.login.jwt",
      "token": "<jwt>"
    }

Note that the login type of `m.login.jwt` is supported, but is deprecated. This will be removed in a future version of Synapse.

The `token` field should include the JSON web token with the following claims:

- The `sub` (subject) claim is required and should encode the local part of the user ID.
- The expiration time (`exp`), not before time (`nbf`), and issued at (`iat`) claims are optional, but validated if present.
- The issuer (`iss`) claim is optional, but required and validated if configured.
- The audience (`aud`) claim is optional, but required and validated if configured. Providing the audience claim when not configured will cause validation to fail.

In the case that the token is not valid, the homeserver must respond with `403 Forbidden` and an error code of `M_FORBIDDEN`.

As with other login types, there are additional fields (e.g. `device_id` and `initial_device_display_name`) which can be included in the above request.

## Preparing Synapse

The JSON Web Token integration in Synapse uses the `PyJWT` library, which must be installed as follows:

- The relevant libraries are included in the Docker images and Debian packages provided by `matrix.org` so no further action is needed.

- If you installed Synapse into a virtualenv, run `/path/to/env/bin/pip install synapse[pyjwt]` to install the necessary dependencies.

- For other installation mechanisms, see the documentation provided by the maintainer.

To enable the JSON web token integration, you should then add an `jwt_config` section to your configuration file (or uncomment the `enabled: true` line in the existing section). See sample_config.yaml for some sample settings.

## How to test JWT as a developer

Although JSON Web Tokens are typically generated from an external server, the examples below use PyJWT directly.

1. Configure Synapse with JWT logins, note that this example uses a pre-shared secret and an algorithm of HS256:

       jwt_config:
           enabled: true
           secret: "my-secret-token"
           algorithm: "HS256"

2. Generate a JSON web token:

       $ pyjwt --key=my-secret-token --alg=HS256 encode sub=test-user
       eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ0ZXN0LXVzZXIifQ.Ag71GT8v01UO3w80aqRPTeuVPBIBZkYhNTJJ-_-zQIc

3. Query for the login types and ensure `org.matrix.login.jwt` is there:

       curl http://localhost:8080/_matrix/client/r0/login

4. Login used the generated JSON web token from above:

       $ curl http://localhost:8082/_matrix/client/r0/login -X POST \
           --data '{"type":"org.matrix.login.jwt","token":"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ0ZXN0LXVzZXIifQ.Ag71GT8v01UO3w80aqRPTeuVPBIBZkYhNTJJ-_-zQIc"}'
       {
           "access_token": "<access token>",
           "device_id": "ACBDEFGHI",
           "home_server": "localhost:8080",
           "user_id": "@test-user:localhost:8480"
       }

You should now be able to use the returned access token to query the client API.

# Overview

A captcha can be enabled on your homeserver to help prevent bots from registering accounts. Synapse currently uses Google's reCAPTCHA service which requires API keys from Google.

## Getting API keys

1. Create a new site at https://www.google.com/recaptcha/admin/create
2. Set the label to anything you want
3. Set the type to reCAPTCHA v2 using the "I'm not a robot" Checkbox option. This is the only type of captcha that works with Synapse.
4. Add the public hostname for your server, as set in `public_baseurl` in `homeserver.yaml`, to the list of authorized domains. If you have not set `public_baseurl`, use `server_name`.
5. Agree to the terms of service and submit.
6. Copy your site key and secret key and add them to your `homeserver.yaml` configuration file

       recaptcha_public_key: YOUR_SITE_KEY
       recaptcha_private_key: YOUR_SECRET_KEY

7. Enable the CAPTCHA for new registrations

       enable_registration_captcha: true

8. Go to the settings page for the CAPTCHA you just created
9. Uncheck the "Verify the origin of reCAPTCHA solutions" checkbox so that the captcha can be displayed in any client. If you do not disable this option then you must specify the domains of every client that is allowed to display the CAPTCHA.

## Configuring IP used for auth

The reCAPTCHA API requires that the IP address of the user who solved the CAPTCHA is sent. If the client is connecting through a proxy or load balancer, it may be required to use the `X-Forwarded-For` (XFF) header instead of the origin IP address. This can be configured using the `x_forwarded` directive in the listeners section of the `homeserver.yaml` configuration file.

# Registering an Application Service

The registration of new application services depends on the homeserver used. In synapse, you need to create a new configuration file for your AS and add it to the list specified under the `app_service_config_files` config option in your synapse config.

For example:

    app_service_config_files:
    - /home/matrix/.synapse/<your-AS>.yaml

The format of the AS configuration file is as follows:

    url: <base url of AS>
    as_token: <token AS will add to requests to HS>
    hs_token: <token HS will add to requests to AS>
    sender_localpart: <localpart of AS user>
    namespaces:
      users:  # List of users we're interested in
        - exclusive: <bool>
          regex: <regex>
          group_id: <group>
        - ...
      aliases: []  # List of aliases we're interested in
      rooms: [] # List of room ids we're interested in

`exclusive`: If enabled, only this application service is allowed to register users in its namespace(s). `group_id`: All users of this application service are dynamically joined to this group. This is useful for e.g user organisation or flairs.

See the spec for further details on how application services work.

# Server Notices

'Server Notices' are a new feature introduced in Synapse 0.30. They provide a channel whereby server administrators can send messages to users on the server.

They are used as part of communication of the server polices (see Consent Tracking), however the intention is that they may also find a use for features such as "Message of the day".

This is a feature specific to Synapse, but it uses standard Matrix communication mechanisms, so should work with any Matrix client.

## User experience

When the user is first sent a server notice, they will get an invitation to a room (typically called 'Server Notices', though this is configurable in `homeserver.yaml`). They will be unable to reject this invitation - attempts to do so will receive an error.

Once they accept the invitation, they will see the notice message in the room history; it will appear to have come from the 'server notices user' (see below).

The user is prevented from sending any messages in this room by the power levels.

Having joined the room, the user can leave the room if they want. Subsequent server notices will then cause a new room to be created.

## Synapse configuration

Server notices come from a specific user id on the server. Server administrators are free to choose the user id - something like `server` is suggested, meaning the notices will come from `@server:<your_server_name>`. Once the Server Notices user is configured, that user id becomes a special, privileged user, so administrators should ensure that it is not already allocated.

In order to support server notices, it is necessary to add some configuration to the `homeserver.yaml` file. In particular, you should add a `server_notices` section, which should look like this:

    server_notices:
       system_mxid_localpart: server
       system_mxid_display_name: "Server Notices"
       system_mxid_avatar_url: "mxc://server.com/oumMVlgDnLYFaPVkExemNVVZ"
       room_name: "Server Notices"

The only compulsory setting is `system_mxid_localpart`, which defines the user id of the Server Notices user, as above. `room_name` defines the name of the room which will be created.

`system_mxid_display_name` and `system_mxid_avatar_url` can be used to set the displayname and avatar of the Server Notices user.

## Sending notices

To send server notices to users you can use the admin_api.

# Support in Synapse for tracking agreement to server terms and conditions

Synapse 0.30 introduces support for tracking whether users have agreed to the terms and conditions set by the administrator of a server - and blocking access to the server until they have.

There are several parts to this functionality; each requires some specific configuration in `homeserver.yaml` to be enabled.

Note that various parts of the configuation and this document refer to the "privacy policy": agreement with a privacy policy is one particular use of this feature, but of course adminstrators can specify other terms and conditions unrelated to "privacy" per se.

## Collecting policy agreement from a user

Synapse can be configured to serve the user a simple policy form with an "accept" button. Clicking "Accept" records the user's acceptance in the database and shows a success page.

To enable this, first create templates for the policy and success pages. These should be stored on the local filesystem.

These templates use the Jinja2 templating language, and docs/privacy_policy_templates gives examples of the sort of thing that can be done.

Note that the templates must be stored under a name giving the language of the template - currently this must always be `en` (for "English"); internationalisation support is intended for the future.

The template for the policy itself should be versioned and named according to the version: for example `1.0.html`. The version of the policy which the user has agreed to is stored in the database.

Once the templates are in place, make the following changes to `homeserver.yaml`:

1. Add a `user_consent` section, which should look like:

       user_consent:
         template_dir: privacy_policy_templates
         version: 1.0

   `template_dir` points to the directory containing the policy templates. `version` defines the version of the policy which will be served to the user. In the example above, Synapse will serve `privacy_policy_templates/en/1.0.html`.

2. Add a `form_secret` setting at the top level:

       form_secret: "<unique secret>"

   This should be set to an arbitrary secret string (try `pwgen -y 30` to generate suitable secrets).

   More on what this is used for below.

3. Add `consent` wherever the `client` resource is currently enabled in the `listeners` configuration. For example:

       listeners:
         - port: 8008
           resources:
             - names:
               - client
               - consent

Finally, ensure that `jinja2` is installed. If you are using a virtualenv, this should be a matter of `pip install Jinja2`. On debian, try `apt-get install python-jinja2`.

Once this is complete, and the server has been restarted, try visiting `https://<server>/_matrix/consent`. If correctly configured, this should give an error "Missing string query parameter 'u'". It is now possible to manually construct URIs where users can give their consent.

### Enabling consent tracking at registration

1. Add the following to your configuration:

       user_consent:
         require_at_registration: true
         policy_name: "Privacy Policy" # or whatever you'd like to call the policy

2. In your consent templates, make use of the `public_version` variable to see if an unauthenticated user is viewing the page. This is typically wrapped around the form that would be used to actually agree to the document:

       {% if not public_version %}
         <!-- The variables used here are only provided when the 'u' param is given to the homeserver -->
         <form method="post" action="consent">
           <input type="hidden" name="v" value="{{version}}"/>
           <input type="hidden" name="u" value="{{user}}"/>
           <input type="hidden" name="h" value="{{userhmac}}"/>
           <input type="submit" value="Sure thing!"/>
         </form>
       {% endif %}

3. Restart Synapse to apply the changes.

Visiting `https://<server>/_matrix/consent` should now give you a view of the privacy document. This is what users will be able to see when registering for accounts.

### Constructing the consent URI

It may be useful to manually construct the "consent URI" for a given user - for instance, in order to send them an email asking them to consent. To do this, take the base `https://<server>/_matrix/consent` URL and add the following query parameters:

- `u`: the user id of the user. This can either be a full MXID (`@user:server.com`) or just the localpart (`user`).

- `h`: hex-encoded HMAC-SHA256 of `u` using the `form_secret` as a key. It is possible to calculate this on the commandline with something like:

      echo -n '<user>' | openssl sha256 -hmac '<form_secret>'

  This should result in a URI which looks something like: `https://<server>/_matrix/consent?u=<user>&h=68a152465a4d...`.

Note that not providing a `u` parameter will be interpreted as wanting to view the document from an unauthenticated perspective, such as prior to registration. Therefore, the `h` parameter is not required in this scenario. To enable this behaviour, set `require_at_registration` to `true` in your `user_consent` config.

## Sending users a server notice asking them to agree to the policy

It is possible to configure Synapse to send a server notice to anybody who has not yet agreed to the current version of the policy. To do so:

- ensure that the consent resource is configured, as in the previous section

- ensure that server notices are configured, as in the server notice documentation.

- Add `server_notice_content` under `user_consent` in `homeserver.yaml`. For example:

      user_consent:
        server_notice_content:
          msgtype: m.text
          body: >-
            Please give your consent to the privacy policy at %(consent_uri)s.

  Synapse automatically replaces the placeholder `%(consent_uri)s` with the consent uri for that user.

- ensure that `public_baseurl` is set in `homeserver.yaml`, and gives the base URI that clients use to connect to the server. (It is used to construct `consent_uri` in the server notice.)

## Blocking users from using the server until they agree to the policy

Synapse can be configured to block any attempts to join rooms or send messages until the user has given their agreement to the policy. (Joining the server notices room is exempted from this).

To enable this, add `block_events_error` under `user_consent`. For example:

    user_consent:
      block_events_error: >-
        You can't send any messages until you consent to the privacy policy at
        %(consent_uri)s.

Synapse automatically replaces the placeholder `%(consent_uri)s` with the consent uri for that user.

ensure that `public_baseurl` is set in `homeserver.yaml`, and gives the base URI that clients use to connect to the server. (It is used to construct `consent_uri` in the error.)

# URL Previews

The `GET /_matrix/media/r0/preview_url` endpoint provides a generic preview API for URLs which outputs Open Graph responses (with some Matrix specific additions).

This does have trade-offs compared to other designs:

- Pros:
  - Simple and flexible; can be used by any clients at any point
- Cons:
  - If each homeserver provides one of these independently, all the HSes in a room may needlessly DoS the target URI
  - The URL metadata must be stored somewhere, rather than just using Matrix itself to store the media.
  - Matrix cannot be used to distribute the metadata between homeservers.

When Synapse is asked to preview a URL it does the following:

1. Checks against a URL blacklist (defined as `url_preview_url_blacklist` in the config).
2. Checks the in-memory cache by URLs and returns the result if it exists. (This is also used to de-duplicate processing of multiple in-flight requests at once.)
3. Kicks off a background process to generate a preview:
   1. Checks the database cache by URL and timestamp and returns the result if it has not expired and was successful (a 2xx return code).
   2. Checks if the URL matches an oEmbed pattern. If it does, update the URL to download.
   3. Downloads the URL and stores it into a file via the media storage provider and saves the local media metadata.
   4. If the media is an image:
      1. Generates thumbnails.
      2. Generates an Open Graph response based on image properties.
   5. If the media is HTML:
      1. Decodes the HTML via the stored file.
      2. Generates an Open Graph response from the HTML.
      3. If an image exists in the Open Graph response:
         1. Downloads the URL and stores it into a file via the media storage provider and saves the local media metadata.
         2. Generates thumbnails.
         3. Updates the Open Graph response based on image properties.
   6. If the media is JSON and an oEmbed URL was found:
      1. Convert the oEmbed response to an Open Graph response.
      2. If a thumbnail or image is in the oEmbed response:
         1. Downloads the URL and stores it into a file via the media storage provider and saves the local media metadata.
         2. Generates thumbnails.
         3. Updates the Open Graph response based on image properties.
   7. Stores the result in the database cache.
4. Returns the result.

The in-memory cache expires after 1 hour.

Expired entries in the database cache (and their associated media files) are deleted every 10 seconds. The default expiration time is 1 hour from download.

# User Directory API Implementation

The user directory is currently maintained based on the 'visible' users on this particular server - i.e. ones which your account shares a room with, or who are present in a publicly viewable room present on the server.

The directory info is stored in various tables, which can (typically after DB corruption) get stale or out of sync. If this happens, for now the solution to fix it is to execute the SQL here and then restart synapse. This should then start a background task to flush the current tables and regenerate the directory.

## Data model

There are five relevant tables that collectively form the "user directory". Three of them track a master list of all the users we could search for. The last two (collectively called the "search tables") track who can see who.

From all of these tables we exclude three types of local user:

- support users
- appservice users
- deactivated users

- `user_directory`. This contains the user_id, display name and avatar we'll return when you search the directory.

  - Because there's only one directory entry per user, it's important that we only ever put publicly visible names here. Otherwise we might leak a private nickname or avatar used in a private room.
  - Indexed on rooms. Indexed on users.

- `user_directory_search`. To be joined to `user_directory`. It contains an extra column that enables full text search based on user ids and display names. Different schemas for SQLite and Postgres with different code paths to match.

  - Indexed on the full text search data. Indexed on users.

- `user_directory_stream_pos`. When the initial background update to populate the directory is complete, we record a stream position here. This indicates that synapse should now listen for room changes and incrementally update the directory where necessary.

- `users_in_public_rooms`. Contains associations between users and the public rooms they're in. Used to determine which users are in public rooms and should be publicly visible in the directory.

- `users_who_share_private_rooms`. Rows are triples `(L, M, room id)` where `L` is a local user and `M` is a local or remote user. `L` and `M` should be different, but this isn't enforced by a constraint.

# Message retention policies

Synapse admins can enable support for message retention policies on their homeserver. Message retention policies exist at a room level, follow the semantics described in MSC1763, and allow server and room admins to configure how long messages should be kept in a homeserver's database before being purged from it. Please note that, as this feature isn't part of the Matrix specification yet, this implementation is to be considered as experimental.

A message retention policy is mainly defined by its `max_lifetime` parameter, which defines how long a message can be kept around after it was sent to the room. If a room doesn't have a message retention policy, and there's no default one for a given server, then no message sent in that room is ever purged on that server.

MSC1763 also specifies semantics for a `min_lifetime` parameter which defines the amount of time after which an event can get purged (after it was sent to the room), but Synapse doesn't currently support it beyond registering it.

Both `max_lifetime` and `min_lifetime` are optional parameters.

Note that message retention policies don't apply to state events.

Once an event reaches its expiry date (defined as the time it was sent plus the value for `max_lifetime` in the room), two things happen:

- Synapse stops serving the event to clients via any endpoint.
- The message gets picked up by the next purge job (see the "Purge jobs" section) and is removed from Synapse's database.

Since purge jobs don't run continuously, this means that an event might stay in a server's database for longer than the value for `max_lifetime` in the room would allow, though hidden from clients.

Similarly, if a server (with support for message retention policies enabled) receives from another server an event that should have been purged according to its room's policy, then the receiving server will process and store that event until it's picked up by the next purge job, though it will always hide it from clients.

Synapse requires at least one message in each room, so it will never delete the last message in a room. It will, however, hide it from clients.

## Server configuration

Support for this feature can be enabled and configured in the `retention` section of the Synapse configuration file (see the sample file).

To enable support for message retention policies, set the setting `enabled` in this section to `true`.

### Default policy

A default message retention policy is a policy defined in Synapse's configuration that is used by Synapse for every room that doesn't have a message retention policy configured in its state. This allows server admins to ensure that messages are never kept indefinitely in a server's database.

A default policy can be defined as such, in the `retention` section of the configuration file:

      default_policy:
        min_lifetime: 1d
        max_lifetime: 1y

Here, `min_lifetime` and `max_lifetime` have the same meaning and level of support as previously described. They can be expressed either as a duration (using the units `s` (seconds), `m` (minutes), `h` (hours), `d` (days), `w` (weeks) and `y` (years)) or as a number of milliseconds.

### Purge jobs

Purge jobs are the jobs that Synapse runs in the background to purge expired events from the database. They are only run if support for message retention policies is enabled in the server's configuration. If no configuration for purge jobs is configured by the server admin, Synapse will use a default configuration, which is described in the sample configuration file.

Some server admins might want a finer control on when events are removed depending on an event's room's policy. This can be done by setting the `purge_jobs` sub-section in the `retention` section of the configuration file. An example of such configuration could be:

      purge_jobs:
        - longest_max_lifetime: 3d
          interval: 12h
        - shortest_max_lifetime: 3d
          longest_max_lifetime: 1w
          interval: 1d
        - shortest_max_lifetime: 1w
          interval: 2d

In this example, we define three jobs:

- one that runs twice a day (every 12 hours) and purges events in rooms which policy's `max_lifetime` is lower or equal to 3 days.
- one that runs once a day and purges events in rooms which policy's `max_lifetime` is between 3 days and a week.
- one that runs once every 2 days and purges events in rooms which policy's `max_lifetime` is greater than a week.

Note that this example is tailored to show different configurations and features slightly more jobs than it's probably necessary (in practice, a server admin would probably consider it better to replace the two last jobs with one that runs once a day and handles rooms which which policy's `max_lifetime` is greater than 3 days).

Keep in mind, when configuring these jobs, that a purge job can become quite heavy on the server if it targets many rooms, therefore prefer having jobs with a low interval that target a limited set of rooms. Also make sure to include a job with no minimum and one with no maximum to make sure your configuration handles every policy.

As previously mentioned in this documentation, while a purge job that runs e.g. every day means that an expired event might stay in the database for up to a day after its expiry, Synapse hides expired events from clients as soon as they expire, so the event is not visible to local users between its expiry date and the moment it gets purged from the server's database.

### Lifetime limits

Server admins can set limits on the values of `max_lifetime` to use when purging old events in a room. These limits can be defined as such in the `retention` section of the configuration file:

      allowed_lifetime_min: 1d
      allowed_lifetime_max: 1y

The limits are considered when running purge jobs. If necessary, the effective value of `max_lifetime` will be brought between `allowed_lifetime_min` and `allowed_lifetime_max` (inclusive). This means that, if the value of `max_lifetime` defined in the room's state is lower than `allowed_lifetime_min`, the value of `allowed_lifetime_min` will be used instead. Likewise, if the value of `max_lifetime` is higher than `allowed_lifetime_max`, the value of `allowed_lifetime_max` will be used instead.

In the example above, we ensure Synapse never deletes events that are less than one day old, and that it always deletes events that are over a year old.

If a default policy is set, and its `max_lifetime` value is lower than `allowed_lifetime_min` or higher than `allowed_lifetime_max`, the same process applies.

Both parameters are optional; if one is omitted Synapse won't use it to adjust the effective value of `max_lifetime`.

Like other settings in this section, these parameters can be expressed either as a duration or as a number of milliseconds.

## Room configuration

To configure a room's message retention policy, a room's admin or moderator needs to send a state event in that room with the type `m.room.retention` and the following content:

    {
        "max_lifetime": ...
    }

In this event's content, the `max_lifetime` parameter has the same meaning as previously described, and needs to be expressed in milliseconds. The event's content can also include a `min_lifetime` parameter, which has the same meaning and limited support as previously described.

Note that over every server in the room, only the ones with support for message retention policies will actually remove expired events. This support is currently not enabled by default in Synapse.

## Note on reclaiming disk space

While purge jobs actually delete data from the database, the disk space used by the database might not decrease immediately on the database's host. However, even though the database engine won't free up the disk space, it will start writing new data into where the purged data was.

If you want to reclaim the freed disk space anyway and return it to the operating system, the server admin needs to run `VACUUM FULL;` (or `VACUUM;` for SQLite databases) on Synapse's database (see the related PostgreSQL documentation).

# Modules

Synapse supports extending its functionality by configuring external modules.

Note: When using third-party modules, you effectively allow someone else to run custom code on your Synapse homeserver. Server admins are encouraged to verify the provenance of the modules they use on their homeserver and make sure the modules aren't running malicious code on their instance.

## Using modules

To use a module on Synapse, add it to the `modules` section of the configuration file:

    modules:
      - module: my_super_module.MySuperClass
        config:
          do_thing: true
      - module: my_other_super_module.SomeClass
        config: {}

Each module is defined by a path to a Python class as well as a configuration. This information for a given module should be available in the module's own documentation.

## Using multiple modules

The order in which modules are listed in this section is important. When processing an action that can be handled by several modules, Synapse will always prioritise the module that appears first (i.e. is the highest in the list). This means:

- If several modules register the same callback, the callback registered by the module that appears first is used.
- If several modules try to register a handler for the same HTTP path, only the handler registered by the module that appears first is used. Handlers registered by the other module(s) are ignored and Synapse will log a warning message about them.

Note that Synapse doesn't allow multiple modules implementing authentication checkers via the password auth provider feature for the same login type with different fields. If this happens, Synapse will refuse to start.

## Current status

We are currently in the process of migrating module interfaces to this system. While some interfaces might be compatible with it, others still require configuring modules in another part of Synapse's configuration file.

Currently, only the following pre-existing interfaces are compatible with this new system:

- spam checker
- third-party rules
- presence router
- password auth providers

# Writing a module

A module is a Python class that uses Synapse's module API to interact with the homeserver. It can register callbacks that Synapse will call on specific operations, as well as web resources to attach to Synapse's web server.

When instantiated, a module is given its parsed configuration as well as an instance of the `synapse.module_api.ModuleApi` class. The configuration is a dictionary, and is either the output of the module's `parse_config` static method (see below), or the configuration associated with the module in Synapse's configuration file.

See the documentation for the `ModuleApi` class here.

## When Synapse runs with several modules configured

If Synapse is running with other modules configured, the order each module appears in within the `modules` section of the Synapse configuration file might restrict what it can or cannot register. See this section for more information.

On top of the rules listed in the link above, if a callback returns a value that should cause the current operation to fail (e.g. if a callback checking an event returns with a value that should cause the event to be denied), Synapse will fail the operation and ignore any subsequent callbacks that should have been run after this one.

The documentation for each callback mentions how Synapse behaves when multiple modules implement it.

## Handling the module's configuration

A module can implement the following static method:

    @staticmethod
    def parse_config(config: dict) -> dict

This method is given a dictionary resulting from parsing the YAML configuration for the module. It may modify it (for example by parsing durations expressed as strings (e.g. "5d") into milliseconds, etc.), and return the modified dictionary. It may also verify that the configuration is correct, and raise an instance of `synapse.module_api.errors.ConfigError` if not.

## Registering a web resource

Modules can register web resources onto Synapse's web server using the following module API method:

    def ModuleApi.register_web_resource(path: str, resource: IResource) -> None

The path is the full absolute path to register the resource at. For example, if you register a resource for the path `/_synapse/client/my_super_module/say_hello`, Synapse will serve it at `http(s)://[HS_URL]/_synapse/client/my_super_module/say_hello`. Note that Synapse does not allow registering resources for several sub-paths in the `/_matrix` namespace (such as anything under `/_matrix/client` for example). It is strongly recommended that modules register their web resources under the `/_synapse/client` namespace.

The provided resource is a Python class that implements Twisted's IResource interface (such as Resource).

Only one resource can be registered for a given path. If several modules attempt to register a resource for the same path, the module that appears first in Synapse's configuration file takes priority.

Modules must register their web resources in their `__init__` method.

## Registering a callback

Modules can use Synapse's module API to register callbacks. Callbacks are functions that Synapse will call when performing specific actions. Callbacks must be asynchronous, and are split in categories. A single module may implement callbacks from multiple categories, and is under no obligation to implement all callbacks from the categories it registers callbacks for.

Modules can register callbacks using one of the module API's `register_[...]_callbacks` methods. The callback functions are passed to these methods as keyword arguments, with the callback name as the argument name and the function as its value. This is demonstrated in the example below. A `register_[...]_callbacks` method exists for each category.

Callbacks for each category can be found on their respective page of the Synapse documentation website.

# Spam checker callbacks

Spam checker callbacks allow module developers to implement spam mitigation actions for Synapse instances. Spam checker callbacks can be registered using the module API's `register_spam_checker_callbacks` method.

## Callbacks

The available spam checker callbacks are:

### `check_event_for_spam`

First introduced in Synapse v1.37.0

    async def check_event_for_spam(event: "synapse.events.EventBase") -> Union[bool, str]

Called when receiving an event from a client or via federation. The module can return either a `bool` to indicate whether the event must be rejected because of spam, or a `str` to indicate the event must be rejected because of spam and to give a rejection reason to forward to clients.

If multiple modules implement this callback, they will be considered in order. If a callback returns `False`, Synapse falls through to the next one. The value of the first callback that does not return `False` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_join_room`

First introduced in Synapse v1.37.0

    async def user_may_join_room(user: str, room: str, is_invited: bool) -> bool

Called when a user is trying to join a room. The module must return a `bool` to indicate whether the user can join the room. The user is represented by their Matrix user ID (e.g. `@alice:example.com`) and the room is represented by its Matrix ID (e.g. `!room:example.com`). The module is also given a boolean to indicate whether the user currently has a pending invite in the room.

This callback isn't called if the join is performed by a server administrator, or in the context of a room creation.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_invite`

First introduced in Synapse v1.37.0

    async def user_may_invite(inviter: str, invitee: str, room_id: str) -> bool

Called when processing an invitation. The module must return a `bool` indicating whether the inviter can invite the invitee to the given room. Both inviter and invitee are represented by their Matrix user ID (e.g. `@alice:example.com`).

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_send_3pid_invite`

First introduced in Synapse v1.45.0

    async def user_may_send_3pid_invite(
        inviter: str,
        medium: str,
        address: str,
        room_id: str,
    ) -> bool

Called when processing an invitation using a third-party identifier (also called a 3PID, e.g. an email address or a phone number). The module must return a `bool` indicating whether the inviter can invite the invitee to the given room.

The inviter is represented by their Matrix user ID (e.g. `@alice:example.com`), and the invitee is represented by its medium (e.g. "email") and its address (e.g. `alice@example.com`). See the Matrix specification for more information regarding third-party identifiers.

For example, a call to this callback to send an invitation to the email address `alice@example.com` would look like this:

    await user_may_send_3pid_invite(
        "@bob:example.com",  # The inviter's user ID
        "email",  # The medium of the 3PID to invite
        "alice@example.com",  # The address of the 3PID to invite
        "!some_room:example.com",  # The ID of the room to send the invite into
    )

Note: If the third-party identifier is already associated with a matrix user ID, `user_may_invite` will be used instead.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_create_room`

First introduced in Synapse v1.37.0

    async def user_may_create_room(user: str) -> bool

Called when processing a room creation request. The module must return a `bool` indicating whether the given user (represented by their Matrix user ID) is allowed to create a room.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_create_room_with_invites`

First introduced in Synapse v1.44.0

    async def user_may_create_room_with_invites(
        user: str,
        invites: List[str],
        threepid_invites: List[Dict[str, str]],
    ) -> bool

Called when processing a room creation request (right after `user_may_create_room`). The module is given the Matrix user ID of the user trying to create a room, as well as a list of Matrix users to invite and a list of third-party identifiers (3PID, e.g. email addresses) to invite.

An invited Matrix user to invite is represented by their Matrix user IDs, and an invited 3PIDs is represented by a dict that includes the 3PID medium (e.g. "email") through its `medium` key and its address (e.g. "alice@example.com") through its `address` key.

See the Matrix specification for more information regarding third-party identifiers.

If no invite and/or 3PID invite were specified in the room creation request, the corresponding list(s) will be empty.

Note: This callback is not called when a room is cloned (e.g. during a room upgrade) since no invites are sent when cloning a room. To cover this case, modules also need to implement `user_may_create_room`.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_create_room_alias`

First introduced in Synapse v1.37.0

    async def user_may_create_room_alias(user: str, room_alias: "synapse.types.RoomAlias") -> bool

Called when trying to associate an alias with an existing room. The module must return a `bool` indicating whether the given user (represented by their Matrix user ID) is allowed to set the given alias.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `user_may_publish_room`

First introduced in Synapse v1.37.0

    async def user_may_publish_room(user: str, room_id: str) -> bool

Called when trying to publish a room to the homeserver's public rooms directory. The module must return a `bool` indicating whether the given user (represented by their Matrix user ID) is allowed to publish the given room.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `check_username_for_spam`

First introduced in Synapse v1.37.0

    async def check_username_for_spam(user_profile: Dict[str, str]) -> bool

Called when computing search results in the user directory. The module must return a `bool` indicating whether the given user profile can appear in search results. The profile is represented as a dictionary with the following keys:

- `user_id`: The Matrix ID for this user.
- `display_name`: The user's display name.
- `avatar_url`: The `mxc://` URL to the user's avatar.

The module is given a copy of the original dictionary, so modifying it from within the module cannot modify a user's profile when included in user directory search results.

If multiple modules implement this callback, they will be considered in order. If a callback returns `False`, Synapse falls through to the next one. The value of the first callback that does not return `False` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `check_registration_for_spam`

First introduced in Synapse v1.37.0

    async def check_registration_for_spam(
        email_threepid: Optional[dict],
        username: Optional[str],
        request_info: Collection[Tuple[str, str]],
        auth_provider_id: Optional[str] = None,
    ) -> "synapse.spam_checker_api.RegistrationBehaviour"

Called when registering a new user. The module must return a `RegistrationBehaviour` indicating whether the registration can go through or must be denied, or whether the user may be allowed to register but will be shadow banned.

The arguments passed to this callback are:

- `email_threepid`: The email address used for registering, if any.
- `username`: The username the user would like to register. Can be `None`, meaning that Synapse will generate one later.
- `request_info`: A collection of tuples, which first item is a user agent, and which second item is an IP address. These user agents and IP addresses are the ones that were used during the registration process.
- `auth_provider_id`: The identifier of the SSO authentication provider, if any.

If multiple modules implement this callback, they will be considered in order. If a callback returns `RegistrationBehaviour.ALLOW`, Synapse falls through to the next one. The value of the first callback that does not return `RegistrationBehaviour.ALLOW` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `check_media_file_for_spam`

First introduced in Synapse v1.37.0

    async def check_media_file_for_spam(
        file_wrapper: "synapse.rest.media.v1.media_storage.ReadableFileWrapper",
        file_info: "synapse.rest.media.v1._base.FileInfo",
    ) -> bool

Called when storing a local or remote file. The module must return a boolean indicating whether the given file can be stored in the homeserver's media store.

If multiple modules implement this callback, they will be considered in order. If a callback returns `False`, Synapse falls through to the next one. The value of the first callback that does not return `False` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

## Example

The example below is a module that implements the spam checker callback `check_event_for_spam` to deny any message sent by users whose Matrix user IDs are mentioned in a configured list, and registers a web resource to the path `/_synapse/client/list_spam_checker/is_evil` that returns a JSON object indicating whether the provided user appears in that list.

    import json
    from typing import Union

    from twisted.web.resource import Resource
    from twisted.web.server import Request

    from synapse.module_api import ModuleApi

    class IsUserEvilResource(Resource):
        def __init__(self, config):
            super(IsUserEvilResource, self).__init__()
            self.evil_users = config.get("evil_users") or []

        def render_GET(self, request: Request):
            user = request.args.get(b"user")[0].decode()
            request.setHeader(b"Content-Type", b"application/json")
            return json.dumps({"evil": user in self.evil_users}).encode()

    class ListSpamChecker:
        def __init__(self, config: dict, api: ModuleApi):
            self.api = api
            self.evil_users = config.get("evil_users") or []

            self.api.register_spam_checker_callbacks(
                check_event_for_spam=self.check_event_for_spam,
            )

            self.api.register_web_resource(
                path="/_synapse/client/list_spam_checker/is_evil",
                resource=IsUserEvilResource(config),
            )

        async def check_event_for_spam(self, event: "synapse.events.EventBase") -> Union[bool, str]:
            return event.sender not in self.evil_users

# Third party rules callbacks

Third party rules callbacks allow module developers to add extra checks to verify the validity of incoming events. Third party event rules callbacks can be registered using the module API's `register_third_party_rules_callbacks` method.

## Callbacks

The available third party rules callbacks are:

### `check_event_allowed`

First introduced in Synapse v1.39.0

    async def check_event_allowed(
        event: "synapse.events.EventBase",
        state_events: "synapse.types.StateMap",
    ) -> Tuple[bool, Optional[dict]]

This callback is very experimental and can and will break without notice. Module developers are encouraged to implement `check_event_for_spam` from the spam checker category instead.

Called when processing any incoming event, with the event and a `StateMap` representing the current state of the room the event is being sent into. A `StateMap` is a dictionary that maps tuples containing an event type and a state key to the corresponding state event. For example retrieving the room's `m.room.create` event from the `state_events` argument would look like this: `state_events.get(("m.room.create", ""))`. The module must return a boolean indicating whether the event can be allowed.

Note that this callback function processes incoming events coming via federation traffic (on top of client traffic). This means denying an event might cause the local copy of the room's history to diverge from that of remote servers. This may cause federation issues in the room. It is strongly recommended to only deny events using this callback function if the sender is a local user, or in a private federation in which all servers are using the same module, with the same configuration.

If the boolean returned by the module is `True`, it may also tell Synapse to replace the event with new data by returning the new event's data as a dictionary. In order to do that, it is recommended the module calls `event.get_dict()` to get the current event as a dictionary, and modify the returned dictionary accordingly.

Note that replacing the event only works for events sent by local users, not for events received over federation.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `on_create_room`

First introduced in Synapse v1.39.0

    async def on_create_room(
        requester: "synapse.types.Requester",
        request_content: dict,
        is_requester_admin: bool,
    ) -> None

Called when processing a room creation request, with the `Requester` object for the user performing the request, a dictionary representing the room creation request's JSON body (see the spec for a list of possible parameters), and a boolean indicating whether the user performing the request is a server admin.

Modules can modify the `request_content` (by e.g. adding events to its `initial_state`), or deny the room's creation by raising a `module_api.errors.SynapseError`.

If multiple modules implement this callback, they will be considered in order. If a callback returns without raising an exception, Synapse falls through to the next one. The room creation will be forbidden as soon as one of the callbacks raises an exception. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `check_threepid_can_be_invited`

First introduced in Synapse v1.39.0

    async def check_threepid_can_be_invited(
        medium: str,
        address: str,
        state_events: "synapse.types.StateMap",
    ) -> bool:

Called when processing an invite via a third-party identifier (i.e. email or phone number). The module must return a boolean indicating whether the invite can go through.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `check_visibility_can_be_modified`

First introduced in Synapse v1.39.0

    async def check_visibility_can_be_modified(
        room_id: str,
        state_events: "synapse.types.StateMap",
        new_visibility: str,
    ) -> bool:

Called when changing the visibility of a room in the local public room directory. The visibility is a string that's either "public" or "private". The module must return a boolean indicating whether the change can go through.

If multiple modules implement this callback, they will be considered in order. If a callback returns `True`, Synapse falls through to the next one. The value of the first callback that does not return `True` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

## Example

The example below is a module that implements the third-party rules callback `check_event_allowed` to censor incoming messages as dictated by a third-party service.

    from typing import Optional, Tuple

    from synapse.module_api import ModuleApi

    _DEFAULT_CENSOR_ENDPOINT = "https://my-internal-service.local/censor-event"

    class EventCensorer:
        def __init__(self, config: dict, api: ModuleApi):
            self.api = api
            self._endpoint = config.get("endpoint", _DEFAULT_CENSOR_ENDPOINT)

            self.api.register_third_party_rules_callbacks(
                check_event_allowed=self.check_event_allowed,
            )

        async def check_event_allowed(
            self,
            event: "synapse.events.EventBase",
            state_events: "synapse.types.StateMap",
        ) -> Tuple[bool, Optional[dict]]:
            event_dict = event.get_dict()
            new_event_content = await self.api.http_client.post_json_get_json(
                uri=self._endpoint, post_json=event_dict,
            )
            event_dict["content"] = new_event_content
            return event_dict

# Presence router callbacks

Presence router callbacks allow module developers to specify additional users (local or remote) to receive certain presence updates from local users. Presence router callbacks can be registered using the module API's `register_presence_router_callbacks` method.

## Callbacks

The available presence router callbacks are:

### `get_users_for_states`

First introduced in Synapse v1.42.0

    async def get_users_for_states(
        state_updates: Iterable["synapse.api.UserPresenceState"],
    ) -> Dict[str, Set["synapse.api.UserPresenceState"]]

Requires `get_interested_users` to also be registered

Called when processing updates to the presence state of one or more users. This callback can be used to instruct the server to forward that presence state to specific users. The module must return a dictionary that maps from Matrix user IDs (which can be local or remote) to the `UserPresenceState` changes that they should be forwarded.

Synapse will then attempt to send the specified presence updates to each user when possible.

If multiple modules implement this callback, Synapse merges all the dictionaries returned by the callbacks. If multiple callbacks return a dictionary containing the same key, Synapse concatenates the sets associated with this key from each dictionary.

### `get_interested_users`

First introduced in Synapse v1.42.0

    async def get_interested_users(
        user_id: str
    ) -> Union[Set[str], "synapse.module_api.PRESENCE_ALL_USERS"]

Requires `get_users_for_states` to also be registered

Called when determining which users someone should be able to see the presence state of. This callback should return complementary results to `get_users_for_state` or the presence information may not be properly forwarded.

The callback is given the Matrix user ID for a local user that is requesting presence data and should return the Matrix user IDs of the users whose presence state they are allowed to query. The returned users can be local or remote.

Alternatively the callback can return `synapse.module_api.PRESENCE_ALL_USERS` to indicate that the user should receive updates from all known users.

If multiple modules implement this callback, they will be considered in order. Synapse calls each callback one by one, and use a concatenation of all the `set`s returned by the callbacks. If one callback returns `synapse.module_api.PRESENCE_ALL_USERS`, Synapse uses this value instead. If this happens, Synapse does not call any of the subsequent implementations of this callback.

## Example

The example below is a module that implements both presence router callbacks, and ensures that `@alice:example.org` receives all presence updates from `@bob:example.com` and `@charlie:somewhere.org`, regardless of whether Alice shares a room with any of them.

    from typing import Dict, Iterable, Set, Union

    from synapse.module_api import ModuleApi

    class CustomPresenceRouter:
        def __init__(self, config: dict, api: ModuleApi):
            self.api = api

            self.api.register_presence_router_callbacks(
                get_users_for_states=self.get_users_for_states,
                get_interested_users=self.get_interested_users,
            )

        async def get_users_for_states(
            self,
            state_updates: Iterable["synapse.api.UserPresenceState"],
        ) -> Dict[str, Set["synapse.api.UserPresenceState"]]:
            res = {}
            for update in state_updates:
                if (
                    update.user_id == "@bob:example.com"
                    or update.user_id == "@charlie:somewhere.org"
                ):
                    res.setdefault("@alice:example.com", set()).add(update)

            return res

        async def get_interested_users(
            self,
            user_id: str,
        ) -> Union[Set[str], "synapse.module_api.PRESENCE_ALL_USERS"]:
            if user_id == "@alice:example.com":
                return {"@bob:example.com", "@charlie:somewhere.org"}

            return set()

# Account validity callbacks

Account validity callbacks allow module developers to add extra steps to verify the validity on an account, i.e. see if a user can be granted access to their account on the Synapse instance. Account validity callbacks can be registered using the module API's `register_account_validity_callbacks` method.

The available account validity callbacks are:

### `is_user_expired`

First introduced in Synapse v1.39.0

    async def is_user_expired(user: str) -> Optional[bool]

Called when processing any authenticated request (except for logout requests). The module can return a `bool` to indicate whether the user has expired and should be locked out of their account, or `None` if the module wasn't able to figure it out. The user is represented by their Matrix user ID (e.g. `@alice:example.com`).

If the module returns `True`, the current request will be denied with the error code `ORG_MATRIX_EXPIRED_ACCOUNT` and the HTTP status code 403. Note that this doesn't invalidate the user's access token.

If multiple modules implement this callback, they will be considered in order. If a callback returns `None`, Synapse falls through to the next one. The value of the first callback that does not return `None` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback.

### `on_user_registration`

First introduced in Synapse v1.39.0

    async def on_user_registration(user: str) -> None

Called after successfully registering a user, in case the module needs to perform extra operations to keep track of them. (e.g. add them to a database table). The user is represented by their Matrix user ID.

If multiple modules implement this callback, Synapse runs them all in order.

# Password auth provider callbacks

Password auth providers offer a way for server administrators to integrate their Synapse installation with an external authentication system. The callbacks can be registered by using the Module API's `register_password_auth_provider_callbacks` method.

## Callbacks

### `auth_checkers`

First introduced in Synapse v1.46.0

     auth_checkers: Dict[Tuple[str,Tuple], Callable]

A dict mapping from tuples of a login type identifier (such as `m.login.password`) and a tuple of field names (such as `("password", "secret_thing")`) to authentication checking callbacks, which should be of the following form:

    async def check_auth(
        user: str,
        login_type: str,
        login_dict: "synapse.module_api.JsonDict",
    ) -> Optional[
        Tuple[
            str,
            Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]]
        ]
    ]

The login type and field names should be provided by the user in the request to the `/login` API. The Matrix specification defines some types, however user defined ones are also allowed.

The callback is passed the `user` field provided by the client (which might not be in `@username:server` form), the login type, and a dictionary of login secrets passed by the client.

If the authentication is successful, the module must return the user's Matrix ID (e.g. `@alice:example.com`) and optionally a callback to be called with the response to the `/login` request. If the module doesn't wish to return a callback, it must return `None` instead.

If the authentication is unsuccessful, the module must return `None`.

If multiple modules register an auth checker for the same login type but with different fields, Synapse will refuse to start.

If multiple modules register an auth checker for the same login type with the same fields, then the callbacks will be executed in order, until one returns a Matrix User ID (and optionally a callback). In that case, the return value of that callback will be accepted and subsequent callbacks will not be fired. If every callback returns `None`, then the authentication fails.

### `check_3pid_auth`

First introduced in Synapse v1.46.0

    async def check_3pid_auth(
        medium: str,
        address: str,
        password: str,
    ) -> Optional[
        Tuple[
            str,
            Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]]
        ]
    ]

Called when a user attempts to register or log in with a third party identifier, such as email. It is passed the medium (eg. `email`), an address (eg. `jdoe@example.com`) and the user's password.

If the authentication is successful, the module must return the user's Matrix ID (e.g. `@alice:example.com`) and optionally a callback to be called with the response to the `/login` request. If the module doesn't wish to return a callback, it must return None instead.

If the authentication is unsuccessful, the module must return `None`.

If multiple modules implement this callback, they will be considered in order. If a callback returns `None`, Synapse falls through to the next one. The value of the first callback that does not return `None` will be used. If this happens, Synapse will not call any of the subsequent implementations of this callback. If every callback return `None`, the authentication is denied.

### `on_logged_out`

First introduced in Synapse v1.46.0

    async def on_logged_out(
        user_id: str,
        device_id: Optional[str],
        access_token: str
    ) -> None

Called during a logout request for a user. It is passed the qualified user ID, the ID of the deactivated device (if any: access tokens are occasionally created without an associated device ID), and the (now deactivated) access token.

If multiple modules implement this callback, Synapse runs them all in order.

## Example

The example module below implements authentication checkers for two different login types:

- `my.login.type`
  - Expects a `my_field` field to be sent to `/login`
  - Is checked by the method: `self.check_my_login`
- `m.login.password` (defined in the spec)
  - Expects a `password` field to be sent to `/login`
  - Is checked by the method: `self.check_pass`

    from typing import Awaitable, Callable, Optional, Tuple

    import synapse
    from synapse import module_api

    class MyAuthProvider:
        def __init__(self, config: dict, api: module_api):

            self.api = api

            self.credentials = {
                "bob": "building",
                "@scoop:matrix.org": "digging",
            }

            api.register_password_auth_provider_callbacks(
                auth_checkers={
                    ("my.login_type", ("my_field",)): self.check_my_login,
                    ("m.login.password", ("password",)): self.check_pass,
                },
            )

        async def check_my_login(
            self,
            username: str,
            login_type: str,
            login_dict: "synapse.module_api.JsonDict",
        ) -> Optional[
            Tuple[
                str,
                Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]],
            ]
        ]:
            if login_type != "my.login_type":
                return None

            if self.credentials.get(username) == login_dict.get("my_field"):
                return self.api.get_qualified_user_id(username)

        async def check_pass(
            self,
            username: str,
            login_type: str,
            login_dict: "synapse.module_api.JsonDict",
        ) -> Optional[
            Tuple[
                str,
                Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]],
            ]
        ]:
            if login_type != "m.login.password":
                return None

            if self.credentials.get(username) == login_dict.get("password"):
                return self.api.get_qualified_user_id(username)

# Porting an existing module that uses the old interface

In order to port a module that uses Synapse's old module interface, its author needs to:

- ensure the module's callbacks are all asynchronous.
- register their callbacks using one or more of the `register_[...]_callbacks` methods from the `ModuleApi` class in the module's `__init__` method (see this section for more info).

Additionally, if the module is packaged with an additional web resource, the module should register this resource in its `__init__` method using the `register_web_resource` method from the `ModuleApi` class (see this section for more info).

There is no longer a `get_db_schema_files` callback provided for password auth provider modules. Any changes to the database should now be made by the module using the module API class.

The module's author should also update any example in the module's configuration to only use the new `modules` section in Synapse's configuration file (see this section for more info).

# Scaling synapse via workers

For small instances it recommended to run Synapse in the default monolith mode. For larger instances where performance is a concern it can be helpful to split out functionality into multiple separate python processes. These processes are called 'workers', and are (eventually) intended to scale horizontally independently.

Synapse's worker support is under active development and subject to change as we attempt to rapidly scale ever larger Synapse instances. However we are documenting it here to help admins needing a highly scalable Synapse instance similar to the one running `matrix.org`.

All processes continue to share the same database instance, and as such, workers only work with PostgreSQL-based Synapse deployments. SQLite should only be used for demo purposes and any admin considering workers should already be running PostgreSQL.

See also Matrix.org blog post for a higher level overview.

## Main process/worker communication

The processes communicate with each other via a Synapse-specific protocol called 'replication' (analogous to MySQL- or Postgres-style database replication) which feeds streams of newly written data between processes so they can be kept in sync with the database state.

When configured to do so, Synapse uses a Redis pub/sub channel to send the replication stream between all configured Synapse processes. Additionally, processes may make HTTP requests to each other, primarily for operations which need to wait for a reply ─ such as sending an event.

Redis support was added in v1.13.0 with it becoming the recommended method in v1.18.0. It replaced the old direct TCP connections (which is deprecated as of v1.18.0) to the main process. With Redis, rather than all the workers connecting to the main process, all the workers and the main process connect to Redis, which relays replication commands between processes. This can give a significant cpu saving on the main process and will be a prerequisite for upcoming performance improvements.

If Redis support is enabled Synapse will use it as a shared cache, as well as a pub/sub mechanism.

See the Architectural diagram section at the end for a visualisation of what this looks like.

## Setting up workers

A Redis server is required to manage the communication between the processes. The Redis server should be installed following the normal procedure for your distribution (e.g. `apt install redis-server` on Debian). It is safe to use an existing Redis deployment if you have one.

Once installed, check that Redis is running and accessible from the host running Synapse, for example by executing `echo PING | nc -q1 localhost 6379` and seeing a response of `+PONG`.

The appropriate dependencies must also be installed for Synapse. If using a virtualenv, these can be installed with:

    pip install "matrix-synapse[redis]"

Note that these dependencies are included when synapse is installed with `pip install matrix-synapse[all]`. They are also included in the debian packages from `matrix.org` and in the docker images at https://hub.docker.com/r/matrixdotorg/synapse/.

To make effective use of the workers, you will need to configure an HTTP reverse-proxy such as nginx or haproxy, which will direct incoming requests to the correct worker, or to the main synapse instance. See the reverse proxy documentation for information on setting up a reverse proxy.

When using workers, each worker process has its own configuration file which contains settings specific to that worker, such as the HTTP listener that it provides (if any), logging configuration, etc.

Normally, the worker processes are configured to read from a shared configuration file as well as the worker-specific configuration files. This makes it easier to keep common configuration settings synchronised across all the processes.

The main process is somewhat special in this respect: it does not normally need its own configuration file and can take all of its configuration from the shared configuration file.

### Shared configuration

Normally, only a couple of changes are needed to make an existing configuration file suitable for use with workers. First, you need to enable an "HTTP replication listener" for the main process; and secondly, you need to enable redis-based replication. Optionally, a shared secret can be used to authenticate HTTP traffic between workers. For example:

    # extend the existing `listeners` section. This defines the ports that the
    # main process will listen on.
    listeners:
      # The HTTP replication port
      - port: 9093
        bind_address: '127.0.0.1'
        type: http
        resources:
         - names: [replication]

    # Add a random shared secret to authenticate traffic.
    worker_replication_secret: ""

    redis:
        enabled: true

See the sample config for the full documentation of each option.

Under no circumstances should the replication listener be exposed to the public internet; it has no authentication and is unencrypted.

### Worker configuration

In the config file for each worker, you must specify the type of worker application (`worker_app`), and you should specify a unique name for the worker (`worker_name`). The currently available worker applications are listed below. You must also specify the HTTP replication endpoint that it should talk to on the main synapse process. `worker_replication_host` should specify the host of the main synapse and `worker_replication_http_port` should point to the HTTP replication port. If the worker will handle HTTP requests then the `worker_listeners` option should be set with a `http` listener, in the same way as the `listeners` option in the shared config.

For example:

    worker_app: synapse.app.generic_worker
    worker_name: worker1

    # The replication listener on the main synapse process.
    worker_replication_host: 127.0.0.1
    worker_replication_http_port: 9093

    worker_listeners:
     - type: http
       port: 8083
       resources:
         - names:
           - client
           - federation

    worker_log_config: /home/matrix/synapse/config/worker1_log_config.yaml

...is a full configuration for a generic worker instance, which will expose a plain HTTP endpoint on port 8083 separately serving various endpoints, e.g. `/sync`, which are listed below.

Obviously you should configure your reverse-proxy to route the relevant endpoints to the worker (`localhost:8083` in the above example).

### Running Synapse with workers

Finally, you need to start your worker processes. This can be done with either `synctl` or your distribution's preferred service manager such as `systemd`. We recommend the use of `systemd` where available: for information on setting up `systemd` to start synapse workers, see Systemd with Workers. To use `synctl`, see Using synctl with Workers.

## Available worker applications

### `synapse.app.generic_worker`

This worker can handle API requests matching the following regular expressions:

    # Sync requests
    ^/_matrix/client/(v2_alpha|r0)/sync$
    ^/_matrix/client/(api/v1|v2_alpha|r0)/events$
    ^/_matrix/client/(api/v1|r0)/initialSync$
    ^/_matrix/client/(api/v1|r0)/rooms/[^/]+/initialSync$

    # Federation requests
    ^/_matrix/federation/v1/event/
    ^/_matrix/federation/v1/state/
    ^/_matrix/federation/v1/state_ids/
    ^/_matrix/federation/v1/backfill/
    ^/_matrix/federation/v1/get_missing_events/
    ^/_matrix/federation/v1/publicRooms
    ^/_matrix/federation/v1/query/
    ^/_matrix/federation/v1/make_join/
    ^/_matrix/federation/v1/make_leave/
    ^/_matrix/federation/v1/send_join/
    ^/_matrix/federation/v2/send_join/
    ^/_matrix/federation/v1/send_leave/
    ^/_matrix/federation/v2/send_leave/
    ^/_matrix/federation/v1/invite/
    ^/_matrix/federation/v2/invite/
    ^/_matrix/federation/v1/query_auth/
    ^/_matrix/federation/v1/event_auth/
    ^/_matrix/federation/v1/exchange_third_party_invite/
    ^/_matrix/federation/v1/user/devices/
    ^/_matrix/federation/v1/get_groups_publicised$
    ^/_matrix/key/v2/query
    ^/_matrix/federation/unstable/org.matrix.msc2946/spaces/
    ^/_matrix/federation/unstable/org.matrix.msc2946/hierarchy/

    # Inbound federation transaction request
    ^/_matrix/federation/v1/send/

    # Client API requests
    ^/_matrix/client/(api/v1|r0|unstable)/createRoom$
    ^/_matrix/client/(api/v1|r0|unstable)/publicRooms$
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/joined_members$
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/context/.*$
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/members$
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state$
    ^/_matrix/client/unstable/org.matrix.msc2946/rooms/.*/spaces$
    ^/_matrix/client/unstable/org.matrix.msc2946/rooms/.*/hierarchy$
    ^/_matrix/client/unstable/im.nheko.summary/rooms/.*/summary$
    ^/_matrix/client/(api/v1|r0|unstable)/account/3pid$
    ^/_matrix/client/(api/v1|r0|unstable)/devices$
    ^/_matrix/client/(api/v1|r0|unstable)/keys/query$
    ^/_matrix/client/(api/v1|r0|unstable)/keys/changes$
    ^/_matrix/client/versions$
    ^/_matrix/client/(api/v1|r0|unstable)/voip/turnServer$
    ^/_matrix/client/(api/v1|r0|unstable)/joined_groups$
    ^/_matrix/client/(api/v1|r0|unstable)/publicised_groups$
    ^/_matrix/client/(api/v1|r0|unstable)/publicised_groups/
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/event/
    ^/_matrix/client/(api/v1|r0|unstable)/joined_rooms$
    ^/_matrix/client/(api/v1|r0|unstable)/search$

    # Registration/login requests
    ^/_matrix/client/(api/v1|r0|unstable)/login$
    ^/_matrix/client/(r0|unstable)/register$
    ^/_matrix/client/unstable/org.matrix.msc3231/register/org.matrix.msc3231.login.registration_token/validity$

    # Event sending requests
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/redact
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/send
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state/
    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/(join|invite|leave|ban|unban|kick)$
    ^/_matrix/client/(api/v1|r0|unstable)/join/
    ^/_matrix/client/(api/v1|r0|unstable)/profile/

Additionally, the following REST endpoints can be handled for GET requests:

    ^/_matrix/federation/v1/groups/

Pagination requests can also be handled, but all requests for a given room must be routed to the same instance. Additionally, care must be taken to ensure that the purge history admin API is not used while pagination requests for the room are in flight:

    ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/messages$

Additionally, the following endpoints should be included if Synapse is configured to use SSO (you only need to include the ones for whichever SSO provider you're using):

    # for all SSO providers
    ^/_matrix/client/(api/v1|r0|unstable)/login/sso/redirect
    ^/_synapse/client/pick_idp$
    ^/_synapse/client/pick_username
    ^/_synapse/client/new_user_consent$
    ^/_synapse/client/sso_register$

    # OpenID Connect requests.
    ^/_synapse/client/oidc/callback$

    # SAML requests.
    ^/_synapse/client/saml2/authn_response$

    # CAS requests.
    ^/_matrix/client/(api/v1|r0|unstable)/login/cas/ticket$

Ensure that all SSO logins go to a single process. For multiple workers not handling the SSO endpoints properly, see #7530 and #9427.

Note that a HTTP listener with `client` and `federation` resources must be configured in the `worker_listeners` option in the worker config.

#### Load balancing

It is possible to run multiple instances of this worker app, with incoming requests being load-balanced between them by the reverse-proxy. However, different endpoints have different characteristics and so admins may wish to run multiple groups of workers handling different endpoints so that load balancing can be done in different ways.

For `/sync` and `/initialSync` requests it will be more efficient if all requests from a particular user are routed to a single instance. Extracting a user ID from the access token or `Authorization` header is currently left as an exercise for the reader. Admins may additionally wish to separate out `/sync` requests that have a `since` query parameter from those that don't (and `/initialSync`), as requests that don't are known as "initial sync" that happens when a user logs in on a new device and can be very resource intensive, so isolating these requests will stop them from interfering with other users ongoing syncs.

Federation and client requests can be balanced via simple round robin.

The inbound federation transaction request `^/_matrix/federation/v1/send/` should be balanced by source IP so that transactions from the same remote server go to the same process.

Registration/login requests can be handled separately purely to help ensure that unexpected load doesn't affect new logins and sign ups.

Finally, event sending requests can be balanced by the room ID in the URI (or the full URI, or even just round robin), the room ID is the path component after `/rooms/`. If there is a large bridge connected that is sending or may send lots of events, then a dedicated set of workers can be provisioned to limit the effects of bursts of events from that bridge on events sent by normal users.

#### Stream writers

Additionally, there is experimental support for moving writing of specific streams (such as events) off of the main process to a particular worker. (This is only supported with Redis-based replication.)

Currently supported streams are `events` and `typing`.

To enable this, the worker must have a HTTP replication listener configured, have a `worker_name` and be listed in the `instance_map` config. For example to move event persistence off to a dedicated worker, the shared configuration would include:

    instance_map:
        event_persister1:
            host: localhost
            port: 8034

    stream_writers:
        events: event_persister1

The `events` stream also experimentally supports having multiple writers, where work is sharded between them by room ID. Note that you must restart all worker instances when adding or removing event persisters. An example `stream_writers` configuration with multiple writers:

    stream_writers:
        events:
            - event_persister1
            - event_persister2

#### Background tasks

There is also experimental support for moving background tasks to a separate worker. Background tasks are run periodically or started via replication. Exactly which tasks are configured to run depends on your Synapse configuration (e.g. if stats is enabled).

To enable this, the worker must have a `worker_name` and can be configured to run background tasks. For example, to move background tasks to a dedicated worker, the shared configuration would include:

    run_background_tasks_on: background_worker

You might also wish to investigate the `update_user_directory` and `media_instance_running_background_jobs` settings.

### `synapse.app.pusher`

Handles sending push notifications to sygnal and email. Doesn't handle any REST endpoints itself, but you should set `start_pushers: False` in the shared configuration file to stop the main synapse sending push notifications.

To run multiple instances at once the `pusher_instances` option should list all pusher instances by their worker name, e.g.:

    pusher_instances:
        - pusher_worker1
        - pusher_worker2

### `synapse.app.appservice`

Handles sending output traffic to Application Services. Doesn't handle any REST endpoints itself, but you should set `notify_appservices: False` in the shared configuration file to stop the main synapse sending appservice notifications.

Note this worker cannot be load-balanced: only one instance should be active.

### `synapse.app.federation_sender`

Handles sending federation traffic to other servers. Doesn't handle any REST endpoints itself, but you should set `send_federation: False` in the shared configuration file to stop the main synapse sending this traffic.

If running multiple federation senders then you must list each instance in the `federation_sender_instances` option by their `worker_name`. All instances must be stopped and started when adding or removing instances. For example:

    federation_sender_instances:
        - federation_sender1
        - federation_sender2

### `synapse.app.media_repository`

Handles the media repository. It can handle all endpoints starting with:

    /_matrix/media/

... and the following regular expressions matching media-specific administration APIs:

    ^/_synapse/admin/v1/purge_media_cache$
    ^/_synapse/admin/v1/room/.*/media.*$
    ^/_synapse/admin/v1/user/.*/media.*$
    ^/_synapse/admin/v1/media/.*$
    ^/_synapse/admin/v1/quarantine_media/.*$
    ^/_synapse/admin/v1/users/.*/media$

You should also set `enable_media_repo: False` in the shared configuration file to stop the main synapse running background jobs related to managing the media repository. Note that doing so will prevent the main process from being able to handle the above endpoints.

In the `media_repository` worker configuration file, configure the http listener to expose the `media` resource. For example:

        worker_listeners:
         - type: http
           port: 8085
           resources:
             - names:
               - media

Note that if running multiple media repositories they must be on the same server and you must configure a single instance to run the background tasks, e.g.:

        media_instance_running_background_jobs: "media-repository-1"

Note that if a reverse proxy is used , then `/_matrix/media/` must be routed for both inbound client and federation requests (if they are handled separately).

### `synapse.app.user_dir`

Handles searches in the user directory. It can handle REST endpoints matching the following regular expressions:

    ^/_matrix/client/(api/v1|r0|unstable)/user_directory/search$

When using this worker you must also set `update_user_directory: False` in the shared configuration file to stop the main synapse running background jobs related to updating the user directory.

### `synapse.app.frontend_proxy`

Proxies some frequently-requested client endpoints to add caching and remove load from the main synapse. It can handle REST endpoints matching the following regular expressions:

    ^/_matrix/client/(api/v1|r0|unstable)/keys/upload

If `use_presence` is False in the homeserver config, it can also handle REST endpoints matching the following regular expressions:

    ^/_matrix/client/(api/v1|r0|unstable)/presence/[^/]+/status

This "stub" presence handler will pass through `GET` request but make the `PUT` effectively a no-op.

It will proxy any requests it cannot handle to the main synapse instance. It must therefore be configured with the location of the main instance, via the `worker_main_http_uri` setting in the `frontend_proxy` worker configuration file. For example:

    worker_main_http_uri: http://127.0.0.1:8008

### Historical apps

Note: Historically there used to be more apps, however they have been amalgamated into a single `synapse.app.generic_worker` app. The remaining apps are ones that do specific processing unrelated to requests, e.g. the `pusher` that handles sending out push notifications for new events. The intention is for all these to be folded into the `generic_worker` app and to use config to define which processes handle the various proccessing such as push notifications.

## Migration from old config

There are two main independent changes that have been made: introducing Redis support and merging apps into `synapse.app.generic_worker`. Both these changes are backwards compatible and so no changes to the config are required, however server admins are encouraged to plan to migrate to Redis as the old style direct TCP replication config is deprecated.

To migrate to Redis add the `redis` config as above, and optionally remove the TCP `replication` listener from master and `worker_replication_port` from worker config.

To migrate apps to use `synapse.app.generic_worker` simply update the `worker_app` option in the worker configs, and where worker are started (e.g. in systemd service files, but not required for synctl).

## Architectural diagram

The following shows an example setup using Redis and a reverse proxy:

                         Clients & Federation
                                  |
                                  v
                            +-----------+
                            |           |
                            |  Reverse  |
                            |  Proxy    |
                            |           |
                            +-----------+
                                | | |
                                | | | HTTP requests
            +-------------------+ | +-----------+
            |                 +---+             |
            |                 |                 |
            v                 v                 v
    +--------------+  +--------------+  +--------------+  +--------------+
    |   Main       |  |   Generic    |  |   Generic    |  |  Event       |
    |   Process    |  |   Worker 1   |  |   Worker 2   |  |  Persister   |
    +--------------+  +--------------+  +--------------+  +--------------+
          ^    ^          |   ^   |         |   ^   |          ^    ^
          |    |          |   |   |         |   |   |          |    |
          |    |          |   |   |  HTTP   |   |   |          |    |
          |    +----------+<--|---|---------+   |   |          |    |
          |                   |   +-------------|-->+----------+    |
          |                   |                 |                   |
          |                   |                 |                   |
          v                   v                 v                   v
    ====================================================================
                                                             Redis pub/sub channel

### Using synctl with workers

If you want to use `synctl` to manage your synapse processes, you will need to create an an additional configuration file for the main synapse process. That configuration should look like this:

    worker_app: synapse.app.homeserver

Additionally, each worker app must be configured with the name of a "pid file", to which it will write its process ID when it starts. For example, for a synchrotron, you might write:

    worker_pid_file: /home/matrix/synapse/worker1.pid

Finally, to actually run your worker-based synapse, you must pass synctl the `-a` commandline option to tell it to operate on all the worker configurations found in the given directory, e.g.:

    synctl -a $CONFIG/workers start

Currently one should always restart all workers when restarting or upgrading synapse, unless you explicitly know it's safe not to. For instance, restarting synapse without restarting all the synchrotrons may result in broken typing notifications.

To manipulate a specific worker, you pass the -w option to synctl:

    synctl -w $CONFIG/workers/worker1.yaml restart

# Setting up Synapse with Workers and Systemd

This is a setup for managing synapse with systemd, including support for managing workers. It provides a `matrix-synapse` service for the master, as well as a `matrix-synapse-worker@` service template for any workers you require. Additionally, to group the required services, it sets up a `matrix-synapse.target`.

See the folder system for the systemd unit files.

The folder workers contains an example configuration for the `federation_reader` worker.

## Synapse configuration files

See the worker documentation for information on how to set up the configuration files and reverse-proxy correctly. Below is a sample `federation_reader` worker configuration file.

    worker_app: synapse.app.federation_reader
    worker_name: federation_reader1

    worker_replication_host: 127.0.0.1
    worker_replication_http_port: 9093

    worker_listeners:
        - type: http
          port: 8011
          resources:
              - names: [federation]

    worker_log_config: /etc/matrix-synapse/federation-reader-log.yaml

Systemd manages daemonization itself, so ensure that none of the configuration files set either `daemonize` or `worker_daemonize`.

The config files of all workers are expected to be located in `/etc/matrix-synapse/workers`. If you want to use a different location, edit the provided `*.service` files accordingly.

There is no need for a separate configuration file for the master process.

## Set up

1. Adjust synapse configuration files as above.
2. Copy the `*.service` and `*.target` files in system to `/etc/systemd/system`.
3. Run `systemctl daemon-reload` to tell systemd to load the new unit files.
4. Run `systemctl enable matrix-synapse.service`. This will configure the synapse master process to be started as part of the `matrix-synapse.target` target.
5. For each worker process to be enabled, run `systemctl enable matrix-synapse-worker@<worker_name>.service`. For each `<worker_name>`, there should be a corresponding configuration file. `/etc/matrix-synapse/workers/<worker_name>.yaml`.
6. Start all the synapse processes with `systemctl start matrix-synapse.target`.
7. Tell systemd to start synapse on boot with `systemctl enable matrix-synapse.target`.

## Usage

Once the services are correctly set up, you can use the following commands to manage your synapse installation:

    # Restart Synapse master and all workers
    systemctl restart matrix-synapse.target

    # Stop Synapse and all workers
    systemctl stop matrix-synapse.target

    # Restart the master alone
    systemctl start matrix-synapse.service

    # Restart a specific worker (eg. federation_reader); the master is
    # unaffected by this.
    systemctl restart matrix-synapse-worker@federation_reader.service

    # Add a new worker (assuming all configs are set up already)
    systemctl enable matrix-synapse-worker@federation_writer.service
    systemctl restart matrix-synapse.target

## Hardening

Optional: If further hardening is desired, the file `override-hardened.conf` may be copied from contrib/systemd/override-hardened.conf in this repository to the location `/etc/systemd/system/matrix-synapse.service.d/override-hardened.conf` (the directory may have to be created). It enables certain sandboxing features in systemd to further secure the synapse service. You may read the comments to understand what the override file is doing. The same file will need to be copied to `/etc/systemd/system/matrix-synapse-worker@.service.d/override-hardened-worker.conf` (this directory may also have to be created) in order to apply the same hardening options to any worker processes.

Once these files have been copied to their appropriate locations, simply reload systemd's manager config files and restart all Synapse services to apply the hardening options. They will automatically be applied at every restart as long as the override files are present at the specified locations.

    systemctl daemon-reload

    # Restart services
    systemctl restart matrix-synapse.target

In order to see their effect, you may run `systemd-analyze security matrix-synapse.service` before and after applying the hardening options to see the changes being applied at a glance.

# Administration

This section contains information on managing your Synapse homeserver. This includes:

- Managing users, rooms and media via the Admin API.
- Setting up metrics and monitoring to give you insight into your homeserver's health.
- Configuring structured logging.

# The Admin API

## Authenticate as a server admin

Many of the API calls in the admin api will require an `access_token` for a server admin. (Note that a server admin is distinct from a room admin.)

A user can be marked as a server admin by updating the database directly, e.g.:

    UPDATE users SET admin = 1 WHERE name = '@foo:bar.com';

A new server admin user can also be created using the `register_new_matrix_user` command. This is a script that is located in the `scripts/` directory, or possibly already on your `$PATH` depending on how Synapse was installed.

Finding your user's `access_token` is client-dependent, but will usually be shown in the client's settings.

## Making an Admin API request

Once you have your `access_token`, you will need to authenticate each request to an Admin API endpoint by providing the token as either a query parameter or a request header. To add it as a request header in cURL:

    curl --header "Authorization: Bearer <access_token>" <the_rest_of_your_API_request>

For more details on access tokens in Matrix, please refer to the complete matrix spec documentation.

# Account validity API

This API allows a server administrator to manage the validity of an account. To use it, you must enable the account validity feature (under `account_validity`) in Synapse's configuration.

## Renew account

This API extends the validity of an account by as much time as configured in the `period` parameter from the `account_validity` configuration.

The API is:

    POST /_synapse/admin/v1/account_validity/validity

with the following body:

    {
        "user_id": "<user ID for the account to renew>",
        "expiration_ts": 0,
        "enable_renewal_emails": true
    }

`expiration_ts` is an optional parameter and overrides the expiration date, which otherwise defaults to now + validity period.

`enable_renewal_emails` is also an optional parameter and enables/disables sending renewal emails to the user. Defaults to true.

The API returns with the new expiration date for this account, as a timestamp in milliseconds since epoch:

    {
        "expiration_ts": 0
    }

# Delete a local group

This API lets a server admin delete a local group. Doing so will kick all users out of the group so that their clients will correctly handle the group being deleted.

The API is:

    POST /_synapse/admin/v1/delete_group/<group_id>

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

# Show reported events

This API returns information about reported events.

The api is:

    GET /_synapse/admin/v1/event_reports?from=0&limit=10

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

It returns a JSON body like the following:

    {
        "event_reports": [
            {
                "event_id": "$bNUFCwGzWca1meCGkjp-zwslF-GfVcXukvRLI1_FaVY",
                "id": 2,
                "reason": "foo",
                "score": -100,
                "received_ts": 1570897107409,
                "canonical_alias": "#alias1:matrix.org",
                "room_id": "!ERAgBpSOcCCuTJqQPk:matrix.org",
                "name": "Matrix HQ",
                "sender": "@foobar:matrix.org",
                "user_id": "@foo:matrix.org"
            },
            {
                "event_id": "$3IcdZsDaN_En-S1DF4EMCy3v4gNRKeOJs8W5qTOKj4I",
                "id": 3,
                "reason": "bar",
                "score": -100,
                "received_ts": 1598889612059,
                "canonical_alias": "#alias2:matrix.org",
                "room_id": "!eGvUQuTCkHGVwNMOjv:matrix.org",
                "name": "Your room name here",
                "sender": "@foobar:matrix.org",
                "user_id": "@bar:matrix.org"
            }
        ],
        "next_token": 2,
        "total": 4
    }

To paginate, check for `next_token` and if present, call the endpoint again with `from` set to the value of `next_token`. This will return a new page.

If the endpoint does not return a `next_token` then there are no more reports to paginate through.

URL parameters:

- `limit`: integer - Is optional but is used for pagination, denoting the maximum number of items to return in this call. Defaults to `100`.
- `from`: integer - Is optional but used for pagination, denoting the offset in the returned results. This should be treated as an opaque value and not explicitly set to anything other than the return value of `next_token` from a previous call. Defaults to `0`.
- `dir`: string - Direction of event report order. Whether to fetch the most recent first (`b`) or the oldest first (`f`). Defaults to `b`.
- `user_id`: string - Is optional and filters to only return users with user IDs that contain this value. This is the user who reported the event and wrote the reason.
- `room_id`: string - Is optional and filters to only return rooms with room IDs that contain this value.

Response

The following fields are returned in the JSON response body:

- `id`: integer - ID of event report.
- `received_ts`: integer - The timestamp (in milliseconds since the unix epoch) when this report was sent.
- `room_id`: string - The ID of the room in which the event being reported is located.
- `name`: string - The name of the room.
- `event_id`: string - The ID of the reported event.
- `user_id`: string - This is the user who reported the event and wrote the reason.
- `reason`: string - Comment made by the `user_id` in this report. May be blank or `null`.
- `score`: integer - Content is reported based upon a negative score, where -100 is "most offensive" and 0 is "inoffensive". May be `null`.
- `sender`: string - This is the ID of the user who sent the original message/event that was reported.
- `canonical_alias`: string - The canonical alias of the room. `null` if the room does not have a canonical alias set.
- `next_token`: integer - Indication for pagination. See above.
- `total`: integer - Total number of event reports related to the query (`user_id` and `room_id`).

# Show details of a specific event report

This API returns information about a specific event report.

The api is:

    GET /_synapse/admin/v1/event_reports/<report_id>

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

It returns a JSON body like the following:

    {
        "event_id": "$bNUFCwGzWca1meCGkjp-zwslF-GfVcXukvRLI1_FaVY",
        "event_json": {
            "auth_events": [
                "$YK4arsKKcc0LRoe700pS8DSjOvUT4NDv0HfInlMFw2M",
                "$oggsNXxzPFRE3y53SUNd7nsj69-QzKv03a1RucHu-ws"
            ],
            "content": {
                "body": "matrix.org: This Week in Matrix",
                "format": "org.matrix.custom.html",
                "formatted_body": "<strong>matrix.org</strong>:<br><a href=\"https://matrix.org/blog/\"><strong>This Week in Matrix</strong></a>",
                "msgtype": "m.notice"
            },
            "depth": 546,
            "hashes": {
                "sha256": "xK1//xnmvHJIOvbgXlkI8eEqdvoMmihVDJ9J4SNlsAw"
            },
            "origin": "matrix.org",
            "origin_server_ts": 1592291711430,
            "prev_events": [
                "$YK4arsKKcc0LRoe700pS8DSjOvUT4NDv0HfInlMFw2M"
            ],
            "prev_state": [],
            "room_id": "!ERAgBpSOcCCuTJqQPk:matrix.org",
            "sender": "@foobar:matrix.org",
            "signatures": {
                "matrix.org": {
                    "ed25519:a_JaEG": "cs+OUKW/iHx5pEidbWxh0UiNNHwe46Ai9LwNz+Ah16aWDNszVIe2gaAcVZfvNsBhakQTew51tlKmL2kspXk/Dg"
                }
            },
            "type": "m.room.message",
            "unsigned": {
                "age_ts": 1592291711430,
            }
        },
        "id": <report_id>,
        "reason": "foo",
        "score": -100,
        "received_ts": 1570897107409,
        "canonical_alias": "#alias1:matrix.org",
        "room_id": "!ERAgBpSOcCCuTJqQPk:matrix.org",
        "name": "Matrix HQ",
        "sender": "@foobar:matrix.org",
        "user_id": "@foo:matrix.org"
    }

URL parameters:

- `report_id`: string - The ID of the event report.

Response

The following fields are returned in the JSON response body:

- `id`: integer - ID of event report.
- `received_ts`: integer - The timestamp (in milliseconds since the unix epoch) when this report was sent.
- `room_id`: string - The ID of the room in which the event being reported is located.
- `name`: string - The name of the room.
- `event_id`: string - The ID of the reported event.
- `user_id`: string - This is the user who reported the event and wrote the reason.
- `reason`: string - Comment made by the `user_id` in this report. May be blank.
- `score`: integer - Content is reported based upon a negative score, where -100 is "most offensive" and 0 is "inoffensive".
- `sender`: string - This is the ID of the user who sent the original message/event that was reported.
- `canonical_alias`: string - The canonical alias of the room. `null` if the room does not have a canonical alias set.
- `event_json`: object - Details of the original event that was reported.

# Contents

- Querying media
  - List all media in a room
  - List all media uploaded by a user
- Quarantine media
  - Quarantining media by ID
  - Remove media from quarantine by ID
  - Quarantining media in a room
  - Quarantining all media of a user
  - Protecting media from being quarantined
  - Unprotecting media from being quarantined
- Delete local media
  - Delete a specific local media
  - Delete local media by date or size
  - Delete media uploaded by a user
- Purge Remote Media API

# Querying media

These APIs allow extracting media information from the homeserver.

## List all media in a room

This API gets a list of known media in a room. However, it only shows media from unencrypted events or rooms.

The API is:

    GET /_synapse/admin/v1/room/<room_id>/media

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

The API returns a JSON body like the following:

    {
      "local": [
        "mxc://localhost/xwvutsrqponmlkjihgfedcba",
        "mxc://localhost/abcdefghijklmnopqrstuvwx"
      ],
      "remote": [
        "mxc://matrix.org/xwvutsrqponmlkjihgfedcba",
        "mxc://matrix.org/abcdefghijklmnopqrstuvwx"
      ]
    }

## List all media uploaded by a user

Listing all media that has been uploaded by a local user can be achieved through the use of the List media uploaded by a user Admin API.

# Quarantine media

Quarantining media means that it is marked as inaccessible by users. It applies to any local media, and any locally-cached copies of remote media.

The media file itself (and any thumbnails) is not deleted from the server.

## Quarantining media by ID

This API quarantines a single piece of local or remote media.

Request:

    POST /_synapse/admin/v1/media/quarantine/<server_name>/<media_id>

    {}

Where `server_name` is in the form of `example.org`, and `media_id` is in the form of `abcdefg12345...`.

Response:

    {}

## Remove media from quarantine by ID

This API removes a single piece of local or remote media from quarantine.

Request:

    POST /_synapse/admin/v1/media/unquarantine/<server_name>/<media_id>

    {}

Where `server_name` is in the form of `example.org`, and `media_id` is in the form of `abcdefg12345...`.

Response:

    {}

## Quarantining media in a room

This API quarantines all local and remote media in a room.

Request:

    POST /_synapse/admin/v1/room/<room_id>/media/quarantine

    {}

Where `room_id` is in the form of `!roomid12345:example.org`.

Response:

    {
      "num_quarantined": 10
    }

The following fields are returned in the JSON response body:

- `num_quarantined`: integer - The number of media items successfully quarantined

Note that there is a legacy endpoint, `POST /_synapse/admin/v1/quarantine_media/<room_id>`, that operates the same. However, it is deprecated and may be removed in a future release.

## Quarantining all media of a user

This API quarantines all local media that a local user has uploaded. That is to say, if you would like to quarantine media uploaded by a user on a remote homeserver, you should instead use one of the other APIs.

Request:

    POST /_synapse/admin/v1/user/<user_id>/media/quarantine

    {}

URL Parameters

- `user_id`: string - User ID in the form of `@bob:example.org`

Response:

    {
      "num_quarantined": 10
    }

The following fields are returned in the JSON response body:

- `num_quarantined`: integer - The number of media items successfully quarantined

## Protecting media from being quarantined

This API protects a single piece of local media from being quarantined using the above APIs. This is useful for sticker packs and other shared media which you do not want to get quarantined, especially when quarantining media in a room.

Request:

    POST /_synapse/admin/v1/media/protect/<media_id>

    {}

Where `media_id` is in the form of `abcdefg12345...`.

Response:

    {}

## Unprotecting media from being quarantined

This API reverts the protection of a media.

Request:

    POST /_synapse/admin/v1/media/unprotect/<media_id>

    {}

Where `media_id` is in the form of `abcdefg12345...`.

Response:

    {}

# Delete local media

This API deletes the local media from the disk of your own server. This includes any local thumbnails and copies of media downloaded from remote homeservers. This API will not affect media that has been uploaded to external media repositories (e.g https://github.com/turt2live/matrix-media-repo/). See also Purge Remote Media API.

## Delete a specific local media

Delete a specific `media_id`.

Request:

    DELETE /_synapse/admin/v1/media/<server_name>/<media_id>

    {}

URL Parameters

- `server_name`: string - The name of your local server (e.g `matrix.org`)
- `media_id`: string - The ID of the media (e.g `abcdefghijklmnopqrstuvwx`)

Response:

    {
      "deleted_media": [
        "abcdefghijklmnopqrstuvwx"
      ],
      "total": 1
    }

The following fields are returned in the JSON response body:

- `deleted_media`: an array of strings - List of deleted `media_id`
- `total`: integer - Total number of deleted `media_id`

## Delete local media by date or size

Request:

    POST /_synapse/admin/v1/media/<server_name>/delete?before_ts=<before_ts>

    {}

URL Parameters

- `server_name`: string - The name of your local server (e.g `matrix.org`).
- `before_ts`: string representing a positive integer - Unix timestamp in milliseconds. Files that were last used before this timestamp will be deleted. It is the timestamp of last access, not the timestamp when the file was created.
- `size_gt`: Optional - string representing a positive integer - Size of the media in bytes. Files that are larger will be deleted. Defaults to `0`.
- `keep_profiles`: Optional - string representing a boolean - Switch to also delete files that are still used in image data (e.g user profile, room avatar). If `false` these files will be deleted. Defaults to `true`.

Response:

    {
      "deleted_media": [
        "abcdefghijklmnopqrstuvwx",
        "abcdefghijklmnopqrstuvwz"
      ],
      "total": 2
    }

The following fields are returned in the JSON response body:

- `deleted_media`: an array of strings - List of deleted `media_id`
- `total`: integer - Total number of deleted `media_id`

## Delete media uploaded by a user

You can find details of how to delete multiple media uploaded by a user in User Admin API.

# Purge Remote Media API

The purge remote media API allows server admins to purge old cached remote media.

The API is:

    POST /_synapse/admin/v1/purge_media_cache?before_ts=<unix_timestamp_in_ms>

    {}

URL Parameters

- `unix_timestamp_in_ms`: string representing a positive integer - Unix timestamp in milliseconds. All cached media that was last accessed before this timestamp will be removed.

Response:

    {
      "deleted": 10
    }

The following fields are returned in the JSON response body:

- `deleted`: integer - The number of media items successfully deleted

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

If the user re-requests purged remote media, synapse will re-request the media from the originating server.

# Purge History API

The purge history API allows server admins to purge historic events from their database, reclaiming disk space.

Depending on the amount of history being purged a call to the API may take several minutes or longer. During this period users will not be able to paginate further back in the room from the point being purged from.

Note that Synapse requires at least one message in each room, so it will never delete the last message in a room.

The API is:

    POST /_synapse/admin/v1/purge_history/<room_id>[/<event_id>]

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

By default, events sent by local users are not deleted, as they may represent the only copies of this content in existence. (Events sent by remote users are deleted.)

Room state data (such as joins, leaves, topic) is always preserved.

To delete local message events as well, set `delete_local_events` in the body:

    {
       "delete_local_events": true
    }

The caller must specify the point in the room to purge up to. This can be specified by including an event_id in the URI, or by setting a `purge_up_to_event_id` or `purge_up_to_ts` in the request body. If an event id is given, that event (and others at the same graph depth) will be retained. If `purge_up_to_ts` is given, it should be a timestamp since the unix epoch, in milliseconds.

The API starts the purge running, and returns immediately with a JSON body with a purge id:

    {
        "purge_id": "<opaque id>"
    }

## Purge status query

It is possible to poll for updates on recent purges with a second API;

    GET /_synapse/admin/v1/purge_history_status/<purge_id>

Again, you will need to authenticate by providing an `access_token` for a server admin.

This API returns a JSON body like the following:

    {
        "status": "active"
    }

The status will be one of `active`, `complete`, or `failed`.

## Reclaim disk space (Postgres)

To reclaim the disk space and return it to the operating system, you need to run `VACUUM FULL;` on the database.

https://www.postgresql.org/docs/current/sql-vacuum.html

# Shared-Secret Registration

This API allows for the creation of users in an administrative and non-interactive way. This is generally used for bootstrapping a Synapse instance with administrator accounts.

To authenticate yourself to the server, you will need both the shared secret (`registration_shared_secret` in the homeserver configuration), and a one-time nonce. If the registration shared secret is not configured, this API is not enabled.

To fetch the nonce, you need to request one from the API:

    > GET /_synapse/admin/v1/register

    < {"nonce": "thisisanonce"}

Once you have the nonce, you can make a `POST` to the same URL with a JSON body containing the nonce, username, password, whether they are an admin (optional, False by default), and a HMAC digest of the content. Also you can set the displayname (optional, `username` by default).

As an example:

    > POST /_synapse/admin/v1/register
    > {
       "nonce": "thisisanonce",
       "username": "pepper_roni",
       "displayname": "Pepper Roni",
       "password": "pizza",
       "admin": true,
       "mac": "mac_digest_here"
      }

    < {
       "access_token": "token_here",
       "user_id": "@pepper_roni:localhost",
       "home_server": "test",
       "device_id": "device_id_here"
      }

The MAC is the hex digest output of the HMAC-SHA1 algorithm, with the key being the shared secret and the content being the nonce, user, password, either the string "admin" or "notadmin", and optionally the user_type each separated by NULs. For an example of generation in Python:

    import hmac, hashlib

    def generate_mac(nonce, user, password, admin=False, user_type=None):

        mac = hmac.new(
          key=shared_secret,
          digestmod=hashlib.sha1,
        )

        mac.update(nonce.encode('utf8'))
        mac.update(b"\x00")
        mac.update(user.encode('utf8'))
        mac.update(b"\x00")
        mac.update(password.encode('utf8'))
        mac.update(b"\x00")
        mac.update(b"admin" if admin else b"notadmin")
        if user_type:
            mac.update(b"\x00")
            mac.update(user_type.encode('utf8'))

        return mac.hexdigest()

# Registration Tokens

This API allows you to manage tokens which can be used to authenticate registration requests, as proposed in MSC3231. To use it, you will need to enable the `registration_requires_token` config option, and authenticate by providing an `access_token` for a server admin: see Admin API. Note that this API is still experimental; not all clients may support it yet.

## Registration token objects

Most endpoints make use of JSON objects that contain details about tokens. These objects have the following fields:

- `token`: The token which can be used to authenticate registration.
- `uses_allowed`: The number of times the token can be used to complete a registration before it becomes invalid.
- `pending`: The number of pending uses the token has. When someone uses the token to authenticate themselves, the pending counter is incremented so that the token is not used more than the permitted number of times. When the person completes registration the pending counter is decremented, and the completed counter is incremented.
- `completed`: The number of times the token has been used to successfully complete a registration.
- `expiry_time`: The latest time the token is valid. Given as the number of milliseconds since 1970-01-01 00:00:00 UTC (the start of the Unix epoch). To convert this into a human-readable form you can remove the milliseconds and use the `date` command. For example, `date -d '@1625394937'`.

## List all tokens

Lists all tokens and details about them. If the request is successful, the top level JSON object will have a `registration_tokens` key which is an array of registration token objects.

    GET /_synapse/admin/v1/registration_tokens

Optional query parameters:

- `valid`: `true` or `false`. If `true`, only valid tokens are returned. If `false`, only tokens that have expired or have had all uses exhausted are returned. If omitted, all tokens are returned regardless of validity.

Example:

    GET /_synapse/admin/v1/registration_tokens

    200 OK

    {
        "registration_tokens": [
            {
                "token": "abcd",
                "uses_allowed": 3,
                "pending": 0,
                "completed": 1,
                "expiry_time": null
            },
            {
                "token": "pqrs",
                "uses_allowed": 2,
                "pending": 1,
                "completed": 1,
                "expiry_time": null
            },
            {
                "token": "wxyz",
                "uses_allowed": null,
                "pending": 0,
                "completed": 9,
                "expiry_time": 1625394937000    // 2021-07-04 10:35:37 UTC
            }
        ]
    }

Example using the `valid` query parameter:

    GET /_synapse/admin/v1/registration_tokens?valid=false

    200 OK

    {
        "registration_tokens": [
            {
                "token": "pqrs",
                "uses_allowed": 2,
                "pending": 1,
                "completed": 1,
                "expiry_time": null
            },
            {
                "token": "wxyz",
                "uses_allowed": null,
                "pending": 0,
                "completed": 9,
                "expiry_time": 1625394937000    // 2021-07-04 10:35:37 UTC
            }
        ]
    }

## Get one token

Get details about a single token. If the request is successful, the response body will be a registration token object.

    GET /_synapse/admin/v1/registration_tokens/<token>

Path parameters:

- `token`: The registration token to return details of.

Example:

    GET /_synapse/admin/v1/registration_tokens/abcd

    200 OK

    {
        "token": "abcd",
        "uses_allowed": 3,
        "pending": 0,
        "completed": 1,
        "expiry_time": null
    }

## Create token

Create a new registration token. If the request is successful, the newly created token will be returned as a registration token object in the response body.

    POST /_synapse/admin/v1/registration_tokens/new

The request body must be a JSON object and can contain the following fields:

- `token`: The registration token. A string of no more than 64 characters that consists only of characters matched by the regex `[A-Za-z0-9._~-]`. Default: randomly generated.
- `uses_allowed`: The integer number of times the token can be used to complete a registration before it becomes invalid. Default: `null` (unlimited uses).
- `expiry_time`: The latest time the token is valid. Given as the number of milliseconds since 1970-01-01 00:00:00 UTC (the start of the Unix epoch). You could use, for example, `date '+%s000' -d 'tomorrow'`. Default: `null` (token does not expire).
- `length`: The length of the token randomly generated if `token` is not specified. Must be between 1 and 64 inclusive. Default: `16`.

If a field is omitted the default is used.

Example using defaults:

    POST /_synapse/admin/v1/registration_tokens/new

    {}

    200 OK

    {
        "token": "0M-9jbkf2t_Tgiw1",
        "uses_allowed": null,
        "pending": 0,
        "completed": 0,
        "expiry_time": null
    }

Example specifying some fields:

    POST /_synapse/admin/v1/registration_tokens/new

    {
        "token": "defg",
        "uses_allowed": 1
    }

    200 OK

    {
        "token": "defg",
        "uses_allowed": 1,
        "pending": 0,
        "completed": 0,
        "expiry_time": null
    }

## Update token

Update the number of allowed uses or expiry time of a token. If the request is successful, the updated token will be returned as a registration token object in the response body.

    PUT /_synapse/admin/v1/registration_tokens/<token>

Path parameters:

- `token`: The registration token to update.

The request body must be a JSON object and can contain the following fields:

- `uses_allowed`: The integer number of times the token can be used to complete a registration before it becomes invalid. By setting `uses_allowed` to `0` the token can be easily made invalid without deleting it. If `null` the token will have an unlimited number of uses.
- `expiry_time`: The latest time the token is valid. Given as the number of milliseconds since 1970-01-01 00:00:00 UTC (the start of the Unix epoch). If `null` the token will not expire.

If a field is omitted its value is not modified.

Example:

    PUT /_synapse/admin/v1/registration_tokens/defg

    {
        "expiry_time": 4781243146000    // 2121-07-06 11:05:46 UTC
    }

    200 OK

    {
        "token": "defg",
        "uses_allowed": 1,
        "pending": 0,
        "completed": 0,
        "expiry_time": 4781243146000
    }

## Delete token

Delete a registration token. If the request is successful, the response body will be an empty JSON object.

    DELETE /_synapse/admin/v1/registration_tokens/<token>

Path parameters:

- `token`: The registration token to delete.

Example:

    DELETE /_synapse/admin/v1/registration_tokens/wxyz

    200 OK

    {}

## Errors

If a request fails a "standard error response" will be returned as defined in the Matrix Client-Server API specification.

For example, if the token specified in a path parameter does not exist a `404 Not Found` error will be returned.

    GET /_synapse/admin/v1/registration_tokens/1234

    404 Not Found

    {
        "errcode": "M_NOT_FOUND",
        "error": "No such registration token: 1234"
    }

# Edit Room Membership API

This API allows an administrator to join an user account with a given `user_id` to a room with a given `room_id_or_alias`. You can only modify the membership of local users. The server administrator must be in the room and have permission to invite users.

## Parameters

The following parameters are available:

- `user_id` - Fully qualified user: for example, `@user:server.com`.
- `room_id_or_alias` - The room identifier or alias to join: for example, `!636q39766251:server.com`.

## Usage

    POST /_synapse/admin/v1/join/<room_id_or_alias>

    {
      "user_id": "@user:server.com"
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

Response:

    {
      "room_id": "!636q39766251:server.com"
    }

# Contents

- List Room API
- Room Details API
- Room Members API
- Room State API
- Delete Room API
  - Undoing room shutdowns
- Make Room Admin API
- Forward Extremities Admin API
- Event Context API

# List Room API

The List Room admin API allows server admins to get a list of rooms on their server. There are various parameters available that allow for filtering and sorting the returned list. This API supports pagination.

Parameters

The following query parameters are available:

- `from` - Offset in the returned list. Defaults to `0`.
- `limit` - Maximum amount of rooms to return. Defaults to `100`.
- `order_by` - The method in which to sort the returned list of rooms. Valid values are:
  - `alphabetical` - Same as `name`. This is deprecated.
  - `size` - Same as `joined_members`. This is deprecated.
  - `name` - Rooms are ordered alphabetically by room name. This is the default.
  - `canonical_alias` - Rooms are ordered alphabetically by main alias address of the room.
  - `joined_members` - Rooms are ordered by the number of members. Largest to smallest.
  - `joined_local_members` - Rooms are ordered by the number of local members. Largest to smallest.
  - `version` - Rooms are ordered by room version. Largest to smallest.
  - `creator` - Rooms are ordered alphabetically by creator of the room.
  - `encryption` - Rooms are ordered alphabetically by the end-to-end encryption algorithm.
  - `federatable` - Rooms are ordered by whether the room is federatable.
  - `public` - Rooms are ordered by visibility in room list.
  - `join_rules` - Rooms are ordered alphabetically by join rules of the room.
  - `guest_access` - Rooms are ordered alphabetically by guest access option of the room.
  - `history_visibility` - Rooms are ordered alphabetically by visibility of history of the room.
  - `state_events` - Rooms are ordered by number of state events. Largest to smallest.
- `dir` - Direction of room order. Either `f` for forwards or `b` for backwards. Setting this value to `b` will reverse the above sort order. Defaults to `f`.
- `search_term` - Filter rooms by their room name. Search term can be contained in any part of the room name. Defaults to no filtering.

Response

The following fields are possible in the JSON response body:

- `rooms` - An array of objects, each containing information about a room.
  - Room objects contain the following fields:
    - `room_id` - The ID of the room.
    - `name` - The name of the room.
    - `canonical_alias` - The canonical (main) alias address of the room.
    - `joined_members` - How many users are currently in the room.
    - `joined_local_members` - How many local users are currently in the room.
    - `version` - The version of the room as a string.
    - `creator` - The `user_id` of the room creator.
    - `encryption` - Algorithm of end-to-end encryption of messages. Is `null` if encryption is not active.
    - `federatable` - Whether users on other servers can join this room.
    - `public` - Whether the room is visible in room directory.
    - `join_rules` - The type of rules used for users wishing to join this room. One of: ["public", "knock", "invite", "private"].
    - `guest_access` - Whether guests can join the room. One of: ["can_join", "forbidden"].
    - `history_visibility` - Who can see the room history. One of: ["invited", "joined", "shared", "world_readable"].
    - `state_events` - Total number of state_events of a room. Complexity of the room.
- `offset` - The current pagination offset in rooms. This parameter should be used instead of `next_token` for room offset as `next_token` is not intended to be parsed.
- `total_rooms` - The total number of rooms this query can return. Using this and `offset`, you have enough information to know the current progression through the list.
- `next_batch` - If this field is present, we know that there are potentially more rooms on the server that did not all fit into this response. We can use `next_batch` to get the "next page" of results. To do so, simply repeat your request, setting the `from` parameter to the value of `next_batch`.
- `prev_batch` - If this field is present, it is possible to paginate backwards. Use `prev_batch` for the `from` value in the next request to get the "previous page" of results.

The API is:

A standard request with no filtering:

    GET /_synapse/admin/v1/rooms

A response body like the following is returned:

    {
      "rooms": [
        {
          "room_id": "!OGEhHVWSdvArJzumhm:matrix.org",
          "name": "Matrix HQ",
          "canonical_alias": "#matrix:matrix.org",
          "joined_members": 8326,
          "joined_local_members": 2,
          "version": "1",
          "creator": "@foo:matrix.org",
          "encryption": null,
          "federatable": true,
          "public": true,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 93534
        },
        ... (8 hidden items) ...
        {
          "room_id": "!xYvNcQPhnkrdUmYczI:matrix.org",
          "name": "This Week In Matrix (TWIM)",
          "canonical_alias": "#twim:matrix.org",
          "joined_members": 314,
          "joined_local_members": 20,
          "version": "4",
          "creator": "@foo:matrix.org",
          "encryption": "m.megolm.v1.aes-sha2",
          "federatable": true,
          "public": false,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 8345
        }
      ],
      "offset": 0,
      "total_rooms": 10
    }

Filtering by room name:

    GET /_synapse/admin/v1/rooms?search_term=TWIM

A response body like the following is returned:

    {
      "rooms": [
        {
          "room_id": "!xYvNcQPhnkrdUmYczI:matrix.org",
          "name": "This Week In Matrix (TWIM)",
          "canonical_alias": "#twim:matrix.org",
          "joined_members": 314,
          "joined_local_members": 20,
          "version": "4",
          "creator": "@foo:matrix.org",
          "encryption": "m.megolm.v1.aes-sha2",
          "federatable": true,
          "public": false,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 8
        }
      ],
      "offset": 0,
      "total_rooms": 1
    }

Paginating through a list of rooms:

    GET /_synapse/admin/v1/rooms?order_by=size

A response body like the following is returned:

    {
      "rooms": [
        {
          "room_id": "!OGEhHVWSdvArJzumhm:matrix.org",
          "name": "Matrix HQ",
          "canonical_alias": "#matrix:matrix.org",
          "joined_members": 8326,
          "joined_local_members": 2,
          "version": "1",
          "creator": "@foo:matrix.org",
          "encryption": null,
          "federatable": true,
          "public": true,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 93534
        },
        ... (98 hidden items) ...
        {
          "room_id": "!xYvNcQPhnkrdUmYczI:matrix.org",
          "name": "This Week In Matrix (TWIM)",
          "canonical_alias": "#twim:matrix.org",
          "joined_members": 314,
          "joined_local_members": 20,
          "version": "4",
          "creator": "@foo:matrix.org",
          "encryption": "m.megolm.v1.aes-sha2",
          "federatable": true,
          "public": false,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 8345
        }
      ],
      "offset": 0,
      "total_rooms": 150
      "next_token": 100
    }

The presence of the `next_token` parameter tells us that there are more rooms than returned in this request, and we need to make another request to get them. To get the next batch of room results, we repeat our request, setting the `from` parameter to the value of `next_token`.

    GET /_synapse/admin/v1/rooms?order_by=size&from=100

A response body like the following is returned:

    {
      "rooms": [
        {
          "room_id": "!mscvqgqpHYjBGDxNym:matrix.org",
          "name": "Music Theory",
          "canonical_alias": "#musictheory:matrix.org",
          "joined_members": 127,
          "joined_local_members": 2,
          "version": "1",
          "creator": "@foo:matrix.org",
          "encryption": null,
          "federatable": true,
          "public": true,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 93534
        },
        ... (48 hidden items) ...
        {
          "room_id": "!twcBhHVdZlQWuuxBhN:termina.org.uk",
          "name": "weechat-matrix",
          "canonical_alias": "#weechat-matrix:termina.org.uk",
          "joined_members": 137,
          "joined_local_members": 20,
          "version": "4",
          "creator": "@foo:termina.org.uk",
          "encryption": null,
          "federatable": true,
          "public": true,
          "join_rules": "invite",
          "guest_access": null,
          "history_visibility": "shared",
          "state_events": 8345
        }
      ],
      "offset": 100,
      "prev_batch": 0,
      "total_rooms": 150
    }

Once the `next_token` parameter is no longer present, we know we've reached the end of the list.

# Room Details API

The Room Details admin API allows server admins to get all details of a room.

The following fields are possible in the JSON response body:

- `room_id` - The ID of the room.
- `name` - The name of the room.
- `topic` - The topic of the room.
- `avatar` - The `mxc` URI to the avatar of the room.
- `canonical_alias` - The canonical (main) alias address of the room.
- `joined_members` - How many users are currently in the room.
- `joined_local_members` - How many local users are currently in the room.
- `joined_local_devices` - How many local devices are currently in the room.
- `version` - The version of the room as a string.
- `creator` - The `user_id` of the room creator.
- `encryption` - Algorithm of end-to-end encryption of messages. Is `null` if encryption is not active.
- `federatable` - Whether users on other servers can join this room.
- `public` - Whether the room is visible in room directory.
- `join_rules` - The type of rules used for users wishing to join this room. One of: ["public", "knock", "invite", "private"].
- `guest_access` - Whether guests can join the room. One of: ["can_join", "forbidden"].
- `history_visibility` - Who can see the room history. One of: ["invited", "joined", "shared", "world_readable"].
- `state_events` - Total number of state_events of a room. Complexity of the room.

The API is:

    GET /_synapse/admin/v1/rooms/<room_id>

A response body like the following is returned:

    {
      "room_id": "!mscvqgqpHYjBGDxNym:matrix.org",
      "name": "Music Theory",
      "avatar": "mxc://matrix.org/AQDaVFlbkQoErdOgqWRgiGSV",
      "topic": "Theory, Composition, Notation, Analysis",
      "canonical_alias": "#musictheory:matrix.org",
      "joined_members": 127,
      "joined_local_members": 2,
      "joined_local_devices": 2,
      "version": "1",
      "creator": "@foo:matrix.org",
      "encryption": null,
      "federatable": true,
      "public": true,
      "join_rules": "invite",
      "guest_access": null,
      "history_visibility": "shared",
      "state_events": 93534
    }

# Room Members API

The Room Members admin API allows server admins to get a list of all members of a room.

The response includes the following fields:

- `members` - A list of all the members that are present in the room, represented by their ids.
- `total` - Total number of members in the room.

The API is:

    GET /_synapse/admin/v1/rooms/<room_id>/members

A response body like the following is returned:

    {
      "members": [
        "@foo:matrix.org",
        "@bar:matrix.org",
        "@foobar:matrix.org"
      ],
      "total": 3
    }

# Room State API

The Room State admin API allows server admins to get a list of all state events in a room.

The response includes the following fields:

- `state` - The current state of the room at the time of request.

The API is:

    GET /_synapse/admin/v1/rooms/<room_id>/state

A response body like the following is returned:

    {
      "state": [
        {"type": "m.room.create", "state_key": "", "etc": true},
        {"type": "m.room.power_levels", "state_key": "", "etc": true},
        {"type": "m.room.name", "state_key": "", "etc": true}
      ]
    }

# Delete Room API

The Delete Room admin API allows server admins to remove rooms from server and block these rooms.

Shuts down a room. Moves all local users and room aliases automatically to a new room if `new_room_user_id` is set. Otherwise local users only leave the room without any information.

The new room will be created with the user specified by the `new_room_user_id` parameter as room administrator and will contain a message explaining what happened. Users invited to the new room will have power level `-10` by default, and thus be unable to speak.

If `block` is `True` it prevents new joins to the old room.

This API will remove all trace of the old room from your database after removing all local users. If `purge` is `true` (the default), all traces of the old room will be removed from your database after removing all local users. If you do not want this to happen, set `purge` to `false`. Depending on the amount of history being purged a call to the API may take several minutes or longer.

The local server will only have the power to move local user and room aliases to the new room. Users on other servers will be unaffected.

The API is:

    DELETE /_synapse/admin/v1/rooms/<room_id>

with a body of:

    {
        "new_room_user_id": "@someuser:example.com",
        "room_name": "Content Violation Notification",
        "message": "Bad Room has been shutdown due to content violations on this server. Please review our Terms of Service.",
        "block": true,
        "purge": true
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

A response body like the following is returned:

    {
        "kicked_users": [
            "@foobar:example.com"
        ],
        "failed_to_kick_users": [],
        "local_aliases": [
            "#badroom:example.com",
            "#evilsaloon:example.com"
        ],
        "new_room_id": "!newroomid:example.com"
    }

Parameters

The following parameters should be set in the URL:

- `room_id` - The ID of the room.

The following JSON body parameters are available:

- `new_room_user_id` - Optional. If set, a new room will be created with this user ID as the creator and admin, and all users in the old room will be moved into that room. If not set, no new room will be created and the users will just be removed from the old room. The user ID must be on the local server, but does not necessarily have to belong to a registered user.
- `room_name` - Optional. A string representing the name of the room that new users will be invited to. Defaults to `Content Violation Notification`
- `message` - Optional. A string containing the first message that will be sent as `new_room_user_id` in the new room. Ideally this will clearly convey why the original room was shut down. Defaults to `Sharing illegal content on this server is not permitted and rooms in violation will be blocked.`
- `block` - Optional. If set to `true`, this room will be added to a blocking list, preventing future attempts to join the room. Defaults to `false`.
- `purge` - Optional. If set to `true`, it will remove all traces of the room from your database. Defaults to `true`.
- `force_purge` - Optional, and ignored unless `purge` is `true`. If set to `true`, it will force a purge to go ahead even if there are local users still in the room. Do not use this unless a regular `purge` operation fails, as it could leave those users' clients in a confused state.

The JSON body must not be empty. The body must be at least `{}`.

Response

The following fields are returned in the JSON response body:

- `kicked_users` - An array of users (`user_id`) that were kicked.
- `failed_to_kick_users` - An array of users (`user_id`) that that were not kicked.
- `local_aliases` - An array of strings representing the local aliases that were migrated from the old room to the new.
- `new_room_id` - A string representing the room ID of the new room.

## Undoing room deletions

Note: This guide may be outdated by the time you read it. By nature of room deletions being performed at the database level, the structure can and does change without notice.

First, it's important to understand that a room deletion is very destructive. Undoing a deletion is not as simple as pretending it never happened - work has to be done to move forward instead of resetting the past. In fact, in some cases it might not be possible to recover at all:

- If the room was invite-only, your users will need to be re-invited.
- If the room no longer has any members at all, it'll be impossible to rejoin.
- The first user to rejoin will have to do so via an alias on a different server (or receive an invite from a user on a different server).

With all that being said, if you still want to try and recover the room:

1. If the room was `block`ed, you must unblock it on your server. This can be accomplished as follows:

   1. For safety reasons, shut down Synapse.
   2. In the database, run `DELETE FROM blocked_rooms WHERE room_id = '!example:example.org';`
      - For caution: it's recommended to run this in a transaction: `BEGIN; DELETE ...;`, verify you got 1 result, then `COMMIT;`.
      - The room ID is the same one supplied to the delete room API, not the Content Violation room.
   3. Restart Synapse.

   This step is unnecessary if `block` was not set.

2. Any room aliases on your server that pointed to the deleted room may have been deleted, or redirected to the Content Violation room. These will need to be restored manually.

3. Users on your server that were in the deleted room will have been kicked from the room. Consider whether you want to update their membership (possibly via the Edit Room Membership API) or let them handle rejoining themselves.

4. If `new_room_user_id` was given, a 'Content Violation' will have been created. Consider whether you want to delete that roomm.

## Deprecated endpoint

The previous deprecated API will be removed in a future release, it was:

    POST /_synapse/admin/v1/rooms/<room_id>/delete

It behaves the same way than the current endpoint except the path and the method.

# Make Room Admin API

Grants another user the highest power available to a local user who is in the room. If the user is not in the room, and it is not publicly joinable, then invite the user.

By default the server admin (the caller) is granted power, but another user can optionally be specified, e.g.:

    POST /_synapse/admin/v1/rooms/<room_id_or_alias>/make_room_admin
    {
        "user_id": "@foo:example.com"
    }

# Forward Extremities Admin API

Enables querying and deleting forward extremities from rooms. When a lot of forward extremities accumulate in a room, performance can become degraded. For details, see #1760.

## Check for forward extremities

To check the status of forward extremities for a room:

    GET /_synapse/admin/v1/rooms/<room_id_or_alias>/forward_extremities

A response as follows will be returned:

    {
      "count": 1,
      "results": [
        {
          "event_id": "$M5SP266vsnxctfwFgFLNceaCo3ujhRtg_NiiHabcdefgh",
          "state_group": 439,
          "depth": 123,
          "received_ts": 1611263016761
        }
      ]
    }

## Deleting forward extremities

WARNING: Please ensure you know what you're doing and have read the related issue #1760. Under no situations should this API be executed as an automated maintenance task!

If a room has lots of forward extremities, the extra can be deleted as follows:

    DELETE /_synapse/admin/v1/rooms/<room_id_or_alias>/forward_extremities

A response as follows will be returned, indicating the amount of forward extremities that were deleted.

    {
      "deleted": 1
    }

# Event Context API

This API lets a client find the context of an event. This is designed primarily to investigate abuse reports.

    GET /_synapse/admin/v1/rooms/<room_id>/context/<event_id>

This API mimmicks GET /_matrix/client/r0/rooms/{roomId}/context/{eventId}. Please refer to the link for all details on parameters and reseponse.

Example response:

    {
      "end": "t29-57_2_0_2",
      "events_after": [
        {
          "content": {
            "body": "This is an example text message",
            "msgtype": "m.text",
            "format": "org.matrix.custom.html",
            "formatted_body": "<b>This is an example text message</b>"
          },
          "type": "m.room.message",
          "event_id": "$143273582443PhrSn:example.org",
          "room_id": "!636q39766251:example.com",
          "sender": "@example:example.org",
          "origin_server_ts": 1432735824653,
          "unsigned": {
            "age": 1234
          }
        }
      ],
      "event": {
        "content": {
          "body": "filename.jpg",
          "info": {
            "h": 398,
            "w": 394,
            "mimetype": "image/jpeg",
            "size": 31037
          },
          "url": "mxc://example.org/JWEIFJgwEIhweiWJE",
          "msgtype": "m.image"
        },
        "type": "m.room.message",
        "event_id": "$f3h4d129462ha:example.com",
        "room_id": "!636q39766251:example.com",
        "sender": "@example:example.org",
        "origin_server_ts": 1432735824653,
        "unsigned": {
          "age": 1234
        }
      },
      "events_before": [
        {
          "content": {
            "body": "something-important.doc",
            "filename": "something-important.doc",
            "info": {
              "mimetype": "application/msword",
              "size": 46144
            },
            "msgtype": "m.file",
            "url": "mxc://example.org/FHyPlCeYUSFFxlgbQYZmoEoe"
          },
          "type": "m.room.message",
          "event_id": "$143273582443PhrSn:example.org",
          "room_id": "!636q39766251:example.com",
          "sender": "@example:example.org",
          "origin_server_ts": 1432735824653,
          "unsigned": {
            "age": 1234
          }
        }
      ],
      "start": "t27-54_2_0_2",
      "state": [
        {
          "content": {
            "creator": "@example:example.org",
            "room_version": "1",
            "m.federate": true,
            "predecessor": {
              "event_id": "$something:example.org",
              "room_id": "!oldroom:example.org"
            }
          },
          "type": "m.room.create",
          "event_id": "$143273582443PhrSn:example.org",
          "room_id": "!636q39766251:example.com",
          "sender": "@example:example.org",
          "origin_server_ts": 1432735824653,
          "unsigned": {
            "age": 1234
          },
          "state_key": ""
        },
        {
          "content": {
            "membership": "join",
            "avatar_url": "mxc://example.org/SEsfnsuifSDFSSEF",
            "displayname": "Alice Margatroid"
          },
          "type": "m.room.member",
          "event_id": "$143273582443PhrSn:example.org",
          "room_id": "!636q39766251:example.com",
          "sender": "@example:example.org",
          "origin_server_ts": 1432735824653,
          "unsigned": {
            "age": 1234
          },
          "state_key": "@alice:example.org"
        }
      ]
    }

# Server Notices

The API to send notices is as follows:

    POST /_synapse/admin/v1/send_server_notice

or:

    PUT /_synapse/admin/v1/send_server_notice/{txnId}

You will need to authenticate with an access token for an admin user.

When using the `PUT` form, retransmissions with the same transaction ID will be ignored in the same way as with `PUT /_matrix/client/r0/rooms/{roomId}/send/{eventType}/{txnId}`.

The request body should look something like the following:

    {
        "user_id": "@target_user:server_name",
        "content": {
            "msgtype": "m.text",
            "body": "This is my message"
        }
    }

You can optionally include the following additional parameters:

- `type`: the type of event. Defaults to `m.room.message`.
- `state_key`: Setting this will result in a state event being sent.

Once the notice has been sent, the API will return the following response:

    {
        "event_id": "<event_id>"
    }

Note that server notices must be enabled in `homeserver.yaml` before this API can be used. See the server notices documentation for more information.

# Users' media usage statistics

Returns information about all local media usage of users. Gives the possibility to filter them by time and user.

The API is:

    GET /_synapse/admin/v1/statistics/users/media

To use it, you will need to authenticate by providing an `access_token` for a server admin: see Admin API.

A response body like the following is returned:

    {
      "users": [
        {
          "displayname": "foo_user_0",
          "media_count": 2,
          "media_length": 134,
          "user_id": "@foo_user_0:test"
        },
        {
          "displayname": "foo_user_1",
          "media_count": 2,
          "media_length": 134,
          "user_id": "@foo_user_1:test"
        }
      ],
      "next_token": 3,
      "total": 10
    }

To paginate, check for `next_token` and if present, call the endpoint again with `from` set to the value of `next_token`. This will return a new page.

If the endpoint does not return a `next_token` then there are no more reports to paginate through.

Parameters

The following parameters should be set in the URL:

- `limit`: string representing a positive integer - Is optional but is used for pagination, denoting the maximum number of items to return in this call. Defaults to `100`.
- `from`: string representing a positive integer - Is optional but used for pagination, denoting the offset in the returned results. This should be treated as an opaque value and not explicitly set to anything other than the return value of `next_token` from a previous call. Defaults to `0`.
- `order_by` - string - The method in which to sort the returned list of users. Valid values are:
  - `user_id` - Users are ordered alphabetically by `user_id`. This is the default.
  - `displayname` - Users are ordered alphabetically by `displayname`.
  - `media_length` - Users are ordered by the total size of uploaded media in bytes. Smallest to largest.
  - `media_count` - Users are ordered by number of uploaded media. Smallest to largest.
- `from_ts` - string representing a positive integer - Considers only files created at this timestamp or later. Unix timestamp in ms.
- `until_ts` - string representing a positive integer - Considers only files created at this timestamp or earlier. Unix timestamp in ms.
- `search_term` - string - Filter users by their user ID localpart or displayname. The search term can be found in any part of the string. Defaults to no filtering.
- `dir` - string - Direction of order. Either `f` for forwards or `b` for backwards. Setting this value to `b` will reverse the above sort order. Defaults to `f`.

Response

The following fields are returned in the JSON response body:

- `users` - An array of objects, each containing information about the user and their local media. Objects contain the following fields:
  - `displayname` - string - Displayname of this user.
  - `media_count` - integer - Number of uploaded media by this user.
  - `media_length` - integer - Size of uploaded media in bytes by this user.
  - `user_id` - string - Fully-qualified user ID (ex. `@user:server.com`).
- `next_token` - integer - Opaque value used for pagination. See above.
- `total` - integer - Total number of users after filtering.

# User Admin API

## Query User Account

This API returns information about a specific user account.

The api is:

    GET /_synapse/admin/v2/users/<user_id>

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

It returns a JSON body like the following:

    {
        "displayname": "User",
        "threepids": [
            {
                "medium": "email",
                "address": "<user_mail_1>",
                "added_at": 1586458409743,
                "validated_at": 1586458409743
            },
            {
                "medium": "email",
                "address": "<user_mail_2>",
                "added_at": 1586458409743,
                "validated_at": 1586458409743
            }
        ],
        "avatar_url": "<avatar_url>",
        "admin": 0,
        "deactivated": 0,
        "shadow_banned": 0,
        "password_hash": "$2b$12$p9B4GkqYdRTPGD",
        "creation_ts": 1560432506,
        "appservice_id": null,
        "consent_server_notice_sent": null,
        "consent_version": null,
        "external_ids": [
            {
                "auth_provider": "<provider1>",
                "external_id": "<user_id_provider_1>"
            },
            {
                "auth_provider": "<provider2>",
                "external_id": "<user_id_provider_2>"
            }
        ],
        "user_type": null
    }

URL parameters:

- `user_id`: fully-qualified user id: for example, `@user:server.com`.

## Create or modify Account

This API allows an administrator to create or modify a user account with a specific `user_id`.

This api is:

    PUT /_synapse/admin/v2/users/<user_id>

with a body of:

    {
        "password": "user_password",
        "displayname": "User",
        "threepids": [
            {
                "medium": "email",
                "address": "<user_mail_1>"
            },
            {
                "medium": "email",
                "address": "<user_mail_2>"
            }
        ],
        "external_ids": [
            {
                "auth_provider": "<provider1>",
                "external_id": "<user_id_provider_1>"
            },
            {
                "auth_provider": "<provider2>",
                "external_id": "<user_id_provider_2>"
            }
        ],
        "avatar_url": "<avatar_url>",
        "admin": false,
        "deactivated": false,
        "user_type": null
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

Returns HTTP status code:

- `201` - When a new user object was created.
- `200` - When a user was modified.

URL parameters:

- `user_id`: fully-qualified user id: for example, `@user:server.com`.

Body parameters:

- `password` - string, optional. If provided, the user's password is updated and all devices are logged out.
- `displayname` - string, optional, defaults to the value of `user_id`.
- `threepids` - array, optional, allows setting the third-party IDs (email, msisdn)
  - `medium` - string. Kind of third-party ID, either `email` or `msisdn`.
  - `address` - string. Value of third-party ID. belonging to a user.
- `external_ids` - array, optional. Allow setting the identifier of the external identity provider for SSO (Single sign-on). Details in Sample Configuration File section `sso` and `oidc_providers`.
  - `auth_provider` - string. ID of the external identity provider. Value of `idp_id` in homeserver configuration.
  - `external_id` - string, user ID in the external identity provider.
- `avatar_url` - string, optional, must be a MXC URI.
- `admin` - bool, optional, defaults to `false`.
- `deactivated` - bool, optional. If unspecified, deactivation state will be left unchanged on existing accounts and set to `false` for new accounts. A user cannot be erased by deactivating with this API. For details on deactivating users see Deactivate Account.
- `user_type` - string or null, optional. If provided, the user type will be adjusted. If `null` given, the user type will be cleared. Other allowed options are: `bot` and `support`.

If the user already exists then optional parameters default to the current value.

In order to re-activate an account `deactivated` must be set to `false`. If users do not login via single-sign-on, a new `password` must be provided.

## List Accounts

This API returns all local user accounts. By default, the response is ordered by ascending user ID.

    GET /_synapse/admin/v2/users?from=0&limit=10&guests=false

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
        "users": [
            {
                "name": "<user_id1>",
                "is_guest": 0,
                "admin": 0,
                "user_type": null,
                "deactivated": 0,
                "shadow_banned": 0,
                "displayname": "<User One>",
                "avatar_url": null,
                "creation_ts": 1560432668000
            }, {
                "name": "<user_id2>",
                "is_guest": 0,
                "admin": 1,
                "user_type": null,
                "deactivated": 0,
                "shadow_banned": 0,
                "displayname": "<User Two>",
                "avatar_url": "<avatar_url>",
                "creation_ts": 1561550621000
            }
        ],
        "next_token": "100",
        "total": 200
    }

To paginate, check for `next_token` and if present, call the endpoint again with `from` set to the value of `next_token`. This will return a new page.

If the endpoint does not return a `next_token` then there are no more users to paginate through.

Parameters

The following parameters should be set in the URL:

- `user_id` - Is optional and filters to only return users with user IDs that contain this value. This parameter is ignored when using the `name` parameter.

- `name` - Is optional and filters to only return users with user ID localparts or displaynames that contain this value.

- `guests` - string representing a bool - Is optional and if `false` will exclude guest users. Defaults to `true` to include guest users.

- `deactivated` - string representing a bool - Is optional and if `true` will include deactivated users. Defaults to `false` to exclude deactivated users.

- `limit` - string representing a positive integer - Is optional but is used for pagination, denoting the maximum number of items to return in this call. Defaults to `100`.

- `from` - string representing a positive integer - Is optional but used for pagination, denoting the offset in the returned results. This should be treated as an opaque value and not explicitly set to anything other than the return value of `next_token` from a previous call. Defaults to `0`.

- `order_by` - The method by which to sort the returned list of users. If the ordered field has duplicates, the second order is always by ascending `name`, which guarantees a stable ordering. Valid values are:

  - `name` - Users are ordered alphabetically by `name`. This is the default.
  - `is_guest` - Users are ordered by `is_guest` status.
  - `admin` - Users are ordered by `admin` status.
  - `user_type` - Users are ordered alphabetically by `user_type`.
  - `deactivated` - Users are ordered by `deactivated` status.
  - `shadow_banned` - Users are ordered by `shadow_banned` status.
  - `displayname` - Users are ordered alphabetically by `displayname`.
  - `avatar_url` - Users are ordered alphabetically by avatar URL.
  - `creation_ts` - Users are ordered by when the users was created in ms.

- `dir` - Direction of media order. Either `f` for forwards or `b` for backwards. Setting this value to `b` will reverse the above sort order. Defaults to `f`.

Caution. The database only has indexes on the columns `name` and `creation_ts`. This means that if a different sort order is used (`is_guest`, `admin`, `user_type`, `deactivated`, `shadow_banned`, `avatar_url` or `displayname`), this can cause a large load on the database, especially for large environments.

Response

The following fields are returned in the JSON response body:

- `users` - An array of objects, each containing information about an user. User objects contain the following fields:

  - `name` - string - Fully-qualified user ID (ex. `@user:server.com`).
  - `is_guest` - bool - Status if that user is a guest account.
  - `admin` - bool - Status if that user is a server administrator.
  - `user_type` - string - Type of the user. Normal users are type `None`. This allows user type specific behaviour. There are also types `support` and `bot`.
  - `deactivated` - bool - Status if that user has been marked as deactivated.
  - `shadow_banned` - bool - Status if that user has been marked as shadow banned.
  - `displayname` - string - The user's display name if they have set one.
  - `avatar_url` - string - The user's avatar URL if they have set one.
  - `creation_ts` - integer - The user's creation timestamp in ms.

- `next_token`: string representing a positive integer - Indication for pagination. See above.

- `total` - integer - Total number of media.

## Query current sessions for a user

This API returns information about the active sessions for a specific user.

The endpoints are:

    GET /_synapse/admin/v1/whois/<user_id>

and:

    GET /_matrix/client/r0/admin/whois/<userId>

See also: Client Server API Whois.

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

It returns a JSON body like the following:

    {
        "user_id": "<user_id>",
        "devices": {
            "": {
                "sessions": [
                    {
                        "connections": [
                            {
                                "ip": "1.2.3.4",
                                "last_seen": 1417222374433,
                                "user_agent": "Mozilla/5.0 ..."
                            },
                            {
                                "ip": "1.2.3.10",
                                "last_seen": 1417222374500,
                                "user_agent": "Dalvik/2.1.0 ..."
                            }
                        ]
                    }
                ]
            }
        }
    }

`last_seen` is measured in milliseconds since the Unix epoch.

## Deactivate Account

This API deactivates an account. It removes active access tokens, resets the password, and deletes third-party IDs (to prevent the user requesting a password reset).

It can also mark the user as GDPR-erased. This means messages sent by the user will still be visible by anyone that was in the room when these messages were sent, but hidden from users joining the room afterwards.

The api is:

    POST /_synapse/admin/v1/deactivate/<user_id>

with a body of:

    {
        "erase": true
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

The erase parameter is optional and defaults to `false`. An empty body may be passed for backwards compatibility.

The following actions are performed when deactivating an user:

- Try to unpind 3PIDs from the identity server
- Remove all 3PIDs from the homeserver
- Delete all devices and E2EE keys
- Delete all access tokens
- Delete all pushers
- Delete the password hash
- Removal from all rooms the user is a member of
- Remove the user from the user directory
- Reject all pending invites
- Remove all account validity information related to the user

The following additional actions are performed during deactivation if `erase` is set to `true`:

- Remove the user's display name
- Remove the user's avatar URL
- Mark the user as erased

The following actions are NOT performed. The list may be incomplete.

- Remove mappings of SSO IDs
- Delete media uploaded by user (included avatar images)
- Delete sent and received messages
- Delete E2E cross-signing keys
- Remove the user's creation (registration) timestamp
- Remove rate limit overrides
- Remove from monthly active users

## Reset password

Changes the password of another user. This will automatically log the user out of all their devices.

The api is:

    POST /_synapse/admin/v1/reset_password/<user_id>

with a body of:

    {
       "new_password": "<secret>",
       "logout_devices": true
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

The parameter `new_password` is required. The parameter `logout_devices` is optional and defaults to `true`.

## Get whether a user is a server administrator or not

The api is:

    GET /_synapse/admin/v1/users/<user_id>/admin

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
        "admin": true
    }

## Change whether a user is a server administrator or not

Note that you cannot demote yourself.

The api is:

    PUT /_synapse/admin/v1/users/<user_id>/admin

with a body of:

    {
        "admin": true
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

## List room memberships of a user

Gets a list of all `room_id` that a specific `user_id` is member.

The API is:

    GET /_synapse/admin/v1/users/<user_id>/joined_rooms

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

        {
            "joined_rooms": [
                "!DuGcnbhHGaSZQoNQR:matrix.org",
                "!ZtSaPCawyWtxfWiIy:matrix.org"
            ],
            "total": 2
        }

The server returns the list of rooms of which the user and the server are member. If the user is local, all the rooms of which the user is member are returned.

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.

Response

The following fields are returned in the JSON response body:

- `joined_rooms` - An array of `room_id`.
- `total` - Number of rooms.

## User media

### List media uploaded by a user

Gets a list of all local media that a specific `user_id` has created. By default, the response is ordered by descending creation date and ascending media ID. The newest media is on top. You can change the order with parameters `order_by` and `dir`.

The API is:

    GET /_synapse/admin/v1/users/<user_id>/media

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "media": [
        {
          "created_ts": 100400,
          "last_access_ts": null,
          "media_id": "qXhyRzulkwLsNHTbpHreuEgo",
          "media_length": 67,
          "media_type": "image/png",
          "quarantined_by": null,
          "safe_from_quarantine": false,
          "upload_name": "test1.png"
        },
        {
          "created_ts": 200400,
          "last_access_ts": null,
          "media_id": "FHfiSnzoINDatrXHQIXBtahw",
          "media_length": 67,
          "media_type": "image/png",
          "quarantined_by": null,
          "safe_from_quarantine": false,
          "upload_name": "test2.png"
        }
      ],
      "next_token": 3,
      "total": 2
    }

To paginate, check for `next_token` and if present, call the endpoint again with `from` set to the value of `next_token`. This will return a new page.

If the endpoint does not return a `next_token` then there are no more reports to paginate through.

Parameters

The following parameters should be set in the URL:

- `user_id` - string - fully qualified: for example, `@user:server.com`.

- `limit`: string representing a positive integer - Is optional but is used for pagination, denoting the maximum number of items to return in this call. Defaults to `100`.

- `from`: string representing a positive integer - Is optional but used for pagination, denoting the offset in the returned results. This should be treated as an opaque value and not explicitly set to anything other than the return value of `next_token` from a previous call. Defaults to `0`.

- `order_by` - The method by which to sort the returned list of media. If the ordered field has duplicates, the second order is always by ascending `media_id`, which guarantees a stable ordering. Valid values are:

  - `media_id` - Media are ordered alphabetically by `media_id`.
  - `upload_name` - Media are ordered alphabetically by name the media was uploaded with.
  - `created_ts` - Media are ordered by when the content was uploaded in ms. Smallest to largest. This is the default.
  - `last_access_ts` - Media are ordered by when the content was last accessed in ms. Smallest to largest.
  - `media_length` - Media are ordered by length of the media in bytes. Smallest to largest.
  - `media_type` - Media are ordered alphabetically by MIME-type.
  - `quarantined_by` - Media are ordered alphabetically by the user ID that initiated the quarantine request for this media.
  - `safe_from_quarantine` - Media are ordered by the status if this media is safe from quarantining.

- `dir` - Direction of media order. Either `f` for forwards or `b` for backwards. Setting this value to `b` will reverse the above sort order. Defaults to `f`.

If neither `order_by` nor `dir` is set, the default order is newest media on top (corresponds to `order_by` = `created_ts` and `dir` = `b`).

Caution. The database only has indexes on the columns `media_id`, `user_id` and `created_ts`. This means that if a different sort order is used (`upload_name`, `last_access_ts`, `media_length`, `media_type`, `quarantined_by` or `safe_from_quarantine`), this can cause a large load on the database, especially for large environments.

Response

The following fields are returned in the JSON response body:

- `media` - An array of objects, each containing information about a media. Media objects contain the following fields:
  - `created_ts` - integer - Timestamp when the content was uploaded in ms.
  - `last_access_ts` - integer - Timestamp when the content was last accessed in ms.
  - `media_id` - string - The id used to refer to the media.
  - `media_length` - integer - Length of the media in bytes.
  - `media_type` - string - The MIME-type of the media.
  - `quarantined_by` - string - The user ID that initiated the quarantine request for this media.
  - `safe_from_quarantine` - bool - Status if this media is safe from quarantining.
  - `upload_name` - string - The name the media was uploaded with.
- `next_token`: integer - Indication for pagination. See above.
- `total` - integer - Total number of media.

### Delete media uploaded by a user

This API deletes the local media from the disk of your own server that a specific `user_id` has created. This includes any local thumbnails.

This API will not affect media that has been uploaded to external media repositories (e.g https://github.com/turt2live/matrix-media-repo/).

By default, the API deletes media ordered by descending creation date and ascending media ID. The newest media is deleted first. You can change the order with parameters `order_by` and `dir`. If no `limit` is set the API deletes `100` files per request.

The API is:

    DELETE /_synapse/admin/v1/users/<user_id>/media

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "deleted_media": [
        "abcdefghijklmnopqrstuvwx"
      ],
      "total": 1
    }

The following fields are returned in the JSON response body:

- `deleted_media`: an array of strings - List of deleted `media_id`
- `total`: integer - Total number of deleted `media_id`

Note: There is no `next_token`. This is not useful for deleting media, because after deleting media the remaining media have a new order.

Parameters

This API has the same parameters as List media uploaded by a user. With the parameters you can for example limit the number of files to delete at once or delete largest/smallest or newest/oldest files first.

## Login as a user

Get an access token that can be used to authenticate as that user. Useful for when admins wish to do actions on behalf of a user.

The API is:

    POST /_synapse/admin/v1/users/<user_id>/login
    {}

An optional `valid_until_ms` field can be specified in the request body as an integer timestamp that specifies when the token should expire. By default tokens do not expire.

A response body like the following is returned:

    {
        "access_token": "<opaque_access_token_string>"
    }

This API does not generate a new device for the user, and so will not appear their `/devices` list, and in general the target user should not be able to tell they have been logged in as.

To expire the token call the standard `/logout` API with the token.

Note: The token will expire if the admin user calls `/logout/all` from any of their devices, but the token will not expire if the target user does the same.

## User devices

### List all devices

Gets information about all devices for a specific `user_id`.

The API is:

    GET /_synapse/admin/v2/users/<user_id>/devices

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "devices": [
        {
          "device_id": "QBUAZIFURK",
          "display_name": "android",
          "last_seen_ip": "1.2.3.4",
          "last_seen_ts": 1474491775024,
          "user_id": "<user_id>"
        },
        {
          "device_id": "AUIECTSRND",
          "display_name": "ios",
          "last_seen_ip": "1.2.3.5",
          "last_seen_ts": 1474491775025,
          "user_id": "<user_id>"
        }
      ],
      "total": 2
    }

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.

Response

The following fields are returned in the JSON response body:

- `devices` - An array of objects, each containing information about a device. Device objects contain the following fields:

  - `device_id` - Identifier of device.
  - `display_name` - Display name set by the user for this device. Absent if no name has been set.
  - `last_seen_ip` - The IP address where this device was last seen. (May be a few minutes out of date, for efficiency reasons).
  - `last_seen_ts` - The timestamp (in milliseconds since the unix epoch) when this devices was last seen. (May be a few minutes out of date, for efficiency reasons).
  - `user_id` - Owner of device.

- `total` - Total number of user's devices.

### Delete multiple devices

Deletes the given devices for a specific `user_id`, and invalidates any access token associated with them.

The API is:

    POST /_synapse/admin/v2/users/<user_id>/delete_devices

    {
      "devices": [
        "QBUAZIFURK",
        "AUIECTSRND"
      ],
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

An empty JSON dict is returned.

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.

The following fields are required in the JSON request body:

- `devices` - The list of device IDs to delete.

### Show a device

Gets information on a single device, by `device_id` for a specific `user_id`.

The API is:

    GET /_synapse/admin/v2/users/<user_id>/devices/<device_id>

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "device_id": "<device_id>",
      "display_name": "android",
      "last_seen_ip": "1.2.3.4",
      "last_seen_ts": 1474491775024,
      "user_id": "<user_id>"
    }

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.
- `device_id` - The device to retrieve.

Response

The following fields are returned in the JSON response body:

- `device_id` - Identifier of device.
- `display_name` - Display name set by the user for this device. Absent if no name has been set.
- `last_seen_ip` - The IP address where this device was last seen. (May be a few minutes out of date, for efficiency reasons).
- `last_seen_ts` - The timestamp (in milliseconds since the unix epoch) when this devices was last seen. (May be a few minutes out of date, for efficiency reasons).
- `user_id` - Owner of device.

### Update a device

Updates the metadata on the given `device_id` for a specific `user_id`.

The API is:

    PUT /_synapse/admin/v2/users/<user_id>/devices/<device_id>

    {
      "display_name": "My other phone"
    }

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

An empty JSON dict is returned.

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.
- `device_id` - The device to update.

The following fields are required in the JSON request body:

- `display_name` - The new display name for this device. If not given, the display name is unchanged.

### Delete a device

Deletes the given `device_id` for a specific `user_id`, and invalidates any access token associated with it.

The API is:

    DELETE /_synapse/admin/v2/users/<user_id>/devices/<device_id>

    {}

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

An empty JSON dict is returned.

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.
- `device_id` - The device to delete.

## List all pushers

Gets information about all pushers for a specific `user_id`.

The API is:

    GET /_synapse/admin/v1/users/<user_id>/pushers

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "pushers": [
        {
          "app_display_name":"HTTP Push Notifications",
          "app_id":"m.http",
          "data": {
            "url":"example.com"
          },
          "device_display_name":"pushy push",
          "kind":"http",
          "lang":"None",
          "profile_tag":"",
          "pushkey":"a@example.com"
        }
      ],
      "total": 1
    }

Parameters

The following parameters should be set in the URL:

- `user_id` - fully qualified: for example, `@user:server.com`.

Response

The following fields are returned in the JSON response body:

- `pushers` - An array containing the current pushers for the user

  - `app_display_name` - string - A string that will allow the user to identify what application owns this pusher.

  - `app_id` - string - This is a reverse-DNS style identifier for the application. Max length, 64 chars.

  - `data` - A dictionary of information for the pusher implementation itself.

    - `url` - string - Required if `kind` is `http`. The URL to use to send notifications to.

    - `format` - string - The format to use when sending notifications to the Push Gateway.

  - `device_display_name` - string - A string that will allow the user to identify what device owns this pusher.

  - `profile_tag` - string - This string determines which set of device specific rules this pusher executes.

  - `kind` - string - The kind of pusher. "http" is a pusher that sends HTTP pokes.

  - `lang` - string - The preferred language for receiving notifications (e.g. 'en' or 'en-US')

  - `profile_tag` - string - This string determines which set of device specific rules this pusher executes.

  - `pushkey` - string - This is a unique identifier for this pusher. Max length, 512 bytes.

- `total` - integer - Number of pushers.

See also the Client-Server API Spec on pushers.

## Shadow-banning users

Shadow-banning is a useful tool for moderating malicious or egregiously abusive users. A shadow-banned users receives successful responses to their client-server API requests, but the events are not propagated into rooms. This can be an effective tool as it (hopefully) takes longer for the user to realise they are being moderated before pivoting to another account.

Shadow-banning a user should be used as a tool of last resort and may lead to confusing or broken behaviour for the client. A shadow-banned user will not receive any notification and it is generally more appropriate to ban or kick abusive users. A shadow-banned user will be unable to contact anyone on the server.

The API is:

    POST /_synapse/admin/v1/users/<user_id>/shadow_ban

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

An empty JSON dict is returned.

Parameters

The following parameters should be set in the URL:

- `user_id` - The fully qualified MXID: for example, `@user:server.com`. The user must be local.

## Override ratelimiting for users

This API allows to override or disable ratelimiting for a specific user. There are specific APIs to set, get and delete a ratelimit.

### Get status of ratelimit

The API is:

    GET /_synapse/admin/v1/users/<user_id>/override_ratelimit

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "messages_per_second": 0,
      "burst_count": 0
    }

Parameters

The following parameters should be set in the URL:

- `user_id` - The fully qualified MXID: for example, `@user:server.com`. The user must be local.

Response

The following fields are returned in the JSON response body:

- `messages_per_second` - integer - The number of actions that can be performed in a second. `0` mean that ratelimiting is disabled for this user.
- `burst_count` - integer - How many actions that can be performed before being limited.

If no custom ratelimit is set, an empty JSON dict is returned.

    {}

### Set ratelimit

The API is:

    POST /_synapse/admin/v1/users/<user_id>/override_ratelimit

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

A response body like the following is returned:

    {
      "messages_per_second": 0,
      "burst_count": 0
    }

Parameters

The following parameters should be set in the URL:

- `user_id` - The fully qualified MXID: for example, `@user:server.com`. The user must be local.

Body parameters:

- `messages_per_second` - positive integer, optional. The number of actions that can be performed in a second. Defaults to `0`.
- `burst_count` - positive integer, optional. How many actions that can be performed before being limited. Defaults to `0`.

To disable users' ratelimit set both values to `0`.

Response

The following fields are returned in the JSON response body:

- `messages_per_second` - integer - The number of actions that can be performed in a second.
- `burst_count` - integer - How many actions that can be performed before being limited.

### Delete ratelimit

The API is:

    DELETE /_synapse/admin/v1/users/<user_id>/override_ratelimit

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

An empty JSON dict is returned.

    {}

Parameters

The following parameters should be set in the URL:

- `user_id` - The fully qualified MXID: for example, `@user:server.com`. The user must be local.

### Check username availability

Checks to see if a username is available, and valid, for the server. See the client-server API for more information.

This endpoint will work even if registration is disabled on the server, unlike `/_matrix/client/r0/register/available`.

The API is:

    POST /_synapse/admin/v1/username_availabile?username=$localpart

The request and response format is the same as the /_matrix/client/r0/register/available API.

To use it, you will need to authenticate by providing an `access_token` for a server admin: Admin API

# Version API

This API returns the running Synapse version and the Python version on which Synapse is being run. This is useful when a Synapse instance is behind a proxy that does not forward the 'Server' header (which also contains Synapse version information).

The api is:

    GET /_synapse/admin/v1/server_version

It returns a JSON body like the following:

    {
        "server_version": "0.99.2rc1 (b=develop, abcdef123)",
        "python_version": "3.6.8"
    }

# Using the synapse manhole

The "manhole" allows server administrators to access a Python shell on a running Synapse installation. This is a very powerful mechanism for administration and debugging.

Security Warning

Note that this will give administrative access to synapse to all users with shell access to the server. It should therefore not be enabled in environments where untrusted users have shell access.

## Configuring the manhole

To enable it, first uncomment the `manhole` listener configuration in `homeserver.yaml`. The configuration is slightly different if you're using docker.

#### Docker config

If you are using Docker, set `bind_addresses` to `['0.0.0.0']` as shown:

    listeners:
      - port: 9000
        bind_addresses: ['0.0.0.0']
        type: manhole

When using `docker run` to start the server, you will then need to change the command to the following to include the `manhole` port forwarding. The `-p 127.0.0.1:9000:9000` below is important: it ensures that access to the `manhole` is only possible for local users.

    docker run -d --name synapse \
        --mount type=volume,src=synapse-data,dst=/data \
        -p 8008:8008 \
        -p 127.0.0.1:9000:9000 \
        matrixdotorg/synapse:latest

#### Native config

If you are not using docker, set `bind_addresses` to `['::1', '127.0.0.1']` as shown. The `bind_addresses` in the example below is important: it ensures that access to the `manhole` is only possible for local users).

    listeners:
      - port: 9000
        bind_addresses: ['::1', '127.0.0.1']
        type: manhole

### Security settings

The following config options are available:

- `username` - The username for the manhole (defaults to `matrix`)
- `password` - The password for the manhole (defaults to `rabbithole`)
- `ssh_priv_key` - The path to a private SSH key (defaults to a hardcoded value)
- `ssh_pub_key` - The path to a public SSH key (defaults to a hardcoded value)

For example:

    manhole_settings:
      username: manhole
      password: mypassword
      ssh_priv_key: "/home/synapse/manhole_keys/id_rsa"
      ssh_pub_key: "/home/synapse/manhole_keys/id_rsa.pub"

## Accessing synapse manhole

Then restart synapse, and point an ssh client at port 9000 on localhost, using the username and password configured in `homeserver.yaml` - with the default configuration, this would be:

    ssh -p9000 matrix@localhost

Then enter the password when prompted (the default is `rabbithole`).

This gives a Python REPL in which `hs` gives access to the `synapse.server.HomeServer` object - which in turn gives access to many other parts of the process.

Note that, prior to Synapse 1.41, any call which returns a coroutine will need to be wrapped in `ensureDeferred`.

As a simple example, retrieving an event from the database:

    >>> from twisted.internet import defer
    >>> defer.ensureDeferred(hs.get_datastore().get_event('$1416420717069yeQaw:matrix.org'))
    <Deferred at 0x7ff253fc6998 current result: <FrozenEvent event_id='$1416420717069yeQaw:matrix.org', type='m.room.create', state_key=''>>

# How to monitor Synapse metrics using Prometheus

1. Install Prometheus:

   Follow instructions at http://prometheus.io/docs/introduction/install/

2. Enable Synapse metrics:

   There are two methods of enabling metrics in Synapse.

   The first serves the metrics as a part of the usual web server and can be enabled by adding the "metrics" resource to the existing listener as such:

         resources:
           - names:
             - client
             - metrics

   This provides a simple way of adding metrics to your Synapse installation, and serves under `/_synapse/metrics`. If you do not wish your metrics be publicly exposed, you will need to either filter it out at your load balancer, or use the second method.

   The second method runs the metrics server on a different port, in a different thread to Synapse. This can make it more resilient to heavy load meaning metrics cannot be retrieved, and can be exposed to just internal networks easier. The served metrics are available over HTTP only, and will be available at `/_synapse/metrics`.

   Add a new listener to homeserver.yaml:

         listeners:
           - type: metrics
             port: 9000
             bind_addresses:
               - '0.0.0.0'

   For both options, you will need to ensure that `enable_metrics` is set to `True`.

3. Restart Synapse.

4. Add a Prometheus target for Synapse.

   It needs to set the `metrics_path` to a non-default value (under `scrape_configs`):

         - job_name: "synapse"
           scrape_interval: 15s
           metrics_path: "/_synapse/metrics"
           static_configs:
             - targets: ["my.server.here:port"]

   where `my.server.here` is the IP address of Synapse, and `port` is the listener port configured with the `metrics` resource.

   If your prometheus is older than 1.5.2, you will need to replace `static_configs` in the above with `target_groups`.

5. Restart Prometheus.

6. Consider using the grafana dashboard and required recording rules

## Monitoring workers

To monitor a Synapse installation using workers, every worker needs to be monitored independently, in addition to the main homeserver process. This is because workers don't send their metrics to the main homeserver process, but expose them directly (if they are configured to do so).

To allow collecting metrics from a worker, you need to add a `metrics` listener to its configuration, by adding the following under `worker_listeners`:

      - type: metrics
        bind_address: ''
        port: 9101

The `bind_address` and `port` parameters should be set so that the resulting listener can be reached by prometheus, and they don't clash with an existing worker. With this example, the worker's metrics would then be available on `http://127.0.0.1:9101`.

Example Prometheus target for Synapse with workers:

      - job_name: "synapse"
        scrape_interval: 15s
        metrics_path: "/_synapse/metrics"
        static_configs:
          - targets: ["my.server.here:port"]
            labels:
              instance: "my.server"
              job: "master"
              index: 1
          - targets: ["my.workerserver.here:port"]
            labels:
              instance: "my.server"
              job: "generic_worker"
              index: 1
          - targets: ["my.workerserver.here:port"]
            labels:
              instance: "my.server"
              job: "generic_worker"
              index: 2
          - targets: ["my.workerserver.here:port"]
            labels:
              instance: "my.server"
              job: "media_repository"
              index: 1

Labels (`instance`, `job`, `index`) can be defined as anything. The labels are used to group graphs in grafana.

## Renaming of metrics & deprecation of old names in 1.2

Synapse 1.2 updates the Prometheus metrics to match the naming convention of the upstream `prometheus_client`. The old names are considered deprecated and will be removed in a future version of Synapse.

New Name | Old Name
--- | ---
python_gc_objects_collected_total | python_gc_objects_collected
python_gc_objects_uncollectable_total | python_gc_objects_uncollectable
python_gc_collections_total | python_gc_collections
process_cpu_seconds_total | process_cpu_seconds
synapse_federation_client_sent_transactions_total | synapse_federation_client_sent_transactions
synapse_federation_client_events_processed_total | synapse_federation_client_events_processed
synapse_event_processing_loop_count_total | synapse_event_processing_loop_count
synapse_event_processing_loop_room_count_total | synapse_event_processing_loop_room_count
synapse_util_metrics_block_count_total | synapse_util_metrics_block_count
synapse_util_metrics_block_time_seconds_total | synapse_util_metrics_block_time_seconds
synapse_util_metrics_block_ru_utime_seconds_total | synapse_util_metrics_block_ru_utime_seconds
synapse_util_metrics_block_ru_stime_seconds_total | synapse_util_metrics_block_ru_stime_seconds
synapse_util_metrics_block_db_txn_count_total | synapse_util_metrics_block_db_txn_count
synapse_util_metrics_block_db_txn_duration_seconds_total | synapse_util_metrics_block_db_txn_duration_seconds
synapse_util_metrics_block_db_sched_duration_seconds_total | synapse_util_metrics_block_db_sched_duration_seconds
synapse_background_process_start_count_total | synapse_background_process_start_count
synapse_background_process_ru_utime_seconds_total | synapse_background_process_ru_utime_seconds
synapse_background_process_ru_stime_seconds_total | synapse_background_process_ru_stime_seconds
synapse_background_process_db_txn_count_total | synapse_background_process_db_txn_count
synapse_background_process_db_txn_duration_seconds_total | synapse_background_process_db_txn_duration_seconds
synapse_background_process_db_sched_duration_seconds_total | synapse_background_process_db_sched_duration_seconds
synapse_storage_events_persisted_events_total | synapse_storage_events_persisted_events
synapse_storage_events_persisted_events_sep_total | synapse_storage_events_persisted_events_sep
synapse_storage_events_state_delta_total | synapse_storage_events_state_delta
synapse_storage_events_state_delta_single_event_total | synapse_storage_events_state_delta_single_event
synapse_storage_events_state_delta_reuse_delta_total | synapse_storage_events_state_delta_reuse_delta
synapse_federation_server_received_pdus_total | synapse_federation_server_received_pdus
synapse_federation_server_received_edus_total | synapse_federation_server_received_edus
synapse_handler_presence_notified_presence_total | synapse_handler_presence_notified_presence
synapse_handler_presence_federation_presence_out_total | synapse_handler_presence_federation_presence_out
synapse_handler_presence_presence_updates_total | synapse_handler_presence_presence_updates
synapse_handler_presence_timers_fired_total | synapse_handler_presence_timers_fired
synapse_handler_presence_federation_presence_total | synapse_handler_presence_federation_presence
synapse_handler_presence_bump_active_time_total | synapse_handler_presence_bump_active_time
synapse_federation_client_sent_edus_total | synapse_federation_client_sent_edus
synapse_federation_client_sent_pdu_destinations_count_total | synapse_federation_client_sent_pdu_destinations:count
synapse_federation_client_sent_pdu_destinations_total | synapse_federation_client_sent_pdu_destinations:total
synapse_handlers_appservice_events_processed_total | synapse_handlers_appservice_events_processed
synapse_notifier_notified_events_total | synapse_notifier_notified_events
synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total | synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter
synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter_total | synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter
synapse_http_httppusher_http_pushes_processed_total | synapse_http_httppusher_http_pushes_processed
synapse_http_httppusher_http_pushes_failed_total | synapse_http_httppusher_http_pushes_failed
synapse_http_httppusher_badge_updates_processed_total | synapse_http_httppusher_badge_updates_processed
synapse_http_httppusher_badge_updates_failed_total | synapse_http_httppusher_badge_updates_failed

## Removal of deprecated metrics & time based counters becoming histograms in 0.31.0

The duplicated metrics deprecated in Synapse 0.27.0 have been removed.

All time duration-based metrics have been changed to be seconds. This affects:

msec -> sec metrics
python_gc_time
python_twisted_reactor_tick_time
synapse_storage_query_time
synapse_storage_schedule_time
synapse_storage_transaction_time

Several metrics have been changed to be histograms, which sort entries into buckets and allow better analysis. The following metrics are now histograms:

Altered metrics
python_gc_time
python_twisted_reactor_pending_calls
python_twisted_reactor_tick_time
synapse_http_server_response_time_seconds
synapse_storage_query_time
synapse_storage_schedule_time
synapse_storage_transaction_time

## Block and response metrics renamed for 0.27.0

Synapse 0.27.0 begins the process of rationalising the duplicate `*:count` metrics reported for the resource tracking for code blocks and HTTP requests.

At the same time, the corresponding `*:total` metrics are being renamed, as the `:total` suffix no longer makes sense in the absence of a corresponding `:count` metric.

To enable a graceful migration path, this release just adds new names for the metrics being renamed. A future release will remove the old ones.

The following table shows the new metrics, and the old metrics which they are replacing.

New name | Old name
--- | ---
synapse_util_metrics_block_count | synapse_util_metrics_block_timer:count
synapse_util_metrics_block_count | synapse_util_metrics_block_ru_utime:count
synapse_util_metrics_block_count | synapse_util_metrics_block_ru_stime:count
synapse_util_metrics_block_count | synapse_util_metrics_block_db_txn_count:count
synapse_util_metrics_block_count | synapse_util_metrics_block_db_txn_duration:count
synapse_util_metrics_block_time_seconds | synapse_util_metrics_block_timer:total
synapse_util_metrics_block_ru_utime_seconds | synapse_util_metrics_block_ru_utime:total
synapse_util_metrics_block_ru_stime_seconds | synapse_util_metrics_block_ru_stime:total
synapse_util_metrics_block_db_txn_count | synapse_util_metrics_block_db_txn_count:total
synapse_util_metrics_block_db_txn_duration_seconds | synapse_util_metrics_block_db_txn_duration:total
synapse_http_server_response_count | synapse_http_server_requests
synapse_http_server_response_count | synapse_http_server_response_time:count
synapse_http_server_response_count | synapse_http_server_response_ru_utime:count
synapse_http_server_response_count | synapse_http_server_response_ru_stime:count
synapse_http_server_response_count | synapse_http_server_response_db_txn_count:count
synapse_http_server_response_count | synapse_http_server_response_db_txn_duration:count
synapse_http_server_response_time_seconds | synapse_http_server_response_time:total
synapse_http_server_response_ru_utime_seconds | synapse_http_server_response_ru_utime:total
synapse_http_server_response_ru_stime_seconds | synapse_http_server_response_ru_stime:total
synapse_http_server_response_db_txn_count | synapse_http_server_response_db_txn_count:total
synapse_http_server_response_db_txn_duration_seconds | synapse_http_server_response_db_txn_duration:total

## Standard Metric Names

As of synapse version 0.18.2, the format of the process-wide metrics has been changed to fit prometheus standard naming conventions. Additionally the units have been changed to seconds, from miliseconds.

New name | Old name
--- | ---
process_cpu_user_seconds_total | process_resource_utime / 1000
process_cpu_system_seconds_total | process_resource_stime / 1000
process_open_fds (no 'type' label) | process_fds

The python-specific counts of garbage collector performance have been renamed.

New name | Old name
--- | ---
python_gc_time | reactor_gc_time
python_gc_unreachable_total | reactor_gc_unreachable
python_gc_counts | reactor_gc_counts

The twisted-specific reactor metrics have been renamed.

New name | Old name
--- | ---
python_twisted_reactor_pending_calls | reactor_pending_calls
python_twisted_reactor_tick_time | reactor_tick_time

# Request log format

HTTP request logs are written by synapse (see `site.py` for details).

See the following for how to decode the dense data available from the default logging configuration.

    2020-10-01 12:00:00,000 - synapse.access.http.8008 - 311 - INFO - PUT-1000- 192.168.0.1 - 8008 - {another-matrix-server.com} Processed request: 0.100sec/-0.000sec (0.000sec, 0.000sec) (0.001sec/0.090sec/3) 11B !200 "PUT /_matrix/federation/v1/send/1600000000000 HTTP/1.1" "Synapse/1.20.1" [0 dbevts]
    -AAAAAAAAAAAAAAAAAAAAA-   -BBBBBBBBBBBBBBBBBBBBBB-   -C-   -DD-   -EEEEEE-  -FFFFFFFFF-   -GG-    -HHHHHHHHHHHHHHHHHHHHHHH-                     -IIIIII- -JJJJJJJ-  -KKKKKK-, -LLLLLL-  -MMMMMMM- -NNNNNN- O  -P- -QQ-  -RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR-   -SSSSSSSSSSSS-   -TTTTTT-

Part | Explanation
--- | ---
AAAA | Timestamp request was logged (not recieved)
BBBB | Logger name (`synapse.access.(http\|https).<tag>`, where 'tag' is defined in the `listeners` config section, normally the port)
CCCC | Line number in code
DDDD | Log Level
EEEE | Request Identifier (This identifier is shared by related log lines)
FFFF | Source IP (Or X-Forwarded-For if enabled)
GGGG | Server Port
HHHH | Federated Server or Local User making request (blank if unauthenticated or not supplied)
IIII | Total Time to process the request
JJJJ | Time to send response over network once generated (this may be negative if the socket is closed before the response is generated)
KKKK | Userland CPU time
LLLL | System CPU time
MMMM | Total time waiting for a free DB connection from the pool across all parallel DB work from this request
NNNN | Total time waiting for response to DB queries across all parallel DB work from this request
OOOO | Count of DB transactions performed
PPPP | Response body size
QQQQ | Response status code (prefixed with ! if the socket was closed before the response was generated)
RRRR | Request
SSSS | User-agent
TTTT | Events fetched from DB to service this request (note that this does not include events fetched from the cache)

MMMM / NNNN can be greater than IIII if there are multiple slow database queries running in parallel.

Some actions can result in multiple identical http requests, which will return the same data, but only the first request will report time/transactions in `KKKK`/`LLLL`/`MMMM`/`NNNN`/`OOOO` - the others will be awaiting the first query to return a response and will simultaneously return with the first request, but with very small processing times.

# Contributing

This document aims to get you started with contributing to Synapse!

# 1. Who can contribute to Synapse?

Everyone is welcome to contribute code to matrix.org projects, provided that they are willing to license their contributions under the same license as the project itself. We follow a simple 'inbound=outbound' model for contributions: the act of submitting an 'inbound' contribution means that the contributor agrees to license the code under the same terms as the project's overall 'outbound' license - in our case, this is almost always Apache Software License v2 (see LICENSE).

# 2. What do I need?

The code of Synapse is written in Python 3. To do pretty much anything, you'll need a recent version of Python 3.

The source code of Synapse is hosted on GitHub. You will also need a recent version of git.

For some tests, you will need a recent version of Docker.

# 3. Get the source.

The preferred and easiest way to contribute changes is to fork the relevant project on GitHub, and then create a pull request to ask us to pull your changes into our repo.

Please base your changes on the `develop` branch.

    git clone git@github.com:YOUR_GITHUB_USER_NAME/synapse.git
    git checkout develop

If you need help getting started with git, this is beyond the scope of the document, but you can find many good git tutorials on the web.

# 4. Install the dependencies

## Under Unix (macOS, Linux, BSD, ...)

Once you have installed Python 3 and added the source, please open a terminal and setup a virtualenv, as follows:

    cd path/where/you/have/cloned/the/repository
    python3 -m venv ./env
    source ./env/bin/activate
    pip install -e ".[all,dev]"
    pip install tox

This will install the developer dependencies for the project.

## Under Windows

TBD

# 5. Get in touch.

Join our developer community on Matrix: #synapse-dev:matrix.org!

# 6. Pick an issue.

Fix your favorite problem or perhaps find a Good First Issue to work on.

# 7. Turn coffee into code and documentation!

There is a growing amount of documentation located in the `docs` directory, with a rendered version available online. This documentation is intended primarily for sysadmins running their own Synapse instance, as well as developers interacting externally with Synapse. `docs/development` exists primarily to house documentation for Synapse developers. `docs/admin_api` houses documentation regarding Synapse's Admin API, which is used mostly by sysadmins and external service developers.

Synapse's code style is documented here. Please follow it, including the conventions for the sample configuration file.

We welcome improvements and additions to our documentation itself! When writing new pages, please build `docs` to a book to check that your contributions render correctly. The docs are written in GitHub-Flavoured Markdown.

Some documentation also exists in Synapse's GitHub Wiki, although this is primarily contributed to by community authors.

# 8. Test, test, test!

While you're developing and before submitting a patch, you'll want to test your code.

## Run the linters.

The linters look at your code and do two things:

- ensure that your code follows the coding style adopted by the project;
- catch a number of errors in your code.

They're pretty fast, don't hesitate!

    source ./env/bin/activate
    ./scripts-dev/lint.sh

Note that this script will modify your files to fix styling errors. Make sure that you have saved all your files.

If you wish to restrict the linters to only the files changed since the last commit (much faster!), you can instead run:

    source ./env/bin/activate
    ./scripts-dev/lint.sh -d

Or if you know exactly which files you wish to lint, you can instead run:

    source ./env/bin/activate
    ./scripts-dev/lint.sh path/to/file1.py path/to/file2.py path/to/folder

## Run the unit tests (Twisted trial).

The unit tests run parts of Synapse, including your changes, to see if anything was broken. They are slower than the linters but will typically catch more errors.

    source ./env/bin/activate
    trial tests

If you wish to only run some unit tests, you may specify another module instead of `tests` - or a test class or a method:

    source ./env/bin/activate
    trial tests.rest.admin.test_room tests.handlers.test_admin.ExfiltrateData.test_invite

If your tests fail, you may wish to look at the logs (the default log level is `ERROR`):

    less _trial_temp/test.log

To increase the log level for the tests, set `SYNAPSE_TEST_LOG_LEVEL`:

    SYNAPSE_TEST_LOG_LEVEL=DEBUG trial tests

### Running tests under PostgreSQL

Invoking `trial` as above will use an in-memory SQLite database. This is great for quick development and testing. However, we recommend using a PostgreSQL database in production (and indeed, we have some code paths specific to each database). This means that we need to run our unit tests against PostgreSQL too. Our CI does this automatically for pull requests and release candidates, but it's sometimes useful to reproduce this locally.

To do so, configure Postgres and run `trial` with the following environment variables matching your configuration:

- `SYNAPSE_POSTGRES` to anything nonempty
- `SYNAPSE_POSTGRES_HOST`
- `SYNAPSE_POSTGRES_USER`
- `SYNAPSE_POSTGRES_PASSWORD`

For example:

    export SYNAPSE_POSTGRES=1
    export SYNAPSE_POSTGRES_HOST=localhost
    export SYNAPSE_POSTGRES_USER=postgres
    export SYNAPSE_POSTGRES_PASSWORD=mydevenvpassword
    trial

#### Prebuilt container

Since configuring PostgreSQL can be fiddly, we can make use of a pre-made Docker container to set up PostgreSQL and run our tests for us. To do so, run

    scripts-dev/test_postgresql.sh

Any extra arguments to the script will be passed to `tox` and then to `trial`, so we can run a specific test in this container with e.g.

    scripts-dev/test_postgresql.sh tests.replication.test_sharded_event_persister.EventPersisterShardTestCase

The container creates a folder in your Synapse checkout called `.tox-pg-container` and uses this as a tox environment. The output of any `trial` runs goes into `_trial_temp` in your synapse source directory — the same as running `trial` directly on your host machine.

## Run the integration tests (Sytest).

The integration tests are a more comprehensive suite of tests. They run a full version of Synapse, including your changes, to check if anything was broken. They are slower than the unit tests but will typically catch more errors.

The following command will let you run the integration test with the most common configuration:

    $ docker run --rm -it -v /path/where/you/have/cloned/the/repository\:/src:ro -v /path/to/where/you/want/logs\:/logs matrixdotorg/sytest-synapse:buster

This configuration should generally cover your needs. For more details about other configurations, see documentation in the SyTest repo.

## Run the integration tests (Complement).

Complement is a suite of black box tests that can be run on any homeserver implementation. It can also be thought of as end-to-end (e2e) tests.

It's often nice to develop on Synapse and write Complement tests at the same time. Here is how to run your local Synapse checkout against your local Complement checkout.

(checkout `complement` alongside your `synapse` checkout)

    COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh

To run a specific test file, you can pass the test name at the end of the command. The name passed comes from the naming structure in your Complement tests. If you're unsure of the name, you can do a full run and copy it from the test output:

    COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh TestBackfillingHistory

To run a specific test, you can specify the whole name structure:

    COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh TestBackfillingHistory/parallel/Backfilled_historical_events_resolve_with_proper_state_in_correct_order

### Access database for homeserver after Complement test runs.

If you're curious what the database looks like after you run some tests, here are some steps to get you going in Synapse:

1. In your Complement test comment out `defer deployment.Destroy(t)` and replace with `defer time.Sleep(2 * time.Hour)` to keep the homeserver running after the tests complete
2. Start the Complement tests
3. Find the name of the container, `docker ps -f name=complement_` (this will filter for just the Compelement related Docker containers)
4. Access the container replacing the name with what you found in the previous step: `docker exec -it complement_1_hs_with_application_service.hs1_2 /bin/bash`
5. Install sqlite (database driver), `apt-get update && apt-get install -y sqlite3`
6. Then run `sqlite3` and open the database `.open /conf/homeserver.db` (this db path comes from the Synapse homeserver.yaml)

# 9. Submit your patch.

Once you're happy with your patch, it's time to prepare a Pull Request.

To prepare a Pull Request, please:

1. verify that all the tests pass, including the coding style;
2. sign off your contribution;
3. `git push` your commit to your fork of Synapse;
4. on GitHub, create the Pull Request;
5. add a changelog entry and push it to your Pull Request;
6. for most contributors, that's all - however, if you are a member of the organization `matrix-org`, on GitHub, please request a review from `matrix.org / Synapse Core`.
7. if you need to update your PR, please avoid rebasing and just add new commits to your branch.

## Changelog

All changes, even minor ones, need a corresponding changelog / newsfragment entry. These are managed by Towncrier.

To create a changelog entry, make a new file in the `changelog.d` directory named in the format of `PRnumber.type`. The type can be one of the following:

- `feature`
- `bugfix`
- `docker` (for updates to the Docker image)
- `doc` (for updates to the documentation)
- `removal` (also used for deprecations)
- `misc` (for internal-only changes)

This file will become part of our changelog at the next release, so the content of the file should be a short description of your change in the same style as the rest of the changelog. The file can contain Markdown formatting, and should end with a full stop (.) or an exclamation mark (!) for consistency.

Adding credits to the changelog is encouraged, we value your contributions and would like to have you shouted out in the release notes!

For example, a fix in PR #1234 would have its changelog entry in `changelog.d/1234.bugfix`, and contain content like:

> The security levels of Florbs are now validated when received via the `/federation/florb` endpoint. Contributed by Jane Matrix.

If there are multiple pull requests involved in a single bugfix/feature/etc, then the content for each `changelog.d` file should be the same. Towncrier will merge the matching files together into a single changelog entry when we come to release.

### How do I know what to call the changelog file before I create the PR?

Obviously, you don't know if you should call your newsfile `1234.bugfix` or `5678.bugfix` until you create the PR, which leads to a chicken-and-egg problem.

There are two options for solving this:

1. Open the PR without a changelog file, see what number you got, and then add the changelog file to your branch (see Updating your pull request), or:

2. Look at the list of all issues/PRs, add one to the highest number you see, and quickly open the PR before somebody else claims your number.

   This script might be helpful if you find yourself doing this a lot.

Sorry, we know it's a bit fiddly, but it's really helpful for us when we come to put together a release!

### Debian changelog

Changes which affect the debian packaging files (in `debian`) are an exception to the rule that all changes require a `changelog.d` file.

In this case, you will need to add an entry to the debian changelog for the next release. For this, run the following command:

    dch

This will make up a new version number (if there isn't already an unreleased version in flight), and open an editor where you can add a new changelog entry. (Our release process will ensure that the version number and maintainer name is corrected for the release.)

If your change affects both the debian packaging and files outside the debian directory, you will need both a regular newsfragment and an entry in the debian changelog. (Though typically such changes should be submitted as two separate pull requests.)

## Sign off

In order to have a concrete record that your contribution is intentional and you agree to license it under the same terms as the project's license, we've adopted the same lightweight approach that the Linux Kernel submitting patches process, Docker, and many other projects use: the DCO (Developer Certificate of Origin: http://developercertificate.org/). This is a simple declaration that you wrote the contribution or otherwise have the right to contribute it to Matrix:

    Developer Certificate of Origin
    Version 1.1

    Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
    660 York Street, Suite 102,
    San Francisco, CA 94110 USA

    Everyone is permitted to copy and distribute verbatim copies of this
    license document, but changing it is not allowed.

    Developer's Certificate of Origin 1.1

    By making a contribution to this project, I certify that:

    (a) The contribution was created in whole or in part by me and I
        have the right to submit it under the open source license
        indicated in the file; or

    (b) The contribution is based upon previous work that, to the best
        of my knowledge, is covered under an appropriate open source
        license and I have the right under that license to submit that
        work with modifications, whether created in whole or in part
        by me, under the same open source license (unless I am
        permitted to submit under a different license), as indicated
        in the file; or

    (c) The contribution was provided directly to me by some other
        person who certified (a), (b) or (c) and I have not modified
        it.

    (d) I understand and agree that this project and the contribution
        are public and that a record of the contribution (including all
        personal information I submit with it, including my sign-off) is
        maintained indefinitely and may be redistributed consistent with
        this project or the open source license(s) involved.

If you agree to this for your contribution, then all that's needed is to include the line in your commit or pull request comment:

    Signed-off-by: Your Name <your@email.example.org>

We accept contributions under a legally identifiable name, such as your name on government documentation or common-law names (names claimed by legitimate usage or repute). Unfortunately, we cannot accept anonymous contributions at this time.

Git allows you to add this signoff automatically when using the `-s` flag to `git commit`, which uses the name and email set in your `user.name` and `user.email` git configs.

# 10. Turn feedback into better code.

Once the Pull Request is opened, you will see a few things:

1. our automated CI (Continuous Integration) pipeline will run (again) the linters, the unit tests, the integration tests and more;
2. one or more of the developers will take a look at your Pull Request and offer feedback.

From this point, you should:

1. Look at the results of the CI pipeline.
   - If there is any error, fix the error.
2. If a developer has requested changes, make these changes and let us know if it is ready for a developer to review again.
3. Create a new commit with the changes.
   - Please do NOT overwrite the history. New commits make the reviewer's life easier.
   - Push this commits to your Pull Request.
4. Back to 1.

Once both the CI and the developers are happy, the patch will be merged into Synapse and released shortly!

# 11. Find a new issue.

By now, you know the drill!

# Notes for maintainers on merging PRs etc

There are some notes for those with commit access to the project on how we manage git here.

# Conclusion

That's it! Matrix is a very open and collaborative project as you might expect given our obsession with open communication. If we're going to successfully matrix together all the fragmented communication technologies out there we are reliant on contributions and collaboration from the community to do so. So please get involved - and we hope you have as much fun hacking on Matrix as we do!

# Code Style

## Formatting tools

The Synapse codebase uses a number of code formatting tools in order to quickly and automatically check for formatting (and sometimes logical) errors in code.

The necessary tools are detailed below.

First install them with:

    pip install -e ".[lint,mypy]"

- black

  The Synapse codebase uses black as an opinionated code formatter, ensuring all comitted code is properly formatted.

  Have `black` auto-format your code (it shouldn't change any functionality) with:

      black . --exclude="\.tox|build|env"

- flake8

  `flake8` is a code checking tool. We require code to pass `flake8` before being merged into the codebase.

  Check all application and test code with:

      flake8 synapse tests

- isort

  `isort` ensures imports are nicely formatted, and can suggest and auto-fix issues such as double-importing.

  Auto-fix imports with:

      isort -rc synapse tests

  `-rc` means to recursively search the given directories.

It's worth noting that modern IDEs and text editors can run these tools automatically on save. It may be worth looking into whether this functionality is supported in your editor for a more convenient development workflow. It is not, however, recommended to run `flake8` on save as it takes a while and is very resource intensive.

## General rules

- Naming:
  - Use camel case for class and type names
  - Use underscores for functions and variables.
- Docstrings: should follow the google code style. See the examples in the sphinx documentation.
- Imports:

  - Imports should be sorted by `isort` as described above.

  - Prefer to import classes and functions rather than packages or modules.

    Example:

        from synapse.types import UserID
        ...
        user_id = UserID(local, server)

    is preferred over:

        from synapse import types
        ...
        user_id = types.UserID(local, server)

    (or any other variant).

    This goes against the advice in the Google style guide, but it means that errors in the name are caught early (at import time).

  - Avoid wildcard imports (`from synapse.types import *`) and relative imports (`from .types import UserID`).

## Configuration file format

The sample configuration file acts as a reference to Synapse's configuration options for server administrators. Remember that many readers will be unfamiliar with YAML and server administration in general, so that it is important that the file be as easy to understand as possible, which includes following a consistent format.

Some guidelines follow:

- Sections should be separated with a heading consisting of a single line prefixed and suffixed with `##`. There should be two blank lines before the section header, and one after.

- Each option should be listed in the file with the following format:

  - A comment describing the setting. Each line of this comment should be prefixed with a hash (`#`) and a space.

    The comment should describe the default behaviour (ie, what happens if the setting is omitted), as well as what the effect will be if the setting is changed.

    Often, the comment end with something like "uncomment the following to ".

  - A line consisting of only `#`.

  - A commented-out example setting, prefixed with only `#`.

    For boolean (on/off) options, convention is that this example should be the opposite to the default (so the comment will end with "Uncomment the following to enable [or disable] ." For other options, the example should give some non-default value which is likely to be useful to the reader.

- There should be a blank line between each option.

- Where several settings are grouped into a single dict, avoid the convention where the whole block is commented out, resulting in comment lines starting `# #`, as this is hard to read and confusing to edit. Instead, leave the top-level config option uncommented, and follow the conventions above for sub-options. Ensure that your code correctly handles the top-level option being set to `None` (as it will be if no sub-options are enabled).

- Lines should be wrapped at 80 characters.

- Use two-space indents.

- `true` and `false` are spelt thus (as opposed to `True`, etc.)

- Use single quotes (`'`) rather than double-quotes (`"`) or backticks (```) to refer to configuration options.

Example:

    ## Frobnication ##

    # The frobnicator will ensure that all requests are fully frobnicated.
    # To enable it, uncomment the following.
    #
    #frobnicator_enabled: true

    # By default, the frobnicator will frobnicate with the default frobber.
    # The following will make it use an alternative frobber.
    #
    #frobincator_frobber: special_frobber

    # Settings for the frobber
    #
    frobber:
      # frobbing speed. Defaults to 1.
      #
      #speed: 10

      # frobbing distance. Defaults to 1000.
      #
      #distance: 100

Note that the sample configuration is generated from the synapse code and is maintained by a script, `scripts-dev/generate_sample_config`. Making sure that the output from this script matches the desired format is left as an exercise for the reader!

# Some notes on how we use git

## On keeping the commit history clean

In an ideal world, our git commit history would be a linear progression of commits each of which contains a single change building on what came before. Here, by way of an arbitrary example, is the top of `git log --graph b2dba0607`:

Note how the commit comment explains clearly what is changing and why. Also note the absence of merge commits, as well as the absence of commits called things like (to pick a few culprits): “pep8”, “fix broken test”, “oops”, “typo”, or “Who's the president?”.

There are a number of reasons why keeping a clean commit history is a good thing:

- From time to time, after a change lands, it turns out to be necessary to revert it, or to backport it to a release branch. Those operations are much easier when the change is contained in a single commit.

- Similarly, it's much easier to answer questions like “is the fix for `/publicRooms` on the release branch?” if that change consists of a single commit.

- Likewise: “what has changed on this branch in the last week?” is much clearer without merges and “pep8” commits everywhere.

- Sometimes we need to figure out where a bug got introduced, or some behaviour changed. One way of doing that is with `git bisect`: pick an arbitrary commit between the known good point and the known bad point, and see how the code behaves. However, that strategy fails if the commit you chose is the middle of someone's epic branch in which they broke the world before putting it back together again.

One counterargument is that it is sometimes useful to see how a PR evolved as it went through review cycles. This is true, but that information is always available via the GitHub UI (or via the little-known refs/pull namespace).

Of course, in reality, things are more complicated than that. We have release branches as well as `develop` and `master`, and we deliberately merge changes between them. Bugs often slip through and have to be fixed later. That's all fine: this not a cast-iron rule which must be obeyed, but an ideal to aim towards.

## Merges, squashes, rebases: wtf?

Ok, so that's what we'd like to achieve. How do we achieve it?

The TL;DR is: when you come to merge a pull request, you probably want to “squash and merge”:

.

(This applies whether you are merging your own PR, or that of another contributor.)

“Squash and merge”1 takes all of the changes in the PR, and bundles them into a single commit. GitHub gives you the opportunity to edit the commit message before you confirm, and normally you should do so, because the default will be useless (again: `* woops typo` is not a useful thing to keep in the historical record).

The main problem with this approach comes when you have a series of pull requests which build on top of one another: as soon as you squash-merge the first PR, you'll end up with a stack of conflicts to resolve in all of the others. In general, it's best to avoid this situation in the first place by trying not to have multiple related PRs in flight at the same time. Still, sometimes that's not possible and doing a regular merge is the lesser evil.

Another occasion in which a regular merge makes more sense is a PR where you've deliberately created a series of commits each of which makes sense in its own right. For example: a PR which gradually propagates a refactoring operation through the codebase, or a PR which is the culmination of several other PRs. In this case the ability to figure out when a particular change/bug was introduced could be very useful.

Ultimately: this is not a hard-and-fast-rule. If in doubt, ask yourself “do each of the commits I am about to merge make sense in their own right”, but remember that we're just doing our best to balance “keeping the commit history clean” with other factors.

## Git branching model

A lot of words have been written in the past about git branching models (no really, a lot). I tend to think the whole thing is overblown. Fundamentally, it's not that complicated. Here's how we do it.

Let's start with a picture:

It looks complicated, but it's really not. There's one basic rule: anyone is free to merge from any more-stable branch to any less-stable branch at any time2. (The principle behind this is that if a change is good enough for the more-stable branch, then it's also good enough go put in a less-stable branch.)

Meanwhile, merging (or squashing, as per the above) from a less-stable to a more-stable branch is a deliberate action in which you want to publish a change or a set of changes to (some subset of) the world: for example, this happens when a PR is landed, or as part of our release process.

So, what counts as a more- or less-stable branch? A little reflection will show that our active branches are ordered thus, from more-stable to less-stable:

- `master` (tracks our last release).
- `release-vX.Y` (the branch where we prepare the next release)3.
- PR branches which are targeting the release.
- `develop` (our "mainline" branch containing our bleeding-edge).
- regular PR branches.

The corollary is: if you have a bugfix that needs to land in both `release-vX.Y` and `develop`, then you should base your PR on `release-vX.Y`, get it merged there, and then merge from `release-vX.Y` to `develop`. (If a fix lands in `develop` and we later need it in a release-branch, we can of course cherry-pick it, but landing it in the release branch first helps reduce the chance of annoying conflicts.)

[1]: “Squash and merge” is GitHub's term for this operation. Given that there is no merge involved, I'm not convinced it's the most intuitive name. ^

[2]: Well, anyone with commit access.^

[3]: Very, very occasionally (I think this has happened once in the history of Synapse), we've had two releases in flight at once. Obviously, `release-v1.2` is more-stable than `release-v1.3`. ^

# OpenTracing

## Background

OpenTracing is a semi-standard being adopted by a number of distributed tracing platforms. It is a common api for facilitating vendor-agnostic tracing instrumentation. That is, we can use the OpenTracing api and select one of a number of tracer implementations to do the heavy lifting in the background. Our current selected implementation is Jaeger.

OpenTracing is a tool which gives an insight into the causal relationship of work done in and between servers. The servers each track events and report them to a centralised server - in Synapse's case: Jaeger. The basic unit used to represent events is the span. The span roughly represents a single piece of work that was done and the time at which it occurred. A span can have child spans, meaning that the work of the child had to be completed for the parent span to complete, or it can have follow-on spans which represent work that is undertaken as a result of the parent but is not depended on by the parent to in order to finish.

Since this is undertaken in a distributed environment a request to another server, such as an RPC or a simple GET, can be considered a span (a unit or work) for the local server. This causal link is what OpenTracing aims to capture and visualise. In order to do this metadata about the local server's span, i.e the 'span context', needs to be included with the request to the remote.

It is up to the remote server to decide what it does with the spans it creates. This is called the sampling policy and it can be configured through Jaeger's settings.

For OpenTracing concepts see https://opentracing.io/docs/overview/what-is-tracing/.

For more information about Jaeger's implementation see https://www.jaegertracing.io/docs/

## Setting up OpenTracing

To receive OpenTracing spans, start up a Jaeger server. This can be done using docker like so:

    docker run -d --name jaeger \
      -p 6831:6831/udp \
      -p 6832:6832/udp \
      -p 5778:5778 \
      -p 16686:16686 \
      -p 14268:14268 \
      jaegertracing/all-in-one:1

Latest documentation is probably at https://www.jaegertracing.io/docs/latest/getting-started.

## Enable OpenTracing in Synapse

OpenTracing is not enabled by default. It must be enabled in the homeserver config by uncommenting the config options under `opentracing` as shown in the sample config. For example:

    opentracing:
      enabled: true
      homeserver_whitelist:
        - "mytrustedhomeserver.org"
        - "*.myotherhomeservers.com"

## Homeserver whitelisting

The homeserver whitelist is configured using regular expressions. A list of regular expressions can be given and their union will be compared when propagating any spans contexts to another homeserver.

Though it's mostly safe to send and receive span contexts to and from untrusted users since span contexts are usually opaque ids it can lead to two problems, namely:

- If the span context is marked as sampled by the sending homeserver the receiver will sample it. Therefore two homeservers with wildly different sampling policies could incur higher sampling counts than intended.
- Sending servers can attach arbitrary data to spans, known as 'baggage'. For safety this has been disabled in Synapse but that doesn't prevent another server sending you baggage which will be logged to OpenTracing's logs.

## Configuring Jaeger

Sampling strategies can be set as in this document: https://www.jaegertracing.io/docs/latest/sampling/.

# Synapse database schema files

Synapse's database schema is stored in the `synapse.storage.schema` module.

## Logical databases

Synapse supports splitting its datastore across multiple physical databases (which can be useful for large installations), and the schema files are therefore split according to the logical database they apply to.

At the time of writing, the following "logical" databases are supported:

- `state` - used to store Matrix room state (more specifically, `state_groups`, their relationships and contents).
- `main` - stores everything else.

Additionally, the `common` directory contains schema files for tables which must be present on all physical databases.

## Synapse schema versions

Synapse manages its database schema via "schema versions". These are mainly used to help avoid confusion if the Synapse codebase is rolled back after the database is updated. They work as follows:

- The Synapse codebase defines a constant `synapse.storage.schema.SCHEMA_VERSION` which represents the expectations made about the database by that version. For example, as of Synapse v1.36, this is `59`.

- The database stores a "compatibility version" in `schema_compat_version.compat_version` which defines the `SCHEMA_VERSION` of the oldest version of Synapse which will work with the database. On startup, if `compat_version` is found to be newer than `SCHEMA_VERSION`, Synapse will refuse to start.

  Synapse automatically updates this field from `synapse.storage.schema.SCHEMA_COMPAT_VERSION`.

- Whenever a backwards-incompatible change is made to the database format (normally via a `delta` file), `synapse.storage.schema.SCHEMA_COMPAT_VERSION` is also updated so that administrators can not accidentally roll back to a too-old version of Synapse.

Generally, the goal is to maintain compatibility with at least one or two previous releases of Synapse, so any substantial change tends to require multiple releases and a bit of forward-planning to get right.

As a worked example: we want to remove the `room_stats_historical` table. Here is how it might pan out.

1. Replace any code that reads from `room_stats_historical` with alternative implementations, but keep writing to it in case of rollback to an earlier version. Also, increase `synapse.storage.schema.SCHEMA_VERSION`. In this instance, there is no existing code which reads from `room_stats_historical`, so our starting point is:

   v1.36.0: `SCHEMA_VERSION=59`, `SCHEMA_COMPAT_VERSION=59`

2. Next (say in Synapse v1.37.0): remove the code that writes to `room_stats_historical`, but don’t yet remove the table in case of rollback to v1.36.0. Again, we increase `synapse.storage.schema.SCHEMA_VERSION`, but because we have not broken compatibility with v1.36, we do not yet update `SCHEMA_COMPAT_VERSION`. We now have:

   v1.37.0: `SCHEMA_VERSION=60`, `SCHEMA_COMPAT_VERSION=59`.

3. Later (say in Synapse v1.38.0): we can remove the table altogether. This will break compatibility with v1.36.0, so we must update `SCHEMA_COMPAT_VERSION` accordingly. There is no need to update `synapse.storage.schema.SCHEMA_VERSION`, since there is no change to the Synapse codebase here. So we end up with:

   v1.38.0: `SCHEMA_VERSION=60`, `SCHEMA_COMPAT_VERSION=60`.

If in doubt about whether to update `SCHEMA_VERSION` or not, it is generally best to lean towards doing so.

## Full schema dumps

In the `full_schemas` directories, only the most recently-numbered snapshot is used (`54` at the time of writing). Older snapshots (eg, `16`) are present for historical reference only.

### Building full schema dumps

If you want to recreate these schemas, they need to be made from a database that has had all background updates run.

To do so, use `scripts-dev/make_full_schema.sh`. This will produce new `full.sql.postgres` and `full.sql.sqlite` files.

Ensure postgres is installed, then run:

    ./scripts-dev/make_full_schema.sh -p postgres_username -o output_dir/

NB at the time of writing, this script predates the split into separate `state`/`main` databases so will require updates to handle that correctly.

## Boolean columns

Boolean columns require special treatment, since SQLite treats booleans the same as integers.

There are three separate aspects to this:

- Any new boolean column must be added to the `BOOLEAN_COLUMNS` list in `scripts/synapse_port_db`. This tells the port script to cast the integer value from SQLite to a boolean before writing the value to the postgres database.

- Before SQLite 3.23, `TRUE` and `FALSE` were not recognised as constants by SQLite, and the `IS [NOT] TRUE`/`IS [NOT] FALSE` operators were not supported. This makes it necessary to avoid using `TRUE` and `FALSE` constants in SQL commands.

  For example, to insert a `TRUE` value into the database, write:

      txn.execute("INSERT INTO tbl(col) VALUES (?)", (True, ))

- Default values for new boolean columns present a particular difficulty. Generally it is best to create separate schema files for Postgres and SQLite. For example:

      # in 00delta.sql.postgres:
      ALTER TABLE tbl ADD COLUMN col BOOLEAN DEFAULT FALSE;

      # in 00delta.sql.sqlite:
      ALTER TABLE tbl ADD COLUMN col BOOLEAN DEFAULT 0;

  Note that there is a particularly insidious failure mode here: the Postgres flavour will be accepted by SQLite 3.22, but will give a column whose default value is the string `"FALSE"` - which, when cast back to a boolean in Python, evaluates to `True`.

# Implementing experimental features in Synapse

It can be desirable to implement "experimental" features which are disabled by default and must be explicitly enabled via the Synapse configuration. This is applicable for features which:

- Are unstable in the Matrix spec (e.g. those defined by an MSC that has not yet been merged).
- Developers are not confident in their use by general Synapse administrators/users (e.g. a feature is incomplete, buggy, performs poorly, or needs further testing).

Note that this only really applies to features which are expected to be desirable to a broad audience. The module infrastructure should instead be investigated for non-standard features.

Guarding experimental features behind configuration flags should help with some of the following scenarios:

- Ensure that clients do not assume that unstable features exist (failing gracefully if they do not).
- Unstable features do not become de-facto standards and can be removed aggressively (since only those who have opted-in will be affected).
- Ease finding the implementation of unstable features in Synapse (for future removal or stabilization).
- Ease testing a feature (or removal of feature) due to enabling/disabling without code changes. It also becomes possible to ask for wider testing, if desired.

Experimental configuration flags should be disabled by default (requiring Synapse administrators to explicitly opt-in), although there are situations where it makes sense (from a product point-of-view) to enable features by default. This is expected and not an issue.

It is not a requirement for experimental features to be behind a configuration flag, but one should be used if unsure.

New experimental configuration flags should be added under the `experimental` configuration key (see the `synapse.config.experimental` file) and either explain (briefly) what is being enabled, or include the MSC number.

# Log Contexts

To help track the processing of individual requests, synapse uses a '`log context`' to track which request it is handling at any given moment. This is done via a thread-local variable; a `logging.Filter` is then used to fish the information back out of the thread-local variable and add it to each log record.

Logcontexts are also used for CPU and database accounting, so that we can track which requests were responsible for high CPU use or database activity.

The `synapse.logging.context` module provides facilities for managing the current log context (as well as providing the `LoggingContextFilter` class).

Asynchronous functions make the whole thing complicated, so this document describes how it all works, and how to write code which follows the rules.

In this document, "awaitable" refers to any object which can be `await`ed. In the context of Synapse, that normally means either a coroutine or a Twisted `Deferred`.

## Logcontexts without asynchronous code

In the absence of any asynchronous voodoo, things are simple enough. As with any code of this nature, the rule is that our function should leave things as it found them:

    from synapse.logging import context         # omitted from future snippets

    def handle_request(request_id):
        request_context = context.LoggingContext()

        calling_context = context.set_current_context(request_context)
        try:
            request_context.request = request_id
            do_request_handling()
            logger.debug("finished")
        finally:
            context.set_current_context(calling_context)

    def do_request_handling():
        logger.debug("phew")  # this will be logged against request_id

LoggingContext implements the context management methods, so the above can be written much more succinctly as:

    def handle_request(request_id):
        with context.LoggingContext() as request_context:
            request_context.request = request_id
            do_request_handling()
            logger.debug("finished")

    def do_request_handling():
        logger.debug("phew")

## Using logcontexts with awaitables

Awaitables break the linear flow of code so that there is no longer a single entry point where we should set the logcontext and a single exit point where we should remove it.

Consider the example above, where `do_request_handling` needs to do some blocking operation, and returns an awaitable:

    async def handle_request(request_id):
        with context.LoggingContext() as request_context:
            request_context.request = request_id
            await do_request_handling()
            logger.debug("finished")

In the above flow:

- The logcontext is set
- `do_request_handling` is called, and returns an awaitable
- `handle_request` awaits the awaitable
- Execution of `handle_request` is suspended

So we have stopped processing the request (and will probably go on to start processing the next), without clearing the logcontext.

To circumvent this problem, synapse code assumes that, wherever you have an awaitable, you will want to `await` it. To that end, whereever functions return awaitables, we adopt the following conventions:

Rules for functions returning awaitables:

> - If the awaitable is already complete, the function returns with the same logcontext it started with.
> - If the awaitable is incomplete, the function clears the logcontext before returning; when the awaitable completes, it restores the logcontext before running any callbacks.

That sounds complicated, but actually it means a lot of code (including the example above) "just works". There are two cases:

- If `do_request_handling` returns a completed awaitable, then the logcontext will still be in place. In this case, execution will continue immediately after the `await`; the "finished" line will be logged against the right context, and the `with` block restores the original context before we return to the caller.

- If the returned awaitable is incomplete, `do_request_handling` clears the logcontext before returning. The logcontext is therefore clear when `handle_request` `await`s the awaitable.

  Once `do_request_handling`'s awaitable completes, it will reinstate the logcontext, before running the second half of `handle_request`, so again the "finished" line will be logged against the right context, and the `with` block restores the original context.

As an aside, it's worth noting that `handle_request` follows our rules

- though that only matters if the caller has its own logcontext which it cares about.

The following sections describe pitfalls and helpful patterns when implementing these rules.

## Always await your awaitables

Whenever you get an awaitable back from a function, you should `await` on it as soon as possible. Do not pass go; do not do any logging; do not call any other functions.

    async def fun():
        logger.debug("starting")
        await do_some_stuff()       # just like this

        coro = more_stuff()
        result = await coro         # also fine, of course

        return result

Provided this pattern is followed all the way back up to the callchain to where the logcontext was set, this will make things work out ok: provided `do_some_stuff` and `more_stuff` follow the rules above, then so will `fun`.

It's all too easy to forget to `await`: for instance if we forgot that `do_some_stuff` returned an awaitable, we might plough on regardless. This leads to a mess; it will probably work itself out eventually, but not before a load of stuff has been logged against the wrong context. (Normally, other things will break, more obviously, if you forget to `await`, so this tends not to be a major problem in practice.)

Of course sometimes you need to do something a bit fancier with your awaitable - not all code follows the linear A-then-B-then-C pattern. Notes on implementing more complex patterns are in later sections.

## Where you create a new awaitable, make it follow the rules

Most of the time, an awaitable comes from another synapse function. Sometimes, though, we need to make up a new awaitable, or we get an awaitable back from external code. We need to make it follow our rules.

The easy way to do it is by using `context.make_deferred_yieldable`. Suppose we want to implement `sleep`, which returns a deferred which will run its callbacks after a given number of seconds. That might look like:

    # not a logcontext-rules-compliant function
    def get_sleep_deferred(seconds):
        d = defer.Deferred()
        reactor.callLater(seconds, d.callback, None)
        return d

That doesn't follow the rules, but we can fix it by calling it through `context.make_deferred_yieldable`:

    async def sleep(seconds):
        return await context.make_deferred_yieldable(get_sleep_deferred(seconds))

## Fire-and-forget

Sometimes you want to fire off a chain of execution, but not wait for its result. That might look a bit like this:

    async def do_request_handling():
        await foreground_operation()

        # *don't* do this
        background_operation()

        logger.debug("Request handling complete")

    async def background_operation():
        await first_background_step()
        logger.debug("Completed first step")
        await second_background_step()
        logger.debug("Completed second step")

The above code does a couple of steps in the background after `do_request_handling` has finished. The log lines are still logged against the `request_context` logcontext, which may or may not be desirable. There are two big problems with the above, however. The first problem is that, if `background_operation` returns an incomplete awaitable, it will expect its caller to `await` immediately, so will have cleared the logcontext. In this example, that means that 'Request handling complete' will be logged without any context.

The second problem, which is potentially even worse, is that when the awaitable returned by `background_operation` completes, it will restore the original logcontext. There is nothing waiting on that awaitable, so the logcontext will leak into the reactor and possibly get attached to some arbitrary future operation.

There are two potential solutions to this.

One option is to surround the call to `background_operation` with a `PreserveLoggingContext` call. That will reset the logcontext before starting `background_operation` (so the context restored when the deferred completes will be the empty logcontext), and will restore the current logcontext before continuing the foreground process:

    async def do_request_handling():
        await foreground_operation()

        # start background_operation off in the empty logcontext, to
        # avoid leaking the current context into the reactor.
        with PreserveLoggingContext():
            background_operation()

        # this will now be logged against the request context
        logger.debug("Request handling complete")

Obviously that option means that the operations done in `background_operation` would be not be logged against a logcontext (though that might be fixed by setting a different logcontext via a `with LoggingContext(...)` in `background_operation`).

The second option is to use `context.run_in_background`, which wraps a function so that it doesn't reset the logcontext even when it returns an incomplete awaitable, and adds a callback to the returned awaitable to reset the logcontext. In other words, it turns a function that follows the Synapse rules about logcontexts and awaitables into one which behaves more like an external function --- the opposite operation to that described in the previous section. It can be used like this:

    async def do_request_handling():
        await foreground_operation()

        context.run_in_background(background_operation)

        # this will now be logged against the request context
        logger.debug("Request handling complete")

## Passing synapse deferreds into third-party functions

A typical example of this is where we want to collect together two or more awaitables via `defer.gatherResults`:

    a1 = operation1()
    a2 = operation2()
    a3 = defer.gatherResults([a1, a2])

This is really a variation of the fire-and-forget problem above, in that we are firing off `a1` and `a2` without awaiting on them. The difference is that we now have third-party code attached to their callbacks. Anyway either technique given in the Fire-and-forget section will work.

Of course, the new awaitable returned by `gather` needs to be wrapped in order to make it follow the logcontext rules before we can yield it, as described in Where you create a new awaitable, make it follow the rules.

So, option one: reset the logcontext before starting the operations to be gathered:

    async def do_request_handling():
        with PreserveLoggingContext():
            a1 = operation1()
            a2 = operation2()
            result = await defer.gatherResults([a1, a2])

In this case particularly, though, option two, of using `context.run_in_background` almost certainly makes more sense, so that `operation1` and `operation2` are both logged against the original logcontext. This looks like:

    async def do_request_handling():
        a1 = context.run_in_background(operation1)
        a2 = context.run_in_background(operation2)

        result = await make_deferred_yieldable(defer.gatherResults([a1, a2]))

## A note on garbage-collection of awaitable chains

It turns out that our logcontext rules do not play nicely with awaitable chains which get orphaned and garbage-collected.

Imagine we have some code that looks like this:

    listener_queue = []

    def on_something_interesting():
        for d in listener_queue:
            d.callback("foo")

    async def await_something_interesting():
        new_awaitable = defer.Deferred()
        listener_queue.append(new_awaitable)

        with PreserveLoggingContext():
            await new_awaitable

Obviously, the idea here is that we have a bunch of things which are waiting for an event. (It's just an example of the problem here, but a relatively common one.)

Now let's imagine two further things happen. First of all, whatever was waiting for the interesting thing goes away. (Perhaps the request times out, or something even more interesting happens.)

Secondly, let's suppose that we decide that the interesting thing is never going to happen, and we reset the listener queue:

    def reset_listener_queue():
        listener_queue.clear()

So, both ends of the awaitable chain have now dropped their references, and the awaitable chain is now orphaned, and will be garbage-collected at some point. Note that `await_something_interesting` is a coroutine, which Python implements as a generator function. When Python garbage-collects generator functions, it gives them a chance to clean up by making the `await` (or `yield`) raise a `GeneratorExit` exception. In our case, that means that the `__exit__` handler of `PreserveLoggingContext` will carefully restore the request context, but there is now nothing waiting for its return, so the request context is never cleared.

To reiterate, this problem only arises when both ends of a awaitable chain are dropped. Dropping the the reference to an awaitable you're supposed to be awaiting is bad practice, so this doesn't actually happen too much. Unfortunately, when it does happen, it will lead to leaked logcontexts which are incredibly hard to track down.

# Replication Architecture

## Motivation

We'd like to be able to split some of the work that synapse does into multiple python processes. In theory multiple synapse processes could share a single postgresql database and we'd scale up by running more synapse processes. However much of synapse assumes that only one process is interacting with the database, both for assigning unique identifiers when inserting into tables, notifying components about new updates, and for invalidating its caches.

So running multiple copies of the current code isn't an option. One way to run multiple processes would be to have a single writer process and multiple reader processes connected to the same database. In order to do this we'd need a way for the reader process to invalidate its in-memory caches when an update happens on the writer. One way to do this is for the writer to present an append-only log of updates which the readers can consume to invalidate their caches and to push updates to listening clients or pushers.

Synapse already stores much of its data as an append-only log so that it can correctly respond to `/sync` requests so the amount of code changes needed to expose the append-only log to the readers should be fairly minimal.

## Architecture

### The Replication Protocol

See the TCP replication documentation.

### The Slaved DataStore

There are read-only version of the synapse storage layer in `synapse/replication/slave/storage` that use the response of the replication API to invalidate their caches.

# TCP Replication

## Motivation

Previously the workers used an HTTP long poll mechanism to get updates from the master, which had the problem of causing a lot of duplicate work on the server. This TCP protocol replaces those APIs with the aim of increased efficiency.

## Overview

The protocol is based on fire and forget, line based commands. An example flow would be (where '>' indicates master to worker and '<' worker to master flows):

    > SERVER example.com
    < REPLICATE
    > POSITION events master 53 53
    > RDATA events master 54 ["$foo1:bar.com", ...]
    > RDATA events master 55 ["$foo4:bar.com", ...]

The example shows the server accepting a new connection and sending its identity with the `SERVER` command, followed by the client server to respond with the position of all streams. The server then periodically sends `RDATA` commands which have the format `RDATA <stream_name> <instance_name> <token> <row>`, where the format of `<row>` is defined by the individual streams. The `<instance_name>` is the name of the Synapse process that generated the data (usually "master").

Error reporting happens by either the client or server sending an ERROR command, and usually the connection will be closed.

Since the protocol is a simple line based, its possible to manually connect to the server using a tool like netcat. A few things should be noted when manually using the protocol:

- The federation stream is only available if federation sending has been disabled on the main process.
- The server will only time connections out that have sent a `PING` command. If a ping is sent then the connection will be closed if no further commands are receieved within 15s. Both the client and server protocol implementations will send an initial PING on connection and ensure at least one command every 5s is sent (not necessarily `PING`).
- `RDATA` commands usually include a numeric token, however if the stream has multiple rows to replicate per token the server will send multiple `RDATA` commands, with all but the last having a token of `batch`. See the documentation on `commands.RdataCommand` for further details.

## Architecture

The basic structure of the protocol is line based, where the initial word of each line specifies the command. The rest of the line is parsed based on the command. For example, the RDATA command is defined as:

    RDATA <stream_name> <instance_name> <token> <row_json>

(Note that <row_json> may contains spaces, but cannot contain newlines.)

Blank lines are ignored.

### Keep alives

Both sides are expected to send at least one command every 5s or so, and should send a `PING` command if necessary. If either side do not receive a command within e.g. 15s then the connection should be closed.

Because the server may be connected to manually using e.g. netcat, the timeouts aren't enabled until an initial `PING` command is seen. Both the client and server implementations below send a `PING` command immediately on connection to ensure the timeouts are enabled.

This ensures that both sides can quickly realize if the tcp connection has gone and handle the situation appropriately.

### Start up

When a new connection is made, the server:

- Sends a `SERVER` command, which includes the identity of the server, allowing the client to detect if its connected to the expected server
- Sends a `PING` command as above, to enable the client to time out connections promptly.

The client:

- Sends a `NAME` command, allowing the server to associate a human friendly name with the connection. This is optional.
- Sends a `PING` as above
- Sends a `REPLICATE` to get the current position of all streams.
- On receipt of a `SERVER` command, checks that the server name matches the expected server name.

### Error handling

If either side detects an error it can send an `ERROR` command and close the connection.

If the client side loses the connection to the server it should reconnect, following the steps above.

### Congestion

If the server sends messages faster than the client can consume them the server will first buffer a (fairly large) number of commands and then disconnect the client. This ensures that we don't queue up an unbounded number of commands in memory and gives us a potential oppurtunity to squawk loudly. When/if the client recovers it can reconnect to the server and ask for missed messages.

### Reliability

In general the replication stream should be considered an unreliable transport since e.g. commands are not resent if the connection disappears.

The exception to that are the replication streams, i.e. RDATA commands, since these include tokens which can be used to restart the stream on connection errors.

The client should keep track of the token in the last RDATA command received for each stream so that on reconneciton it can start streaming from the correct place. Note: not all RDATA have valid tokens due to batching. See `RdataCommand` for more details.

### Example

An example iteraction is shown below. Each line is prefixed with '>' or '<' to indicate which side is sending, these are not included on the wire:

    * connection established *
    > SERVER localhost:8823
    > PING 1490197665618
    < NAME synapse.app.appservice
    < PING 1490197665618
    < REPLICATE
    > POSITION events master 1 1
    > POSITION backfill master 1 1
    > POSITION caches master 1 1
    > RDATA caches master 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513]
    > RDATA events master 14 ["$149019767112vOHxz:localhost:8823",
        "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null]
    < PING 1490197675618
    > ERROR server stopping
    * connection closed by server *

The `POSITION` command sent by the server is used to set the clients position without needing to send data with the `RDATA` command.

An example of a batched set of `RDATA` is:

    > RDATA caches master batch ["get_user_by_id",["@test:localhost:8823"],1490197670513]
    > RDATA caches master batch ["get_user_by_id",["@test2:localhost:8823"],1490197670513]
    > RDATA caches master batch ["get_user_by_id",["@test3:localhost:8823"],1490197670513]
    > RDATA caches master 54 ["get_user_by_id",["@test4:localhost:8823"],1490197670513]

In this case the client shouldn't advance their caches token until it sees the the last `RDATA`.

### List of commands

The list of valid commands, with which side can send it: server (S) or client (C):

#### SERVER (S)

Sent at the start to identify which server the client is talking to

#### RDATA (S)

A single update in a stream

#### POSITION (S)

On receipt of a POSITION command clients should check if they have missed any updates, and if so then fetch them out of band. Sent in response to a REPLICATE command (but can happen at any time).

The POSITION command includes the source of the stream. Currently all streams are written by a single process (usually "master"). If fetching missing updates via HTTP API, rather than via the DB, then processes should make the request to the appropriate process.

Two positions are included, the "new" position and the last position sent respectively. This allows servers to tell instances that the positions have advanced but no data has been written, without clients needlessly checking to see if they have missed any updates.

#### ERROR (S, C)

There was an error

#### PING (S, C)

Sent periodically to ensure the connection is still alive

#### NAME (C)

Sent at the start by client to inform the server who they are

#### REPLICATE (C)

Asks the server for the current position of all streams.

#### USER_SYNC (C)

A user has started or stopped syncing on this process.

#### CLEAR_USER_SYNC (C)

The server should clear all associated user sync data from the worker.

This is used when a worker is shutting down.

#### FEDERATION_ACK (C)

Acknowledge receipt of some federation data

### REMOTE_SERVER_UP (S, C)

Inform other processes that a remote server may have come back online.

See `synapse/replication/tcp/commands.py` for a detailed description and the format of each command.

### Cache Invalidation Stream

The cache invalidation stream is used to inform workers when they need to invalidate any of their caches in the data store. This is done by streaming all cache invalidations done on master down to the workers, assuming that any caches on the workers also exist on the master.

Each individual cache invalidation results in a row being sent down replication, which includes the cache name (the name of the function) and they key to invalidate. For example:

    > RDATA caches master 550953771 ["get_user_by_id", ["@bob:example.com"], 1550574873251]

Alternatively, an entire cache can be invalidated by sending down a `null` instead of the key. For example:

    > RDATA caches master 550953772 ["get_user_by_id", null, 1550574873252]

However, there are times when a number of caches need to be invalidated at the same time with the same key. To reduce traffic we batch those invalidations into a single poke by defining a special cache name that workers understand to mean to expand to invalidate the correct caches.

Currently the special cache names are declared in `synapse/storage/_base.py` and are:

1. `cs_cache_fake` ─ invalidates caches that depend on the current state

# Internal Documentation

This section covers implementation documentation for various parts of Synapse.

If a developer is planning to make a change to a feature of Synapse, it can be useful for general documentation of how that feature is implemented to be available. This saves the developer time in place of needing to understand how the feature works by reading the code.

Documentation that would be more useful for the perspective of a system administrator, rather than a developer who's intending to change to code, should instead be placed under the Usage section of the documentation.

# How to test SAML as a developer without a server

https://fujifish.github.io/samling/samling.html (https://github.com/fujifish/samling) is a great resource for being able to tinker with the SAML options within Synapse without needing to deploy and configure a complicated software stack.

To make Synapse (and therefore Element) use it:

1. Use the samling.html URL above or deploy your own and visit the IdP Metadata tab.
2. Copy the XML to your clipboard.
3. On your Synapse server, create a new file `samling.xml` next to your `homeserver.yaml` with the XML from step 2 as the contents.
4. Edit your `homeserver.yaml` to include:

       saml2_config:
         sp_config:
           allow_unknown_attributes: true  # Works around a bug with AVA Hashes: https://github.com/IdentityPython/pysaml2/issues/388
           metadata:
             local: ["samling.xml"]

5. Ensure that your `homeserver.yaml` has a setting for `public_baseurl`:

       public_baseurl: http://localhost:8080/

6. Run `apt-get install xmlsec1` and `pip install --upgrade --force 'pysaml2>=4.5.0'` to ensure the dependencies are installed and ready to go.
7. Restart Synapse.

Then in Element:

1. Visit the login page and point Element towards your homeserver using the `public_baseurl` above.
2. Click the Single Sign-On button.
3. On the samling page, enter a Name Identifier and add a SAML Attribute for `uid=your_localpart`. The response must also be signed.
4. Click "Next".
5. Click "Post Response" (change nothing).
6. You should be logged in.

If you try and repeat this process, you may be automatically logged in using the information you gave previously. To fix this, open your developer console (`F12` or `Ctrl+Shift+I`) while on the samling page and clear the site data. In Chrome, this will be a button on the Application tab.

# How to test CAS as a developer without a server

The django-mama-cas project is an easy to run CAS implementation built on top of Django.

## Prerequisites

1. Create a new virtualenv: `python3 -m venv <your virtualenv>`
2. Activate your virtualenv: `source /path/to/your/virtualenv/bin/activate`
3. Install Django and django-mama-cas:

       python -m pip install "django<3" "django-mama-cas==2.4.0"

4. Create a Django project in the current directory:

       django-admin startproject cas_test .

5. Follow the install directions for django-mama-cas
6. Setup the SQLite database: `python manage.py migrate`
7. Create a user:

       python manage.py createsuperuser

   1. Use whatever you want as the username and password.
   2. Leave the other fields blank.
8. Use the built-in Django test server to serve the CAS endpoints on port 8000:

       python manage.py runserver

You should now have a Django project configured to serve CAS authentication with a single user created.

## Configure Synapse (and Element) to use CAS

1. Modify your `homeserver.yaml` to enable CAS and point it to your locally running Django test server:

       cas_config:
         enabled: true
         server_url: "http://localhost:8000"
         service_url: "http://localhost:8081"
         #displayname_attribute: name
         #required_attributes:
         #    name: value

2. Restart Synapse.

Note that the above configuration assumes the homeserver is running on port 8081 and that the CAS server is on port 8000, both on localhost.

## Testing the configuration

Then in Element:

1. Visit the login page with a Element pointing at your homeserver.
2. Click the Single Sign-On button.
3. Login using the credentials created with `createsuperuser`.
4. You should be logged in.

If you want to repeat this process you'll need to manually logout first:

1. http://localhost:8000/admin/
2. Click "logout" in the top right.

# Room DAG concepts

## Edges

The word "edge" comes from graph theory lingo. An edge is just a connection between two events. In Synapse, we connect events by specifying their `prev_events`. A subsequent event points back at a previous event.

    A (oldest) <---- B <---- C (most recent)

## Depth and stream ordering

Events are normally sorted by `(topological_ordering, stream_ordering)` where `topological_ordering` is just `depth`. In other words, we first sort by `depth` and then tie-break based on `stream_ordering`. `depth` is incremented as new messages are added to the DAG. Normally, `stream_ordering` is an auto incrementing integer, but backfilled events start with `stream_ordering=-1` and decrement.

- `/sync` returns things in the order they arrive at the server (`stream_ordering`).
- `/messages` (and `/backfill` in the federation API) return them in the order determined by the event graph `(topological_ordering, stream_ordering)`.

The general idea is that, if you're following a room in real-time (i.e. `/sync`), you probably want to see the messages as they arrive at your server, rather than skipping any that arrived late; whereas if you're looking at a historical section of timeline (i.e. `/messages`), you want to see the best representation of the state of the room as others were seeing it at the time.

## Forward extremity

Most-recent-in-time events in the DAG which are not referenced by any other events' `prev_events` yet.

The forward extremities of a room are used as the `prev_events` when the next event is sent.

## Backwards extremity

The current marker of where we have backfilled up to and will generally be the oldest-in-time events we know of in the DAG.

This is an event where we haven't fetched all of the `prev_events` for.

Once we have fetched all of its `prev_events`, it's unmarked as a backwards extremity (although we may have formed new backwards extremities from the prev events during the backfilling process).

## Outliers

We mark an event as an `outlier` when we haven't figured out the state for the room at that point in the DAG yet.

We won't necessarily have the `prev_events` of an `outlier` in the database, but it's entirely possible that we might. The status of whether we have all of the `prev_events` is marked as a backwards extremity.

For example, when we fetch the event auth chain or state for a given event, we mark all of those claimed auth events as outliers because we haven't done the state calculation ourself.

## State groups

For every non-outlier event we need to know the state at that event. Instead of storing the full state for each event in the DB (i.e. a `event_id -> state` mapping), which is very space inefficient when state doesn't change, we instead assign each different set of state a "state group" and then have mappings of `event_id -> state_group` and `state_group -> state`.

### Stage group edges

TODO: `state_group_edges` is a further optimization... notes from @Azrenbeth, https://pastebin.com/seUGVGeT

# Auth Chain Difference Algorithm

The auth chain difference algorithm is used by V2 state resolution, where a naive implementation can be a significant source of CPU and DB usage.

### Definitions

A state set is a set of state events; e.g. the input of a state resolution algorithm is a collection of state sets.

The auth chain of a set of events are all the events' auth events and their auth events, recursively (i.e. the events reachable by walking the graph induced by an event's auth events links).

The auth chain difference of a collection of state sets is the union minus the intersection of the sets of auth chains corresponding to the state sets, i.e an event is in the auth chain difference if it is reachable by walking the auth event graph from at least one of the state sets but not from all of the state sets.

## Breadth First Walk Algorithm

A way of calculating the auth chain difference without calculating the full auth chains for each state set is to do a parallel breadth first walk (ordered by depth) of each state set's auth chain. By tracking which events are reachable from each state set we can finish early if every pending event is reachable from every state set.

This can work well for state sets that have a small auth chain difference, but can be very inefficient for larger differences. However, this algorithm is still used if we don't have a chain cover index for the room (e.g. because we're in the process of indexing it).

## Chain Cover Index

Synapse computes auth chain differences by pre-computing a "chain cover" index for the auth chain in a room, allowing efficient reachability queries like "is event A in the auth chain of event B". This is done by assigning every event a chain ID and sequence number (e.g. `(5,3)`), and having a map of links between chains (e.g. `(5,3) -> (2,4)`) such that A is reachable by B (i.e. `A` is in the auth chain of `B`) if and only if either:

1. A and B have the same chain ID and `A`'s sequence number is less than `B`'s sequence number; or
2. there is a link `L` between `B`'s chain ID and `A`'s chain ID such that `L.start_seq_no` <= `B.seq_no` and `A.seq_no` <= `L.end_seq_no`.

There are actually two potential implementations, one where we store links from each chain to every other reachable chain (the transitive closure of the links graph), and one where we remove redundant links (the transitive reduction of the links graph) e.g. if we have chains `C3 -> C2 -> C1` then the link `C3 -> C1` would not be stored. Synapse uses the former implementations so that it doesn't need to recurse to test reachability between chains.

### Example

An example auth graph would look like the following, where chains have been formed based on type/state_key and are denoted by colour and are labelled with `(chain ID, sequence number)`. Links are denoted by the arrows (links in grey are those that would be remove in the second implementation described above).

Note that we don't include all links between events and their auth events, as most of those links would be redundant. For example, all events point to the create event, but each chain only needs the one link from it's base to the create event.

## Using the Index

This index can be used to calculate the auth chain difference of the state sets by looking at the chain ID and sequence numbers reachable from each state set:

1. For every state set lookup the chain ID/sequence numbers of each state event
2. Use the index to find all chains and the maximum sequence number reachable from each state set.
3. The auth chain difference is then all events in each chain that have sequence numbers between the maximum sequence number reachable from any state set and the minimum reachable by all state sets (if any).

Note that steps 2 is effectively calculating the auth chain for each state set (in terms of chain IDs and sequence numbers), and step 3 is calculating the difference between the union and intersection of the auth chains.

### Worked Example

For example, given the above graph, we can calculate the difference between state sets consisting of:

1. `S1`: Alice's invite `(4,1)` and Bob's second join `(2,2)`; and
2. `S2`: Alice's second join `(4,3)` and Bob's first join `(2,1)`.

Using the index we see that the following auth chains are reachable from each state set:

1. `S1`: `(1,1)`, `(2,2)`, `(3,1)` & `(4,1)`
2. `S2`: `(1,1)`, `(2,1)`, `(3,2)` & `(4,3)`

And so, for each the ranges that are in the auth chain difference:

1. Chain 1: None, (since everything can reach the create event).
2. Chain 2: The range `(1, 2]` (i.e. just `2`), as `1` is reachable by all state sets and the maximum reachable is `2` (corresponding to Bob's second join).
3. Chain 3: Similarly the range `(1, 2]` (corresponding to the second power level).
4. Chain 4: The range `(1, 3]` (corresponding to both of Alice's joins).

So the final result is: Bob's second join `(2,2)`, the second power level `(3,2)` and both of Alice's joins `(4,2)` & `(4,3)`.

# Media Repository

Synapse implementation-specific details for the media repository

The media repository is where attachments and avatar photos are stored. It stores attachment content and thumbnails for media uploaded by local users. It caches attachment content and thumbnails for media uploaded by remote users.

## Storage

Each item of media is assigned a `media_id` when it is uploaded. The `media_id` is a randomly chosen, URL safe 24 character string.

Metadata such as the MIME type, upload time and length are stored in the sqlite3 database indexed by `media_id`.

Content is stored on the filesystem under a `"local_content"` directory.

Thumbnails are stored under a `"local_thumbnails"` directory.

The item with `media_id` `"aabbccccccccdddddddddddd"` is stored under `"local_content/aa/bb/ccccccccdddddddddddd"`. Its thumbnail with width `128` and height `96` and type `"image/jpeg"` is stored under `"local_thumbnails/aa/bb/ccccccccdddddddddddd/128-96-image-jpeg"`

Remote content is cached under `"remote_content"` directory. Each item of remote content is assigned a local `"filesystem_id"` to ensure that the directory structure `"remote_content/server_name/aa/bb/ccccccccdddddddddddd"` is appropriate. Thumbnails for remote content are stored under `"remote_thumbnail/server_name/..."`

# Room and User Statistics

Synapse maintains room and user statistics in various tables. These can be used for administrative purposes but are also used when generating the public room directory.

# Synapse Developer Documentation

## High-Level Concepts

### Definitions

- subject: Something we are tracking stats about – currently a room or user.
- current row: An entry for a subject in the appropriate current statistics table. Each subject can have only one.

### Overview

Stats correspond to the present values. Current rows contain the most up-to-date statistics for a room. Each subject can only have one entry.

# Deprecation Policy for Platform Dependencies

Synapse has a number of platform dependencies, including Python and PostgreSQL. This document outlines the policy towards which versions we support, and when we drop support for versions in the future.

## Policy

Synapse follows the upstream support life cycles for Python and PostgreSQL, i.e. when a version reaches End of Life Synapse will withdraw support for that version in future releases.

Details on the upstream support life cycles for Python and PostgreSQL are documented at https://endoflife.date/python and https://endoflife.date/postgresql.

## Context

It is important for system admins to have a clear understanding of the platform requirements of Synapse and its deprecation policies so that they can effectively plan upgrading their infrastructure ahead of time. This is especially important in contexts where upgrading the infrastructure requires auditing and approval from a security team, or where otherwise upgrading is a long process.

By following the upstream support life cycles Synapse can ensure that its dependencies continue to get security patches, while not requiring system admins to constantly update their platform dependencies to the latest versions.