# Configuring Synapse

This is intended as a guide to the Synapse configuration. The behavior of a Synapse instance can be modified through the many configuration settings documented here — each config option is explained, including what the default is, how to change the default and what sort of behaviour the setting governs. Also included is an example configuration for each setting. If you don't want to spend a lot of time thinking about options, the config as generated sets sensible defaults for all values. Do note however that the database defaults to SQLite, which is not recommended for production usage. You can read more on this subject here.

## Config Conventions

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.

### YAML

The configuration file is a YAML file, which means that certain syntax rules apply if you want your config file to be read properly. A few helpful things to know:

- `#` before any option in the config will comment out that setting and either a default (if available) will be applied or Synapse will ignore the setting. Thus, in example #1 below, the setting will be read and applied, but in example #2 the setting will not be read and a default will be applied.

  Example #1:

      pid_file: DATADIR/homeserver.pid

  Example #2:

      #pid_file: DATADIR/homeserver.pid

- Indentation matters! The indentation before a setting will determine whether a given setting is read as part of another setting, or considered on its own. Thus, in example #1, the `enabled` setting is read as a sub-option of the `presence` setting, and will be properly applied.

  However, the lack of indentation before the `enabled` setting in example #2 means that when reading the config, Synapse will consider both `presence` and `enabled` as different settings. In this case, `presence` has no value, and thus a default applied, and `enabled` is an option that Synapse doesn't recognize and thus ignores.

  Example #1:

      presence:
        enabled: false

  Example #2:

      presence:
      enabled: false

  In this manual, all top-level settings (ones with no indentation) are identified at the beginning of their section (i.e. "Config option: `example_setting`") and the sub-options, if any, are identified and listed in the body of the section. In addition, each setting has an example of its usage, with the proper indentation shown.

## Contents

Modules

Server

Homeserver Blocking

TLS

Federation

Caching

Database

Logging

Ratelimiting

Media Store

Captcha

TURN

Registration

API Configuration

Signing Keys

Single Sign On Integration

Push

Rooms

Opentracing

Workers

Background Updates

## Modules

Server admins can expand Synapse's functionality with external modules.

See here for more documentation on how to configure or create custom modules for Synapse.

Config option: `modules`

Use the `module` sub-option to add modules under this option to extend functionality. The `module` setting then has a sub-option, `config`, which can be used to define some configuration for the `module`.

Defaults to none.

Example configuration:

    modules:
      - module: my_super_module.MySuperClass
        config:
          do_thing: true
      - module: my_other_super_module.SomeClass
        config: {}

## Server

Define your homeserver name and other base options.

Config option: `server_name`

This sets the public-facing domain of the server.

The `server_name` name will appear at the end of usernames and room addresses created on your server. For example if the `server_name` was example.com, usernames on your 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 here 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.

There is no default for this option.

Example configuration #1:

    server_name: matrix.org

Example configuration #2:

    server_name: localhost:8080

Config option: `pid_file`

When running Synapse as a daemon, the file to store the pid in. Defaults to none.

Example configuration:

    pid_file: DATADIR/homeserver.pid

Config option: `web_client_location`

The absolute URL to the web client which `/` will redirect to. Defaults to none.

Example configuration:

    web_client_location: https://riot.example.com/

Config option: `public_baseurl`

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).

Defaults to `https://<server_name>/`.

Example configuration:

    public_baseurl: https://example.com/

Config option: `serve_server_wellknown`

By default, other servers will try to reach our server on port 8448, which can be inconvenient in some environments.

Provided `https://<server_name>/` on port 443 is routed to Synapse, this option configures Synapse to serve a file at `https://<server_name>/.well-known/matrix/server`. This will tell other servers to send traffic to port 443 instead.

This option currently defaults to false.

See https://matrix-org.github.io/synapse/latest/delegate.html for more information.

Example configuration:

    serve_server_wellknown: true

Config option: `soft_file_limit`

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. Defaults to 0.

Example configuration:

    soft_file_limit: 3

Config option: `presence`

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

Example configuration:

    presence:
      enabled: false

Config option: `require_auth_for_profile_requests`

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.

Example configuration:

    require_auth_for_profile_requests: true

Config option: `limit_profile_requests_to_users_who_share_rooms`

Use this option 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.

Example configuration:

    limit_profile_requests_to_users_who_share_rooms: true

Config option: `include_profile_data_on_invite`

Use this option 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.

Example configuration:

    include_profile_data_on_invite: false

Config option: `allow_public_rooms_without_auth`

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.

Example configuration:

    allow_public_rooms_without_auth: true

Config option: `allow_public_rooms_without_auth`

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

Example configuration:

    allow_public_rooms_over_federation: true

Config option: `default_room_version`

The default room version for newly created rooms on this server.

Known room versions are listed here

For example, for room version 1, `default_room_version` should be set to "1".

Currently defaults to "9".

Example configuration:

    default_room_version: "8"

Config option: `gc_thresholds`

The garbage collection threshold parameters to pass to `gc.set_threshold`, if defined. Defaults to none.

Example configuration:

    gc_thresholds: [700, 10, 10]

Config option: `gc_min_interval`

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]`.

Example configuration:

    gc_min_interval: [0.5s, 30s, 1m]

Config option: `filter_timeline_limit`

Set the limit on the returned events in the timeline in the get and sync operations. Defaults to 100. A value of -1 means no upper limit.

Example configuration:

    filter_timeline_limit: 5000

Config option: `block_non_admin_invites`

Whether room invites to users on this server should be blocked (except those sent by local server admins). Defaults to false.

Example configuration:

    block_non_admin_invites: true

Config option: `enable_search`

If set to false, new messages will not be indexed for searching and users will receive errors when searching for messages. Defaults to true.

Example configuration:

    enable_search: false

Config option: `ip_range_blacklist`

This option prevents outgoing requests from being sent to the specified 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.

Example configuration:

    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'

Config option: `ip_range_whitelist`

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.

Example configuration:

    ip_range_whitelist:
       - '192.168.1.1'

Config option: `listeners`

List of ports that Synapse should listen on, their purpose and their configuration.

Sub-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 the docs here),

  - `metrics`: (see the docs here),

  - `replication`: (see the docs here).

- `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. Sub-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 here for more.

- `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 here.

- `openid`: OpenID authentication. See here.

- `replication`: the HTTP replication API (/_synapse/replication). See here.

- `static`: static resources under synapse/static (/_matrix/static). (Mostly useful for 'fallback authentication'.)

Example configuration #1:

    listeners:
      # TLS-enabled listener: for when matrix traffic is sent directly to synapse.
      #
      # (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]

Example configuration #2:

    listeners:
      # 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

Config option: `manhole_settings`

Connection settings for the manhole. You can find more information on the manhole here. Manhole sub-options include:

- `username` : the username for the manhole. This defaults to 'matrix'.
- `password`: The password for the manhole. This defaults to 'rabbithole'.
- `ssh_priv_key_path` and `ssh_pub_key_path`: 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.

Example configuration:

    manhole_settings:
      username: manhole
      password: mypassword
      ssh_priv_key_path: CONFDIR/id_rsa
      ssh_pub_key_path: CONFDIR/id_rsa.pub

Config option: `dummy_events_threshold`

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.

Example configuration:

    dummy_events_threshold: 5

## Homeserver blocking

Useful options for Synapse admins.

Config option: `admin_contact`

How to reach the server admin, used in `ResourceLimitError`. Defaults to none.

Example configuration:

    admin_contact: 'mailto:admin@server.com'

Config option: `hs_disabled` and `hs_disabled_message`

Blocks users from connecting to the homeserver and provides a human-readable reason why the connection was blocked. Defaults to false.

Example configuration:

    hs_disabled: true
    hs_disabled_message: 'Reason for why the HS is blocked'

Config option: `limit_usage_by_mau`

This option disables/enables monthly active user blocking. Used in cases where the admin or server owner wants to limit to the number of monthly active users. When enabled and a limit is reached the server returns a `ResourceLimitError` with error type `Codes.RESOURCE_LIMIT_EXCEEDED`. Defaults to false. If this is enabled, a value for `max_mau_value` must also be set.

Example configuration:

    limit_usage_by_mau: true

Config option: `max_mau_value`

This option sets the hard limit of monthly active users above which the server will start blocking user actions if `limit_usage_by_mau` is enabled. Defaults to 0.

Example configuration:

    max_mau_value: 50

Config option: `mau_trial_days`

The option `mau_trial_days` is a means to add a grace period for active users. It means that users must be active for the specified 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. Defaults to 0.

Example configuration:

    mau_trial_days: 5

Config option: `mau_limit_alerting`

The option `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.

Example configuration:

    mau_limit_alerting: false

Config option: `mau_stats_only`

If enabled, the metrics for the number of monthly active users will be populated, however no one will be limited based on these numbers. If `limit_usage_by_mau` is true, this is implied to be true. Defaults to false.

Example configuration:

    mau_stats_only: true

Config option: `mau_limit_reserved_threepids`

Sometimes the server admin will want to ensure certain accounts are never blocked by mau checking. These accounts are specified by this option. Defaults to none. Add accounts by specifying the `medium` and `address` of the reserved threepid (3rd party identifier).

Example configuration:

    mau_limit_reserved_threepids:
      - medium: 'email'
        address: 'reserved_user@example.com'

Config option: `server_context`

This option is used by phonehome stats to group together related servers. Defaults to none.

Example configuration:

    server_context: context

Config option: `limit_remote_rooms`

When this option 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. This is useful for homeservers that are resource-constrained. Options for this setting include:

- `enabled`: whether this check is enabled. Defaults to false.
- `complexity`: the limit above which rooms cannot be joined. The default is 1.0.
- `complexity_error`: override the error which is returned when the room is too complex with a custom message.
- `admins_can_join`: allow server admins to join complex rooms. Default is false.

Room complexity is an arbitrary measure based on factors such as the number of users in the room.

Example configuration:

    limit_remote_rooms:
      enabled: true
      complexity: 0.5
      complexity_error: "I can't let you do that, Dave."
      admins_can_join: true

Config option: `require_membership_for_aliases`

Whether to require a user to be in the room to add an alias to it. Defaults to true.

Example configuration:

    require_membership_for_aliases: false

Config option: `allow_per_room_profiles`

Whether to allow per-room membership profiles through the sending of membership events with profile information that differs from the target's global profile. Defaults to true.

Example configuration:

    allow_per_room_profiles: false

Config option: `max_avatar_size`

The largest permissible file size in bytes for a user avatar. Defaults to no restriction. Use M for MB and K for KB.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Example configuration:

    max_avatar_size: 10M

Config option: `allowed_avatar_mimetypes`

The MIME types allowed for user avatars. Defaults to no restriction.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Example configuration:

    allowed_avatar_mimetypes: ["image/png", "image/jpeg", "image/gif"]

Config option: `redaction_retention_period`

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.

Example configuration:

    redaction_retention_period: 28d

Config option: `user_ips_max_age`

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.

Example configuration:

    user_ips_max_age: 14d

Config option: `request_token_inhibit_3pid_errors`

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. Defaults to false. 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.

Example configuration:

    request_token_inhibit_3pid_errors: true

Config option: `next_link_domain_whitelist`

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.

Example configuration:

    next_link_domain_whitelist: ["matrix.org"]

Config option: `templates` and `custom_template_directory`

These options define templates to use when generating email or HTML page contents. The `custom_template_directory` determines which directory Synapse will try to find template files in 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 here for more information about using custom templates.

Example configuration:

    templates:
      custom_template_directory: /path/to/custom/templates/

Config option: `retention`

This option and the associated options determine 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.

The message retention policies feature is disabled by default.

This setting has the following sub-options:

- `default_policy`: Default retention policy. If set, Synapse will apply it to rooms that lack the 'm.room.retention' state event. This option is further specified by the `min_lifetime` and `max_lifetime` sub-options associated with it. Note that the value of `min_lifetime` doesn't matter much because Synapse doesn't take it into account yet.

- `allowed_lifetime_min` and `allowed_lifetime_max`: 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.

- `purge_jobs` and the associated `shortest_max_lifetime` and `longest_max_lifetime` sub-options: Server admins can define the settings of the background jobs purging the events whose lifetime has expired under the `purge_jobs` section.

  If no configuration is provided for this option, 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 whose `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).

Example configuration:

    retention:
      enabled: true
      default_policy:
        min_lifetime: 1d
        max_lifetime: 1y
      allowed_lifetime_min: 1d
      allowed_lifetime_max: 1y
      purge_jobs:
        - longest_max_lifetime: 3d
          interval: 12h
        - shortest_max_lifetime: 3d
          interval: 1d

## TLS

Options related to TLS.

Config option: `tls_certificate_path`

This option specifies a 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. Defaults to none.

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`).

Example configuration:

    tls_certificate_path: "CONFDIR/SERVERNAME.tls.crt"

Config option: `tls_private_key_path`

PEM-encoded private key for TLS. Defaults to none.

Example configuration:

    tls_private_key_path: "CONFDIR/SERVERNAME.tls.key"

Config option: `federation_verify_certificates` Whether to verify TLS server certificates for outbound federation requests.

Defaults to true. To disable certificate verification, set the option to false.

Example configuration:

    federation_verify_certificates: false

Config option: `federation_client_minimum_tls_version`

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.

Example configuration:

    federation_client_minimum_tls_version: 1.2

Config option: `federation_certificate_verification_whitelist`

Skip federation certificate verification on a given 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`.

Example configuration:

    federation_certificate_verification_whitelist:
      - lon.example.com
      - "*.domain.com"
      - "*.onion"

Config option: `federation_custom_ca_list`

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.

Example configuration:

    federation_custom_ca_list:
      - myCA1.pem
      - myCA2.pem
      - myCA3.pem

## Federation

Options related to federation.

Config option: `federation_domain_whitelist`

Restrict federation to the given 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.

Example configuration:

    federation_domain_whitelist:
      - lon.example.com
      - nyc.example.com
      - syd.example.com

Config option: `federation_metrics_domains`

Report prometheus metrics on the age of PDUs being sent to and received from the given 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.

Example configuration:

    federation_metrics_domains:
      - matrix.org
      - example.com

Config option: `allow_profile_lookup_over_federation`

Set to false to disable profile lookup over federation. By default, the Federation API allows other homeservers to obtain profile data of any user on this homeserver.

Example configuration:

    allow_profile_lookup_over_federation: false

Config option: `allow_device_name_lookup_over_federation`

Set this option to false 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.

Example configuration:

    allow_device_name_lookup_over_federation: false

## Caching

Options related to caching

Config option: `event_cache_size`

The number of events to cache in memory. Not affected by `caches.global_factor`. Defaults to 10K.

Example configuration:

    event_cache_size: 15K

Config option: `cache` and associated values

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.

Caching can be configured through the following sub-options:

- `global_factor`: 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 halve the size of all caches.

- `per_cache_factors`: 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`.

- `expire_caches`: Controls whether cache entries are evicted after a specified time period. Defaults to true. Set to false to disable this feature. Note that never expiring caches may result in excessive memory usage.

- `cache_entry_ttl`: If `expire_caches` is enabled, this flag controls how long an entry can be in a cache without having been accessed before being evicted. Defaults to 30m.

- `sync_response_cache_duration`: 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.

Example configuration:

    caches:
      global_factor: 1.0
      per_cache_factors:
        get_users_who_share_room_with_user: 2.0
      expire_caches: false
      sync_response_cache_duration: 2m

## Database

Config options related to database settings.

Config option: `database`

The `database` setting defines the database that synapse uses to store all of its data.

Associated sub-options:

- `name`: this option specifies the database engine to use: either `sqlite3` (for SQLite) or `psycopg2` (for PostgreSQL). If no name is specified Synapse will default to SQLite.

- `txn_limit` gives the maximum number of transactions to run per connection before reconnecting. Defaults to 0, which means no limit.

- `allow_unsafe_locale` is an option specific to Postgres. Under the default behavior, Synapse will refuse to start if the postgres db is set to a non-C locale. You can override this behavior (which is not recommended) by setting `allow_unsafe_locale` to true. Note that doing so may corrupt your database. You can find more information here and here.

- `args` gives options which are passed through to the database engine, except for options starting with `cp_`, which are used to configure the Twisted connection pool. For a reference to valid arguments, see:

  - for sqlite
  - for postgres
  - for the connection pool

For more information on using Synapse with Postgres, see here.

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

## Logging

Config options related to logging.

Config option: `log_config`

This option specifies a yaml python logging config file as described here.

Example configuration:

    log_config: "CONFDIR/SERVERNAME.log.config"

## Ratelimiting

Options related to ratelimiting in Synapse.

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.

Config option: `rc_message`

Ratelimiting settings for client messaging.

This is a ratelimiting option for messages that ratelimits sending based on the account the client is using. It defaults to: `per_second: 0.2`, `burst_count: 10`.

Example configuration:

    rc_message:
      per_second: 0.5
      burst_count: 15

Config option: `rc_registration`

This option ratelimits registration requests based on the client's IP address. It defaults to `per_second: 0.17`, `burst_count: 3`.

Example configuration:

    rc_registration:
      per_second: 0.15
      burst_count: 2

Config option: `rc_registration_token_validity`

This option checks the validity of registration tokens that ratelimits requests based on the client's IP address. Defaults to `per_second: 0.1`, `burst_count: 5`.

Example configuration:

    rc_registration_token_validity:
      per_second: 0.3
      burst_count: 6

Config option: `rc_login`

This option specifies several limits for login:

- `address` ratelimits login requests based on the client's IP address. Defaults to `per_second: 0.17`, `burst_count: 3`.

- `account` ratelimits login requests based on the account the client is attempting to log into. Defaults to `per_second: 0.17`, `burst_count: 3`.

- `failted_attempts` 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. Defaults to `per_second: 0.17`, `burst_count: 3`.

Example configuration:

    rc_login:
      address:
        per_second: 0.15
        burst_count: 5
      account:
        per_second: 0.18
        burst_count: 4
      failed_attempts:
        per_second: 0.19
        burst_count: 7

Config option: `rc_admin_redaction`

This option sets 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.

Example configuration:

    rc_admin_redaction:
      per_second: 1
      burst_count: 50

Config option: `rc_joins`

This option allows for ratelimiting number of rooms a user can join. This setting has the following sub-options:

- `local`: ratelimits when users are joining rooms the server is already in. Defaults to `per_second: 0.1`, `burst_count: 10`.

- `remote`: ratelimits when users are trying to join rooms not on the server (which can be more computationally expensive than restricting locally). Defaults to `per_second: 0.01`, `burst_count: 10`

Example configuration:

    rc_joins:
      local:
        per_second: 0.2
        burst_count: 15
      remote:
        per_second: 0.03
        burst_count: 12

Config option: `rc_3pid_validation`

This option ratelimits how often a user or IP can attempt to validate a 3PID. Defaults to `per_second: 0.003`, `burst_count: 5`.

Example configuration:

    rc_3pid_validation:
      per_second: 0.003
      burst_count: 5

Config option: `rc_invites`

This option sets ratelimiting how often invites can be sent in a room or to a specific user. `per_room` defaults to `per_second: 0.3`, `burst_count: 10` and `per_user` defaults to `per_second: 0.003`, `burst_count: 5`.

Example configuration:

    rc_invites:
      per_room:
        per_second: 0.5
        burst_count: 5
      per_user:
        per_second: 0.004
        burst_count: 3

Config option: `rc_third_party_invite`

This option ratelimits 3PID invites (i.e. invites sent to a third-party ID such as an email address or a phone number) based on the account that's sending the invite. Defaults to `per_second: 0.2`, `burst_count: 10`.

Example configuration:

    rc_third_party_invite:
      per_second: 0.2
      burst_count: 10

Config option: `rc_federation`

Defines limits on federation requests.

The `rc_federation` configuration has the following sub-options:

- `window_size`: window size in milliseconds. Defaults to 1000.
- `sleep_limit`: number of federation requests from a single server in a window before the server will delay processing the request. Defaults to 10.
- `sleep_delay`: duration in milliseconds to delay processing events from remote servers by if they go over the sleep limit. Defaults to 500.
- `reject_limit`: maximum number of concurrent federation requests allowed from a single server. Defaults to 50.
- `concurrent`: number of federation requests to concurrently process from a single server. Defaults to 3.

Example configuration:

    rc_federation:
      window_size: 750
      sleep_limit: 15
      sleep_delay: 400
      reject_limit: 40
      concurrent: 5

Config option: `federation_rr_transactions_per_room_per_second`

Sets 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. Defaults to 50.

Example configuration:

    federation_rr_transactions_per_room_per_second: 40

## Media Store

Config options relating to Synapse media store.

Config option: `enable_media_repo`

Enable the media store service in the Synapse master. Defaults to true. Set to false if you are using a separate media store worker.

Example configuration:

    enable_media_repo: false

Config option: `media_store_path`

Directory where uploaded images and attachments are stored.

Example configuration:

    media_store_path: "DATADIR/media_store"

Config option: `media_storage_providers`

Media storage providers allow media to be stored in different locations. Defaults to none. Associated sub-options are:

- `module`: type of resource, e.g. `file_system`.
- `store_local`: whether to store newly uploaded local files
- `store_remote`: whether to store newly downloaded local files
- `store_synchronous`: whether to wait for successful storage for local uploads
- `config`: sets a path to the resource through the `directory` option

Example configuration:

    media_storage_providers:
      - module: file_system
        store_local: false
        store_remote: false
        store_synchronous: false
        config:
           directory: /mnt/some/other/directory

Config option: `max_upload_size`

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. Defaults to 50M. Notably Nginx has a small max body size by default. See here for more on using a reverse proxy with Synapse.

Example configuration:

    max_upload_size: 60M

Config option: `max_image_pixels`

Maximum number of pixels that will be thumbnailed. Defaults to 32M.

Example configuration:

    max_image_pixels: 35M

Config option: `dynamic_thumbnails`

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. Defaults to false.

Example configuration:

    dynamic_thumbnails: true

Config option: `thumbnail_sizes`

List of thumbnails to precalculate when an image is uploaded. Associated sub-options are:

- `width`
- `height`
- `method`: i.e. `crop`, `scale`, etc.

Example configuration:

    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

Config option: `url_preview_enabled`

This setting determines whether the preview URL API is enabled. It is disabled by default. Set to true to enable. If enabled you must specify a `url_preview_ip_range_blacklist` blacklist.

Example configuration:

    url_preview_enabled: true

Config option: `url_preview_ip_range_blacklist`

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 use the following example list as a starting point.

Note: The value is ignored when an HTTP proxy is in use.

Example configuration:

    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'

Config option: `url_preview_ip_range_whitelist`

This option sets a 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. Defaults to none.

Example configuration:

    url_preview_ip_range_whitelist:
       - '192.168.1.1'

Config option: `url_preview_url_blacklist`

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 here for more information. Some examples are:

- `username`
- `netloc`
- `scheme`
- `path`

The values of the dictionary are treated as a 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.

Example configuration:

    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]+$'

Config option: `max_spider_size`

The largest allowed URL preview spidering size in bytes. Defaults to 10M.

Example configuration:

    max_spider_size: 8M

Config option: `url_preview_language`

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 configuration:

     url_preview_accept_language:
       - en-UK
       - en-US;q=0.9
       - fr;q=0.8
       - *;q=0.7

Config option: `oembed`

oEmbed allows for easier embedding content from a website. It can be used for generating URLs previews of services which support it. A default list of oEmbed providers is included with Synapse. Set `disable_default_providers` to true to disable using these default oEmbed URLs. Use `additional_providers` to specify additional files with oEmbed configuration (each should be in the form of providers.json). By default this list is empty.

Example configuration:

    oembed:
      disable_default_providers: true
      additional_providers:
        - oembed/my_providers.json

## Captcha

See here for full details on setting up captcha.

Config option: `recaptcha_public_key`

This homeserver's ReCAPTCHA public key. Must be specified if `enable_registration_captcha` is enabled.

Example configuration:

    recaptcha_public_key: "YOUR_PUBLIC_KEY"

Config option: `recaptcha_private_key`

This homeserver's ReCAPTCHA private key. Must be specified if `enable_registration_captcha` is enabled.

Example configuration:

    recaptcha_private_key: "YOUR_PRIVATE_KEY"

Config option: `enable_registration_captcha`

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

Example configuration:

    enable_registration_captcha: true

Config option: `recaptcha_siteverify_api`

The API endpoint to use for verifying `m.login.recaptcha` responses. Defaults to `https://www.recaptcha.net/recaptcha/api/siteverify`.

Example configuration:

    recaptcha_siteverify_api: "https://my.recaptcha.site"

## TURN

Options related to adding a TURN server to Synapse.

Config option: `turn_uris`

The public URIs of the TURN server to give to clients.

Example configuration:

    turn_uris: [turn:example.org]

Config option: `turn_shared_secret`

The shared secret used to compute passwords for the TURN server.

Example configuration:

    turn_shared_secret: "YOUR_SHARED_SECRET"

Config options: `turn_username` and `turn_password`

The Username and password if the TURN server needs them and does not use a token.

Example configuration:

    turn_username: "TURNSERVER_USERNAME"
    turn_password: "TURNSERVER_PASSWORD"

Config option: `turn_user_lifetime`

How long generated TURN credentials last. Defaults to 1h.

Example configuration:

    turn_user_lifetime: 2h

Config option: `turn_allow_guests`

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).

Example configuration:

    turn_allow_guests: false

## Registration

Registration can be rate-limited using the parameters in the Ratelimiting section of this manual.

Config option: `enable_registration`

Enable registration for new users. Defaults to false. It is highly recommended that if you enable registration, you use either captcha, email, or token-based verification to verify that new users are not bots. In order to enable registration without any verification, you must also set `enable_registration_without_verification` to true.

Example configuration:

    enable_registration: true

Config option: `enable_registration_without_verification` Enable registration without email or captcha verification. Note: this option is not recommended, as registration without verification is a known vector for spam and abuse. Defaults to false. Has no effect unless `enable_registration` is also enabled.

Example configuration:

    enable_registration_without_verification: true

Config option: `session_lifetime`

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.

Example configuration:

    session_lifetime: 24h

Config option: `refresh_access_token_lifetime`

Time that an access token remains valid for, if the session is using refresh tokens.

For more information about refresh tokens, please see the manual.

Note that this only applies to clients which advertise support for refresh tokens.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

By default, this is 5 minutes.

Example configuration:

    refreshable_access_token_lifetime: 10m

Config option: `refresh_token_lifetime: 24h`

Time that a refresh token remains valid for (provided that it is not exchanged for another one first). This option can be used to automatically log-out inactive sessions. Please see the manual for more information.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

By default, this is infinite.

Example configuration:

    refresh_token_lifetime: 24h

Config option: `nonrefreshable_access_token_lifetime`

Time that an access token remains valid for, if the session is NOT using refresh tokens.

Please note that not all clients support refresh tokens, so setting this to a short value may be inconvenient for some users who will then be logged out frequently.

Note also that this is calculated at login time: changes are not applied retrospectively to existing sessions for users that have already logged in.

By default, this is infinite.

Example configuration:

    nonrefreshable_access_token_lifetime: 24h

Config option: `registrations_require_3pid`

If this is set, the user must provide all of the specified types of 3PID when registering.

Example configuration:

    registrations_require_3pid:
      - email
      - msisdn

Config option: `disable_msisdn_registration`

Explicitly disable asking for MSISDNs from the registration flow (overrides `registrations_require_3pid` if MSISDNs are set as required).

Example configuration:

    disable_msisdn_registration: true

Config option: `allowed_local_3pids`

Mandate that users are only allowed to associate certain formats of 3PIDs with accounts on this server, as specified by the `medium` and `pattern` sub-options.

Example configuration:

    allowed_local_3pids:
      - medium: email
        pattern: '^[^@]+@matrix\.org$'
      - medium: email
        pattern: '^[^@]+@vector\.im$'
      - medium: msisdn
        pattern: '\+44'

Config option: `enable_3pid_lookup`

Enable 3PIDs lookup requests to identity servers from this server. Defaults to true.

Example configuration:

    enable_3pid_lookup: false

Config option: `registration_requires_token`

Require users to submit a token during registration. Tokens can be managed using the admin API. Note that `enable_registration` must be set to true. Disabling this option will not delete any tokens previously generated. Defaults to false. Set to true to enable.

Example configuration:

    registration_requires_token: true

Config option: `registration_shared_secret`

If set, allows registration of standard or admin accounts by anyone who has the shared secret, even if registration is otherwise disabled.

Example configuration:

    registration_shared_secret: <PRIVATE STRING>

Config option: `bcrypt_rounds`

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. Example configuration:

    bcrypt_rounds: 14

Config option: `allow_guest_access`

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. Defaults to false.

Example configuration:

    allow_guest_access: true

Config option: `default_identity_server`

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 explicitly set.)

Example configuration:

    default_identity_server: https://matrix.org

Config option: `account_threepid_delegates`

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.

Example configuration:

    account_threepid_delegates:
        email: https://example.com     # Delegate email sending to example.com
        msisdn: http://localhost:8090  # Delegate SMS sending to this local process

Config option: `enable_set_displayname`

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.

Example configuration:

    enable_set_displayname: false

Config option: `enable_set_avatar_url`

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.

Example configuration:

    enable_set_avatar_url: false

Config option: `enable_3pid_changes`

Whether users can change the third-party IDs associated with their accounts (email address and msisdn).

Defaults to true.

Example configuration:

    enable_3pid_changes: false

Config option: `auto_join_rooms`

Users who register on this homeserver will automatically be joined to the rooms listed under this option.

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. If the room already exists, make certain it is a publicly joinable room, i.e. the join rule of the room must be set to 'public'. You can find more options relating to auto-joining rooms below.

Example configuration:

    auto_join_rooms:
      - "#exampleroom:example.com"
      - "#anotherexampleroom:example.com"

Config option: `autocreate_auto_join_rooms`

Where `auto_join_rooms` are specified, setting this flag ensures that 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 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.

Example configuration:

    autocreate_auto_join_rooms: false

Config option: `autocreate_auto_join_rooms_federated`

Whether the rooms listen in `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. Set to false to prevent users from other homeservers from joining these rooms.

Example configuration:

    autocreate_auto_join_rooms_federated: false

Config option: `autocreate_auto_join_room_preset`

The room preset to use when auto-creating one of `auto_join_rooms`. Only has an effect if `autocreate_auto_join_rooms` is true.

Possible values for this option are:

- "public_chat": the room is joinable by anyone, including federated servers if `autocreate_auto_join_rooms_federated` is true (the default).
- "private_chat": an invitation is required to join these rooms.
- "trusted_private_chat": an invitation is required to join this room and the invitee is assigned a power level of 100 upon joining the room.

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".

Example configuration:

    autocreate_auto_join_room_preset: private_chat

Config option: `auto_join_mxid_localpart`

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.

Example configuration:

    auto_join_mxid_localpart: system

Config option: `auto_join_rooms_for_guests`

When `auto_join_rooms` is specified, setting this flag to false prevents guest accounts from being automatically joined to the rooms.

Defaults to true.

Example configuration:

    auto_join_rooms_for_guests: false

Config option: `inhibit_user_in_use_error`

Whether to inhibit errors raised when registering a new account if the user ID already exists. If turned on, requests to `/register/available` will always show a user ID as available, and Synapse won't raise an error when starting a registration with a user ID that already exists. However, Synapse will still raise an error if the registration completes and the username conflicts.

Defaults to false.

Example configuration:

    inhibit_user_in_use_error: true

## Metrics

Config options related to metrics.

Config option: `enable_metrics`

Set to true to enable collection and rendering of performance metrics. Defaults to false.

Example configuration:

    enable_metrics: true

Config option: `sentry`

Use this option to enable sentry integration. Provide the DSN assigned to you by sentry with the `dsn` setting.

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 disseminate sensitive information through insecure notification channels if so configured.

Example configuration:

    sentry:
        dsn: "..."

Config option: `metrics_flags`

Flags to enable Prometheus metrics which are not suitable to be enabled by default, either for performance reasons or limited use. Currently the only option is `known_servers`, which publishes `synapse_federation_known_servers`, a gauge of the number of servers this homeserver knows about, including itself. May cause performance problems on large homeservers.

Example configuration:

    metrics_flags:
        known_servers: true

Config option: `report_stats`

Whether or not to report anonymized homeserver usage statistics. This is originally set when generating the config. Set this option to true or false to change the current behavior.

Example configuration:

    report_stats: true

Config option: `report_stats_endpoint`

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

Example configuration:

    report_stats_endpoint: https://example.com/report-usage-stats/push

## API Configuration

Config settings related to the client/server API

Config option: `room_prejoin_state:`

Controls for the state that is shared with users who receive an invite to a room. 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
- m.room.topic

To change the default behavior, use the following sub-options:

- `disable_default_event_types`: set to true to disable the above defaults. If this is enabled, only the event types listed in `additional_event_types` are shared. Defaults to false.
- `additional_event_types`: 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).

Example configuration:

    room_prejoin_state:
       disable_default_event_types: true
       additional_event_types:
         - org.example.custom.event.type
         - m.room.join_rules

Config option: `track_puppeted_user_ips`

We record the IP address of clients used to access the API for various reasons, including displaying it to the user in the "Where you're signed in" dialog.

By default, when puppeting another user via the admin API, the client IP address is recorded against the user who created the access token (ie, the admin user), and not the puppeted user.

Set this option to true to also record the IP address against the puppeted user. (This also means that the puppeted user will count as an "active" user for the purpose of monthly active user tracking - see `limit_usage_by_mau` etc above.)

Example configuration:

    track_puppeted_user_ips: true

Config option: `app_service_config_files`

A list of application service config files to use.

Example configuration:

    app_service_config_files:
      - app_service_1.yaml
      - app_service_2.yaml

Config option: `track_appservice_user_ips`

Defaults to false. Set to true to enable tracking of application service IP addresses. Implicitly enables MAU tracking for application service users.

Example configuration:

    track_appservice_user_ips: true

Config option: `macaroon_secret_key`

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.

Example configuration:

    macaroon_secret_key: <PRIVATE STRING>

Config option: `form_secret`

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.

Example configuration:

    form_secret: <PRIVATE STRING>

## Signing Keys

Config options relating to signing keys

Config option: `signing_key_path`

Path to the signing key to sign messages with.

Example configuration:

    signing_key_path: "CONFDIR/SERVERNAME.signing.key"

Config option: `old_signing_keys`

The keys that the server used to sign messages with but won't use to sign new messages. 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.

Example configuration:

    old_signing_keys:
      "ed25519:id": { key: "base64string", expired_ts: 123456789123 }

Config option: `key_refresh_interval`

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. Defaults to 1d.

Example configuration:

    key_refresh_interval: 2d

Config option: `trusted_key_servers:`

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.

Example configuration #1:

    trusted_key_servers:
      - server_name: "my_trusted_server.example.com"
        verify_keys:
          "ed25519:auto": "abcdefghijklmnopqrstuvwxyzabcdefghijklmopqr"
      - server_name: "my_other_trusted_server.example.com"

Example configuration #2:

    trusted_key_servers:
      - server_name: "matrix.org"

Config option: `suppress_key_server_warning`

Set the following to true to disable the warning that is emitted when the `trusted_key_servers` include 'matrix.org'. See above.

Example configuration:

    suppress_key_server_warning: true

Config option: `key_server_signing_keys_path`

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.

Example configuration:

    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.

Config option: `saml2_config`

Enable SAML2 for registration and login. Uses pysaml2. To learn more about pysaml and to find a full list options for configuring pysaml, read the docs here.

At least one of `sp_config` or `config_path` must be set in this section to enable SAML login. You can either put your entire pysaml config inline using the `sp_config` option, or you can specify a path to a psyaml config file with the sub-option `config_path`. This setting has the following sub-options:

- `sp_config`: 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. Here are a few useful sub-options for configuring pysaml:
  - `metadata`: 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.
  - `accepted_time_diff: 3`: Allowed clock difference in seconds between the homeserver and IdP. Defaults to 0.
  - `service`: By default, the user has to go to our login page first. If you'd like to allow IdP-initiated login, set `allow_unsolicited` to true under `sp` in the `service` section.
- `config_path`: specify a separate pysaml2 configuration file thusly: `config_path: "CONFDIR/sp_conf.py"`
- `saml_session_lifetime`: 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.
- `user_mapping_provider`: Using this option, an external module can be provided as a custom solution to mapping attributes returned from a saml provider onto a matrix user. The `user_mapping_provider` has the following attributes:
  - `module`: The custom module's class.
  - `config`: Custom configuration values for the module. Use the values provided in the example if you are using the built-in user_mapping_provider, or provide your own config values for a custom class if you are using one. This section will be passed as a Python dictionary to the module's `parse_config` method. The built-in provider takes the following two options:
    - `mxid_source_attribute`: The SAML attribute (after mapping via the attribute maps) to use to derive the Matrix ID from. It is '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_mapping`: The mapping system to use for mapping the saml attribute onto a matrix ID. Options include: `hexencode` (which maps unpermitted characters to '=xx') and `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.
- `grandfathered_mxid_source_attribute`: 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'.
- `attribute_requirements`: 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 in the example. All of the listed attributes must match for the login to be permitted.
- `idp_entityid`: 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.

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`.

Example configuration:

    saml2_config:
      sp_config:
        metadata:
          local: ["saml2/idp.xml"]
          remote:
            - url: https://our_idp/metadata.xml
        accepted_time_diff: 3

        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

      saml_session_lifetime: 5m

      user_mapping_provider:
        # Below options are intended for the built-in provider, they should be
        # changed if using a custom module.
        config:
          mxid_source_attribute: displayName
          mxid_mapping: dotreplace

      grandfathered_mxid_source_attribute: upn

      attribute_requirements:
        - attribute: userGroup
          value: "staff"
        - attribute: department
          value: "sales"

      idp_entityid: 'https://our_idp/entityid'

Config option: `oidc_providers`

List of OpenID Connect (OIDC) / OAuth 2.0 identity providers, for registration and login. See here 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.)

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:///. (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, or to rely on the data returned in the id_token from the `token_endpoint`. Valid values are: `auto` or `userinfo_endpoint`. Defaults to `auto`, which uses the userinfo endpoint if `openid` is not included in `scopes`. Set to `userinfo_endpoint` to always use 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 the documentation for the `sso_auth_account_details.html` template). This template can use the `localpart_from_email` filter.

    - `confirm_localpart`: Whether to prompt the user to validate (or change) the generated localpart (see the documentation for the 'sso_auth_account_details.html' template), instead of registering the account right away.

    - `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 here:

    attribute_requirements:
         - attribute: family_name
           value: "Stephensson"
         - attribute: groups
           value: "admin"

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 above, the `family_name` claim MUST be "Stephensson", but the `groups` claim MUST contain "admin".

Example configuration:

    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"

Config option: `cas_config`

Enable Central Authentication Service (CAS) for registration and login. Has the following sub-options:

- `enabled`: Set this to true to enable authorization against a CAS server. Defaults to false.
- `server_url`: The URL of the CAS authorization endpoint.
- `displayname_attribute`: The attribute of the CAS response to use as the display name. If no name is given here, no displayname will be set.
- `required_attributes`: It is possible to configure Synapse to only allow logins if CAS attributes match particular values. All of the keys given 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.

Example configuration:

    cas_config:
      enabled: true
      server_url: "https://cas-server.com"
      displayname_attribute: name
      required_attributes:
        userGroup: "staff"
        department: None

Config option: `sso`

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 here for more information.

Options include:

- `client_whitelist`: 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/". 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 contains only the login fallback page.
- `update_profile_information`: Use this setting 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.

Example configuration:

    sso:
        client_whitelist:
          - https://riot.im/develop
          - https://my.custom.client/
        update_profile_information: true

Config option: `jwt_config`

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 here for more.

Additional sub-options for this setting include:

- `enabled`: Set to true to enable authorization using JSON web tokens. Defaults to false.
- `secret`: 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 set to true.
- `algorithm`: 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 set to true.
- `subject_claim`: Name of the claim containing a unique identifier for the user. Optional, defaults to `sub`.
- `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.
- `audiences`: 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.

Example configuration:

    jwt_config:
        enabled: true
        secret: "provided-by-your-issuer"
        algorithm: "provided-by-your-issuer"
        subject_claim: "name_of_claim"
        issuer: "provided-by-your-issuer"
        audiences:
            - "provided-by-your-issuer"

Config option: `password_config`

Use this setting to enable password-based logins.

This setting has the following sub-options:

- `enabled`: Defaults to true.
- `localdb_enabled`: Set to false 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`. Defaults to true.
- `pepper`: Set the value here to a secret random string for extra security. # Uncomment and change to a secret random string for extra security. DO NOT CHANGE THIS AFTER INITIAL SETUP!
- `policy`: Define and enforce a password policy, such as minimum lengths for passwords, etc. Each parameter is optional. This is an implementation of MSC2000. Parameters are as follows:
  - `enabled`: Defaults to false. Set to true to enable.
  - `minimum_length`: Minimum accepted length for a password. Defaults to 0.
  - `require_digit`: Whether a password must contain at least one digit. Defaults to false.
  - `require_symbol`: 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_lowercase`: Whether a password must contain at least one lowercase letter. Defaults to false.
  - `require_uppercase`: Whether a password must contain at least one uppercase letter. Defaults to false.

Example configuration:

    password_config:
       enabled: false
       localdb_enabled: false
       pepper: "EVEN_MORE_SECRET"

       policy:
          enabled: true
          minimum_length: 15
          require_digit: true
          require_symbol: true
          require_lowercase: true
          require_uppercase: true

Config option: `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).

Use the `session_timeout` sub-option here to change the time allowed for credential validation.

Example configuration:

    ui_auth:
        session_timeout: "15s"

Config option: `email`

Configuration for sending emails from Synapse.

Server admins can configure custom templates for email content. See here for more information.

This setting has the following sub-options:

- `smtp_host`: The hostname of the outgoing SMTP server to use. Defaults to 'localhost'.

- `smtp_port`: The port on the mail server for outgoing SMTP. Defaults to 25.

- `smtp_user` and `smtp_pass`: Username/password for authentication to the SMTP server. By default, no authentication is attempted.

- `require_transport_security`: Set to true 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.

- `enable_tls`: 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.

- `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 set in `app_name`, but may be overridden by the Matrix client application. Note that the placeholder must be written '%(app)s', including the trailing 's'.

- `app_name`: `app_name` defines the default value for '%(app)s' in `notif_from` and email subjects. It defaults to 'Matrix'.

- `enable_notifs`: Set to true to enable sending emails for messages that the user has missed. Disabled by default.

- `notif_for_new_users`: Set to false to disable automatic subscription to email notifications for new users. Enabled by default.

- `client_base_url`: 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.)

- `validation_token_lifetime`: Configures the time that a validation email will expire after sending. Defaults to 1h.

- `invite_client_location`: 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.

- `subjects`: Subjects to use when sending emails from Synapse. The placeholder '%(app)s' will be replaced with the value of the `app_name` setting, or by a value dictated by the Matrix client application. In addition, each subject can use the following placeholders: '%(person)s', which will be replaced by the displayname of the user(s) that sent the message(s), e.g. "Alice and Bob", and '%(room)s', which will be replaced by the name of the room the message(s) have been sent to, e.g. "My super room". In addition, emails related to account administration will can use the '%(server_name)s' placeholder, which will be replaced by the value of the `server_name` setting in your Synapse configuration.

  Here is a list of subjects for notification emails that can be set:

  - `message_from_person_in_room`: Subject to use to notify about one message from one or more user(s) in a room which has a name. Defaults to "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
  - `message_from_person`: Subject to use to notify about one message from one or more user(s) in a room which doesn't have a name. Defaults to "[%(app)s] You have a message on %(app)s from %(person)s..."
  - `messages_from_person`: Subject to use to notify about multiple messages from one or more users in a room which doesn't have a name. Defaults to "[%(app)s] You have messages on %(app)s from %(person)s..."
  - `messages_in_room`: Subject to use to notify about multiple messages in a room which has a name. Defaults to "[%(app)s] You have messages on %(app)s in the %(room)s room..."
  - `messages_in_room_and_others`: Subject to use to notify about multiple messages in multiple rooms. Defaults to "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
  - `messages_from_person_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. Defaults to "[%(app)s] You have messages on %(app)s from %(person)s and others..."
  - `invite_from_person_to_room`: Subject to use to notify about an invite to a room which has a name. Defaults to "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
  - `invite_from_person`: Subject to use to notify about an invite to a room which doesn't have a name. Defaults to "[%(app)s] %(person)s has invited you to chat on %(app)s..."
  - `password_reset`: Subject to use when sending a password reset email. Defaults to "[%(server_name)s] Password reset"
  - `email_validation`: Subject to use when sending a verification email to assert an address's ownership. Defaults to "[%(server_name)s] Validate your email"

Example configuration:

    email:
      smtp_host: mail.server
      smtp_port: 587
      smtp_user: "exampleusername"
      smtp_pass: "examplepassword"
      require_transport_security: true
      enable_tls: false
      notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
      app_name: my_branded_matrix_server
      enable_notifs: true
      notif_for_new_users: false
      client_base_url: "http://localhost/riot"
      validation_token_lifetime: 15m
      invite_client_location: https://app.element.io

      subjects:
        message_from_person_in_room: "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
        message_from_person: "[%(app)s] You have a message on %(app)s from %(person)s..."
        messages_from_person: "[%(app)s] You have messages on %(app)s from %(person)s..."
        messages_in_room: "[%(app)s] You have messages on %(app)s in the %(room)s room..."
        messages_in_room_and_others: "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
        messages_from_person_and_others: "[%(app)s] You have messages on %(app)s from %(person)s and others..."
        invite_from_person_to_room: "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
        invite_from_person: "[%(app)s] %(person)s has invited you to chat on %(app)s..."
        password_reset: "[%(server_name)s] Password reset"
        email_validation: "[%(server_name)s] Validate your email"

## Push

Configuration settings related to push notifications

Config option: `push`

This setting defines options for push notifications.

This option has a number of sub-options. They are as follows:

- `include_content`: 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 to have the body sent, this option controls whether the notification request includes the content of the event (other details like the sender are still included). If `event_id_only` is enabled, 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. Defaults to true. Set to false to only include the event ID and room ID in push notification payloads.
- `group_unread_count_by_room: 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. Defaults to true, meaning push clients will see the number of rooms with unread messages in them. Set to false to instead send the number of unread messages.

Example configuration:

    push:
      include_content: false
      group_unread_count_by_room: false

## Rooms

Config options relating to rooms.

Config option: `encryption_enabled_by_default`

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.

Example configuration:

    encryption_enabled_by_default_for_room_type: invite

Config option: `enable_group_creation`

Set to true to allow non-server-admin users to create groups on this server

Example configuration:

    enable_group_creation: true

Config option: `group_creation_prefix`

If enabled/present, non-server admins can only create groups with local parts starting with this prefix.

Example configuration:

    group_creation_prefix: "unofficial_"

Config option: `user_directory`

This setting defines options related to the user directory.

This option has the following sub-options:

- `enabled`: Defines whether users can search the user directory. If false then empty responses are returned to all queries. Defaults to true.
- `search_all_users`: 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 via API following the instructions at https://matrix-org.github.io/synapse/latest/usage/administration/admin_api/background_updates.html#run Set to true to return search results containing all known users, even if that user does not share a room with the requester.
- `prefer_local_users`: Defines whether to prefer local users in search query results. If set to true, local users are more likely to appear above remote users when searching the user directory. Defaults to false.

Example configuration:

    user_directory:
        enabled: false
        search_all_users: true
        prefer_local_users: true

Config option: `user_consent`

For detailed instructions on user consent configuration, see here.

Parts of this section are required if enabling the `consent` resource under `listeners`, in particular `template_dir` and `version`. # TODO: link `listeners`

- `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 .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 ##TODO: link 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".

Example configuration:

    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

Config option: `stats`

Settings for local room and user statistics collection. See here for more.

- `enabled`: Set to false to disable room and user statistics. Note that doing so may cause certain features (such as the room directory) not to work correctly. Defaults to true.

Example configuration:

    stats:
      enabled: false

Config option: `server_notices`

Use this setting to enable a room which can be used to send notices from the server to users. It is a special room which users cannot leave; notices in the room come from a special "notices" user id.

If you use this setting, you must define the `system_mxid_localpart` sub-setting, which defines the id of the user which will be used to send the notices.

Sub-options for this setting include:

- `system_mxid_display_name`: set the display name of the "notices" user
- `system_mxid_avatar_url`: set the avatar for the "notices" user
- `room_name`: set the room name of the server notices room

Example configuration:

    server_notices:
      system_mxid_localpart: notices
      system_mxid_display_name: "Server Notices"
      system_mxid_avatar_url: "mxc://server.com/oumMVlgDnLYFaPVkExemNVVZ"
      room_name: "Server Notices"

Config option: `enable_room_list_search`

Set to false 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. Defaults to true.

Example configuration:

    enable_room_list_search: false

Config option: `alias_creation`

The `alias_creation` option controls who is 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. Defaults to "*".
- `alias`: Matches against the alias being created. Defaults to "*".
- `room_id`: Matches against the room ID the alias is being pointed at. Defaults to "*"
- `action`: Whether to "allow" or "deny" the request if the rule matches. Defaults to allow.

Example configuration:

    alias_creation_rules:
      - user_id: "bad_user"
        alias: "spammy_alias"
        room_id: "*"
        action: deny

Config options: `room_list_publication_rules`

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. Defaults to "*".
- `alias`: Matches against any current local or canonical aliases associated with the room. Defaults to "*".
- `room_id`: Matches against the room ID being published. Defaults to "*".
- `action`: Whether to "allow" or "deny" the request if the rule matches. Defaults to allow.

Example configuration:

    room_list_publication_rules:
      - user_id: "*"
        alias: "*"
        room_id: "*"
        action: allow

## Opentracing

Configuration options related to Opentracing support.

Config option: `opentracing`

These settings enable and configure 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 services which support opentracing (specifically those implemented with Jaeger).

Sub-options include:

- `enabled`: whether tracing is enabled. Set to true to enable. Disabled by default.
- `homeserver_whitelist`: The list of homeservers we wish to send and receive span contexts and span baggage. See here for more. 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.
- `force_tracing_for_users`: # 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.
- `jaeger_config`: 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.

Example configuration:

    opentracing:
        enabled: true
        homeserver_whitelist:
          - ".*"
        force_tracing_for_users:
          - "@user1:server_name"
          - "@user2:server_name"

        jaeger_config:
          sampler:
            type: const
            param: 1
          logging:
            false

## Workers

Configuration options related to workers.

Config option: `send_federation`

Controls sending of outbound federation transactions on the main process. Set to false if using a federation sender worker. Defaults to true.

Example configuration:

    send_federation: false

Config option: `federation_sender_instances`

It is possible to run multiple federation sender workers, in which case the work is balanced across them. Use this setting to list the senders.

This configuration setting 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).

Example configuration:

    federation_sender_instances:
      - federation_sender1

Config option: `instance_map`

When using workers this should be a map from worker name to the HTTP replication listener of the worker, if configured.

Example configuration:

    instance_map:
      worker1:
        host: localhost
        port: 8034

Config option: `stream_writers`

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`.

Example configuration:

    stream_writers:
      events: worker1
      typing: worker1

Config option: `run_background_task_on`

The worker that is used to run background tasks (e.g. cleaning up expired data). If not provided this defaults to the main process.

Example configuration:

    run_background_tasks_on: worker1

Config option: `worker_replication_secret`

A shared secret used by the replication APIs to authenticate HTTP requests from workers.

By default this is unused and traffic is not authenticated.

Example configuration:

    worker_replication_secret: "secret_secret"

Config option: `redis`

Configuration for Redis when using workers. This must be enabled when using workers (unless using old style direct TCP configuration). This setting has the following sub-options:

- `enabled`: whether to use Redis support. Defaults to false.
- `host` and `port`: Optional host and port to use to connect to redis. Defaults to localhost and 6379
- `password`: Optional password if configured on the Redis instance.

Example configuration:

    redis:
      enabled: true
      host: localhost
      port: 6379
      password: <secret_password>

## Background Updates

Configuration settings related to background updates.

Config option: `background_updates`

Background updates are database updates that are run in the background in batches. The duration, minimum batch size, default batch size, whether to sleep between batches and if so, how long to sleep can all be configured. This is helpful to speed up or slow down the updates. This setting has the following sub-options:

- `background_update_duration_ms`: How long in milliseconds to run a batch of background updates for. Defaults to 100. Set a different time to change the default.
- `sleep_enabled`: Whether to sleep between updates. Defaults to true. Set to false to change the default.
- `sleep_duration_ms`: If sleeping between updates, how long in milliseconds to sleep for. Defaults to 1000. Set a duration to change the default.
- `min_batch_size`: Minimum size a batch of background updates can be. Must be greater than 0. Defaults to 1. Set a size to change the default.
- `default_batch_size`: The batch size to use for the first iteration of a new background update. The default is 100. Set a size to change the default.

Example configuration:

    background_updates:
        background_update_duration_ms: 500
        sleep_enabled: false
        sleep_duration_ms: 300
        min_batch_size: 10
        default_batch_size: 50