nri/plugins/device-injector

Device Injector Plugin

This sample plugin can inject Linux device nodes, CDI devices, and mounts into containers using pod annotations.

Device Annotations

Devices are annotated using the devices.noderesource.dev annotation key prefix. The key devices.noderesource.dev/container.$CONTAINER_NAME annotates devices to be injected into $CONTAINER_NAME. The keys devices.noderesource.dev and devices.noderesource.dev/pod annotate devices to be injected into containers without any other, container-specific device annotations. Only one of these latter two annotations will be ever taken into account. If both are present, devices.noderesource.dev/pod is used and devices.noderesource.dev is silently ignored, otherwise devices.noderesource.dev, in the absence of additional suffix text, is processed as shorthand for the devices.noderesource.dev/pod annotation.

For compatibility with older versions of this plugin, the prefix devices.nri.io is also supported and follows identical rules. When equivalently-specific annotations are present with both the devices.noderesource.dev prefix and the devices.nri.io prefix, the annotation with the devices.noderesource.dev prefix is used and devices.nri.io is silently ignored. In all cases, the most-specific annotation is preferred regardless of prefix.

The order of precedence is as follows:

1. devices.noderesource.dev/container.$CONTAINER_NAME
2. devices.nri.io/container.$CONTAINER_NAME
3. devices.noderesource.dev/pod
4. devices.nri.io/pod
5. devices.noderesource.dev
6. devices.nri.io

The annotation value syntax for device injection is

- path: /dev/dev0
  type: {c|b}
  major: 1
  minor: 3
  file_mode: <permission mode>
  uid: <user ID>
  gid: <group ID>
- path: /dev/dev1
  ...

file_mode, uid and gid can be omitted, the rest are mandatory.

CDI Device Annotations

CDI devices are annotated in a similar manner to devices, but using the cdi-devices.noderesource.dev annotation key prefix. As with devices, the cdi-devices.nri.io annotation key prefix is also supported.

The annotation value for CDI devices is the list of CDI device names to inject.

For instance, the following annotation

metadata:
  name: bash
  annotations:
    cdi-devices.noderesource.dev/container.c0: |
      - vendor0.com/device=null
    cdi-devices.noderesource.dev/container.c1: |
      - vendor0.com/device=zero
    cdi-devices.noderesource.dev/container.c2: |
      - vendor0.com/device=dev0
      - vendor1.com/device=dev0
      - vendor1.com/device=dev1
    cdi-devices.noderesource.dev/container.mgmt: |
      - vendor0.com/device=all

requests the injection of the CDI device vendor0.com/device=null to container c0, the injection of the CDI device vendor0.com/device=zero to container c1, the injection of the CDI devices vendor0.com/device=dev0, vendor1.com/device=dev0 and vendor1.com/device=dev1 to container c2, and the injection of the CDI device vendor0.com/device=all to container mgmt.

Mount Annotations

Mounts are annotated in a similar manner to devices, but using the mounts.noderesource.dev annotation key prefix. As with devices, the mounts.nri.io annotation key prefix is also supported.

The annotation value syntax for mount injection is

  - source: <mount source0>
    destination: <mount destination0>
    type: <mount type0>
    options:
      - option0
        option1
        ...
  - source: <mount source1>
    ...

Deployment

The NRI repository contains minimal kustomize overlays for this plugin at contrib/kustomize/device-injector.

Deploy the latest release with:

kubectl apply -k https://github.com/containerd/nri/contrib/kustomize/device-injector

Deploy a specific release with:

RELEASE_TAG=v0.10.0
kubectl apply -k "github.com/containerd/nri/contrib/kustomize/device-injector?ref=${RELEASE_TAG}"

Deploy the latest development build from tip of the main branch with:

kubectl apply -k https://github.com/containerd/nri/contrib/kustomize/device-injector/unstable

Testing

You can test this plugin using a kubernetes cluster/node with a container runtime that has NRI support enabled. Start the plugin on the target node (device-injector -idx 10), create a pod with some annotated devices or mounts, then verify that those get injected to the containers according to the annotations. See the sample pod spec for an example.