Node Feature Discovery

# Developer guide

## Table of contents

## Building from source

### Download the source code

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

### Docker build

#### Build the container image

See customizing the build below for altering the container image registry, for example.

    make

#### Push the container image

Optional, this example with Docker.

    docker push <IMAGE_TAG>

### Docker multi-arch builds with buildx

The default set of architectures enabled for mulit-arch builds are `linux/amd64` and `linux/arm64`. If more architectures are needed one can override the `IMAGE_ALL_PLATFORMS` variable with a comma separated list of `OS/ARCH` tuples.

#### Build the manifest-list with a container image per arch

    make image-all

Currently `docker` does not support loading of manifest-lists meaning the images are not shown when executing `docker images`, see: buildx issue #59.

#### Push the manifest-list with container image per arch

    make push-all

The resulting container image can be used in the same way on each arch by pulling e.g. `node-feature-discovery:v0.13.4` without specifying the architecture. The manifest-list will take care of providing the right architecture image.

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

To use your published image from the step above instead of the `registry.k8s.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 below for configurability, e.g. changing the deployment namespace.

    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

    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_BUILDX_CMD | Command to build and push multi-arch images with buildx | DOCKER_CLI_EXPERIMENTAL=enabled docker buildx build –platform=${IMAGE_ALL_PLATFORMS} –progress=auto –pull
IMAGE_ALL_PLATFORMS | Comma separated list of OS/ARCH tuples for mulit-arch builds | linux/amd64,linux/arm64
IMAGE_PUSH_CMD | Command to push the image to remote registry | docker push
IMAGE_REGISTRY | Container image registry to use | registry.k8s.io/nfd
IMAGE_TAG_NAME | Container image tag name | <nfd version>
IMAGE_EXTRA_TAG_NAMES | Additional container image tag(s) to create when building image | empty
K8S_NAMESPACE | nfd-master and nfd-worker namespace | node-feature-discovery
KUBECONFIG | Kubeconfig for running e2e-tests | empty
E2E_TEST_CONFIG | Parameterization file of e2e-tests (see example) | empty
E2E_PULL_IF_NOT_PRESENT | True-ish value makes the image pull policy IfNotPresent (to be used only in e2e tests) | false
OPENSHIFT | Non-empty value enables OpenShift specific support (currently only effective in e2e tests) | empty

For example, to use a custom registry:

    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

        IMAGE_BUILD_CMD="buildah bud" make

2. by overriding the variable value

        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:

    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:

    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.

    $ export NFD_CONTAINER_IMAGE=registry.k8s.io/nfd/node-feature-discovery:v0.13.4
    $ 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

### 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:

    $ 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.

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 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:

    $ 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.

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 for up-to-date information about the required volume mounts.

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.

## Running with Tilt

Another option for building NFD locally is via Tilt tool, which can build container images, push them to a local registry and reload your Kubernetes pods automatically. When using Tilt, you don't have to build container images and re-deploy your pods manually but instead let the Tilt take care of it. Tiltfile is a configuration file for the Tilt and is located at the root directory. To develop NFD with Tilt, follow the steps below.

### Prerequisites

1. Install Docker
2. Setup Docker as a non-root user.
3. Install kubectl
4. Install kustomize
5. Install tilt
6. Create a local Kubernetes cluster

To start up your Tilt development environment, just run

    tilt up

at the root of your local NFD codebase. Tilt will start a web interface in the localhost and port 10350. From the web interface, you are able to see how NFD worker and master are progressing, watch their build and runtime logs. Once your code changes are saved locally, Tilt will notice it and re-build the container image from the current code, push the image to the registry and re-deploy NFD pods with the latest container image.

### Environment variables

To override environment variables used in the Tiltfile during image build, export them in your current terminal before starting Tilt.

    export IMAGE_TAG_NAME="v1"
    tilt up

This will override the default value(`master`) of `IMAGE_TAG_NAME` variable defined in the Tiltfile.

## Documentation

All documentation resides under the docs directory in the source tree. It is designed to be served as a html site by GitHub Pages.

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

    make site-serve

This will build the documentation in a container and serve it under 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:

    make site-build

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

Node Feature Discovery
v0.13

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This Software is under the terms of Apache License 2.0.