node-feature-discovery/docs/advanced/developer-guide.md

---
title: "Developer guide"
layout: default
sort: 1
---

# Developer guide
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## Table of contents
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1. TOC
{:toc}

---

## Building from source

### Download the source code

```bash
git clone https://github.com/kubernetes-sigs/node-feature-discovery
cd node-feature-discovery
```

### Docker build

#### Build the container image

See [customizing the build](#customizing-the-build) below for altering the
container image registry, for example.

```bash
make
```

#### Push the container image

Optional, this example with Docker.

```bash
docker push <IMAGE_TAG>
```

#### Change the job spec to use your custom image (optional)

To use your published image from the step above instead of the
`k8s.gcr.io/nfd/node-feature-discovery` image, edit `image`
attribute in the spec template(s) to the new location
(`<registry-name>/<image-name>[:<version>]`).

### Deployment

The `yamls` makefile generates a `kustomization.yaml` matching your locally
built image and using the `deploy/overlays/default` deployment. See
[build customization](#customizing-the-build) below for configurability, e.g.
changing the deployment namespace.

```bash
K8S_NAMESPACE=my-ns make yamls
kubectl apply -k .
```

You can use alternative deployment methods by modifying the auto-generated
kustomization file. For example, deploying worker and master in the same pod by
pointing to `deployment/overlays/default-combined`.

### Building locally

You can also build the binaries locally

```bash
make build
```

This will compile binaries under `bin/`

### Customizing the build

There are several Makefile variables that control the build process and the
name of the resulting container image. The following are targeted targeted for
build customization and they can be specified via environment variables or
makefile overrides.

| Variable                   | Description                                                       | Default value
| -------------------------- | ----------------------------------------------------------------- | ----------- |
| HOSTMOUNT_PREFIX           | Prefix of system directories for feature discovery (local builds) | / (*local builds*) /host- (*container builds*)
| IMAGE_BUILD_CMD            | Command to build the image                                        | docker build
| IMAGE_BUILD_EXTRA_OPTS     | Extra options to pass to build command                            | *empty*
| IMAGE_PUSH_CMD             | Command to push the image to remote registry                      | docker push
| IMAGE_REGISTRY             | Container image registry to use                                   | k8s.gcr.io/nfd
| IMAGE_TAG_NAME             | Container image tag name                                          | &lt;nfd version&gt;
| IMAGE_EXTRA_TAG_NAMES      | Additional container image tag(s) to create when building image   | *empty*
| K8S_NAMESPACE              | nfd-master and nfd-worker namespace                               | kube-system
| KUBECONFIG                 | Kubeconfig for running e2e-tests                                  | *empty*
| E2E_TEST_CONFIG            | Parameterization file of e2e-tests (see [example][e2e-config-sample]) | *empty*
| OPENSHIFT                  | Non-empty value enables OpenShift specific support (currently only effective in e2e tests) | *empty*
| BASE_IMAGE_FULL            | Container base image for target image full (--target full)        | debian:buster-slim
| BASE_IMAGE_MINIMAL         | Container base image for target image minimal (--target minimal)  | gcr.io/distroless/base

For example, to use a custom registry:

```bash
make IMAGE_REGISTRY=<my custom registry uri>
```

Or to specify a build tool different from Docker, It can be done in 2 ways:

1. via environment

    ```bash
    IMAGE_BUILD_CMD="buildah bud" make
    ```

1. by overriding the variable value

    ```bash
    make  IMAGE_BUILD_CMD="buildah bud"
    ```

### Testing

Unit tests are automatically run as part of the container image build. You can
also run them manually in the source code tree by simply running:

```bash
make test
```

End-to-end tests are built on top of the e2e test framework of Kubernetes, and,
they required a cluster to run them on. For running the tests on your test
cluster you need to specify the kubeconfig to be used:

```bash
make e2e-test KUBECONFIG=$HOME/.kube/config
```

## Running locally

You can run NFD locally, either directly on your host OS or in containers for
testing and development purposes. This may be useful e.g. for checking
features-detection.

### NFD-Master

When running as a standalone container labeling is expected to fail because
Kubernetes API is not available. Thus, it is recommended to use `-no-publish`
command line flag. E.g.

```bash
$ export NFD_CONTAINER_IMAGE={{ site.container_image }}
$ docker run --rm --name=nfd-test ${NFD_CONTAINER_IMAGE} nfd-master -no-publish
2019/02/01 14:48:21 Node Feature Discovery Master <NFD_VERSION>
2019/02/01 14:48:21 gRPC server serving on port: 8080
```

Command line flags of nfd-master:

```bash
$ docker run --rm ${NFD_CONTAINER_IMAGE} nfd-master -help
Usage of nfd-master:
  -ca-file string
        Root certificate for verifying connections
  -cert-file string
        Certificate used for authenticating connections
  -extra-label-ns value
        Comma separated list of allowed extra label namespaces
  -instance string
        Instance name. Used to separate annotation namespaces for multiple parallel deployments.
  -key-file string
        Private key matching -cert-file
  -kubeconfig string
        Kubeconfig to use
  -label-whitelist value
        Regular expression to filter label names to publish to the Kubernetes API server. NB: the label namespace is omitted i.e. the filter is only applied to the name part after '/'.
  -no-publish
        Do not publish feature labels
  -port int
        Port on which to listen for connections. (default 8080)
  -prune
        Prune all NFD related attributes from all nodes of the cluaster and exit.
  -resource-labels value
        Comma separated list of labels to be exposed as extended resources.
  -verify-node-name
        Verify worker node name against the worker's TLS certificate. Only takes effect when TLS authentication has been enabled.
  -version
        Print version and exit.
```

### NFD-Worker

In order to run nfd-worker as a "stand-alone" container against your
standalone nfd-master you need to run them in the same network namespace:

```bash
$ docker run --rm --network=container:nfd-test ${NFD_CONTAINER_IMAGE} nfd-worker
2019/02/01 14:48:56 Node Feature Discovery Worker <NFD_VERSION>
...
```

If you just want to try out feature discovery without connecting to nfd-master,
pass the `-no-publish` flag to nfd-worker.

Command line flags of nfd-worker:

```bash
$ docker run --rm ${NFD_CONTAINER_IMAGE} nfd-worker -help
Usage of nfd-worker:
  -ca-file string
        Root certificate for verifying connections
  -cert-file string
        Certificate used for authenticating connections
  -config string
        Config file to use. (default "/etc/kubernetes/node-feature-discovery/nfd-worker.conf")
  -key-file string
        Private key matching -cert-file
  -label-whitelist value
        Regular expression to filter label names to publish to the Kubernetes API server. NB: the label namespace is omitted i.e. the filter is only applied to the name part after '/'. DEPRECATED: This parameter should be set via the config file.
  -no-publish
        Do not publish discovered features, disable connection to nfd-master.
  -oneshot
        Do not publish feature labels
  -options string
        Specify config options from command line. Config options are specified in the same format as in the config file (i.e. json or yaml). These options
  -server string
        NFD server address to connecto to. (default "localhost:8080")
  -server-name-override string
        Hostname expected from server certificate, useful in testing
  -sleep-interval duration
        Time to sleep between re-labeling. Non-positive value implies no re-labeling (i.e. infinite sleep). DEPRECATED: This parameter should be set via the config file
  -sources value
        Comma separated list of feature sources. Special value 'all' enables all feature sources. DEPRECATED: This parameter should be set via the config file
  -version
        Print version and exit.
```

**NOTE** Some feature sources need certain directories and/or files from the
host mounted inside the NFD container. Thus, you need to provide Docker with the
correct `--volume` options in order for them to work correctly when run
stand-alone directly with `docker run`. See the
[default deployment](https://github.com/kubernetes-sigs/node-feature-discovery/blob/{{site.release}}/deployment/components/common/worker-mounts.yaml)
for up-to-date information about the required volume mounts.

### NFD-Topology-Updater

In order to run nfd-topology-updater as a "stand-alone" container against your
standalone nfd-master you need to run them in the same network namespace:

```bash
$ docker run --rm --network=container:nfd-test ${NFD_CONTAINER_IMAGE} nfd-topology-updater
2019/02/01 14:48:56 Node Feature Discovery Topology Updater <NFD_VERSION>
...
```

If you just want to try out feature discovery without connecting to nfd-master,
pass the `-no-publish` flag to nfd-topology-updater.

Command line flags of nfd-topology-updater:

```bash
$ docker run --rm ${NFD_CONTAINER_IMAGE} nfd-topology-updater -help
docker run --rm  quay.io/swsehgal/node-feature-discovery:v0.10.0-devel-64-g93a0a9f-dirty nfd-topology-updater -help
Usage of nfd-topology-updater:
  -add_dir_header
       If true, adds the file directory to the header of the log messages
  -alsologtostderr
       log to standard error as well as files
  -ca-file string
       Root certificate for verifying connections
  -cert-file string
       Certificate used for authenticating connections
  -key-file string
       Private key matching -cert-file
  -kubeconfig string
       Kube config file.
  -kubelet-config-file string
       Kubelet config file path. (default "/host-var/lib/kubelet/config.yaml")
  -log_backtrace_at value
       when logging hits line file:N, emit a stack trace
  -log_dir string
       If non-empty, write log files in this directory
  -log_file string
       If non-empty, use this log file
  -log_file_max_size uint
       Defines the maximum size a log file can grow to. Unit is megabytes. If the value is 0, the maximum file size is unlimited. (default 1800)
  -logtostderr
       log to standard error instead of files (default true)
  -no-publish
       Do not publish discovered features to the cluster-local Kubernetes API server.
  -one_output
       If true, only write logs to their native severity level (vs also writing to each lower severity level)
  -oneshot
       Update once and exit
  -podresources-socket string
       Pod Resource Socket path to use. (default "/host-var/lib/kubelet/pod-resources/kubelet.sock")
  -server string
       NFD server address to connecto to. (default "localhost:8080")
  -server-name-override string
       Hostname expected from server certificate, useful in testing
  -skip_headers
       If true, avoid header prefixes in the log messages
  -skip_log_headers
       If true, avoid headers when opening log files
  -sleep-interval duration
       Time to sleep between CR updates. Non-positive value implies no CR updatation (i.e. infinite sleep). [Default: 60s] (default 1m0s)
  -stderrthreshold value
       logs at or above this threshold go to stderr (default 2)
  -v value
       number for the log level verbosity
  -version
       Print version and exit.
  -vmodule value
       comma-separated list of pattern=N settings for file-filtered logging
  -watch-namespace string
       Namespace to watch pods (for testing/debugging purpose). Use * for all namespaces. (default "*")
```

NOTE:

NFD topology updater needs certain directories and/or files from the
host mounted inside the NFD container. Thus, you need to provide Docker with the
correct `--volume` options in order for them to work correctly when run
stand-alone directly with `docker run`. See the
[template spec](https://github.com/kubernetes-sigs/node-feature-discovery/blob/{{site.release}}/deployment/components/topology-updater/topologyupdater-mounts.yaml)
for up-to-date information about the required volume mounts.

[PodResource API][podresource-api] is a prerequisite for nfd-topology-updater.
Preceding Kubernetes v1.23, the `kubelet` must be started with the following flag:
`--feature-gates=KubeletPodResourcesGetAllocatable=true`.
Starting Kubernetes v1.23, the `GetAllocatableResources` is enabled by default
through `KubeletPodResourcesGetAllocatable` [feature gate][feature-gate].

## Documentation

All documentation resides under the
[docs](https://github.com/kubernetes-sigs/node-feature-discovery/tree/{{site.release}}/docs)
directory in the source tree. It is designed to be served as a html site by
[GitHub Pages](https://pages.github.com/).

Building the documentation is containerized in order to fix the build
environment. The recommended way for developing documentation is to run:

```bash
make site-serve
```

This will build the documentation in a container and serve it under
[localhost:4000/](http://localhost:4000/) making it easy to verify the results.
Any changes made to the `docs/` will automatically re-trigger a rebuild and are
reflected in the served content and can be inspected with a simple browser
refresh.

In order to just build the html documentation run:

```bash
make site-build
```

This will generate html documentation under `docs/_site/`.

<!-- Links -->
[e2e-config-sample]: https://github.com/kubernetes-sigs/node-feature-discovery/blob/{{site.release}}/test/e2e/e2e-test-config.exapmle.yaml
[podresource-api]: https://kubernetes.io/docs/concepts/extend-kubernetes/compute-storage-net/device-plugins/#monitoring-device-plugin-resources
[feature-gate]: https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates