node-feature-discovery/docs/usage/custom-resources.md

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title: "CRDs"
layout: default
sort: 7
---

# Custom Resources
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## Table of contents
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1. TOC
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---

NFD uses some Kubernetes [custom resources][custom-resources].

## NodeFeature

NodeFeature is an NFD-specific custom resource for communicating node
features and node labeling requests. The nfd-master pod watches for NodeFeature
objects, labels nodes as specified and uses the listed features as input when
evaluating [NodeFeatureRule](#nodefeaturerule)s. NodeFeature objects can be
used for implementing 3rd party extensions (see
[customization guide](customization-guide.md#nodefeature-custom-resource) for more
details).

```yaml
apiVersion: nfd.k8s-sigs.io/v1alpha1
kind: NodeFeature
metadata:
  labels:
    nfd.node.kubernetes.io/node-name: node-1
  name: node-1-vendor-features
spec:
  features:
    instances:
      vendor.device:
        elements:
        - attributes:
            model: "xpu-1"
            memory: "4000"
            type: "fast"
        - attributes:
            model: "xpu-2"
            memory: "16000"
            type: "slow"
  labels:
    vendor-xpu-present: "true"
```

## NodeFeatureGroup

NodeFeatureGroup is an NFD-specific custom resource that is designed for
grouping nodes based on their features. NFD-Master watches for NodeFeatureGroup
objects in the cluster and updates the status of the NodeFeatureGroup object
with the list of nodes that match the feature group rules. The NodeFeatureGroup
rules follow the same syntax as the NodeFeatureRule rules.

```yaml
apiVersion: nfd.k8s-sigs.io/v1alpha1
kind: NodeFeatureGroup
metadata:
  name: node-feature-group-example
spec:
  featureGroupRules:
    - name: "node has kernel version discovered"
      matchFeatures:
        - feature: kernel.version
          matchExpressions:
            major: {op: Exists}
```

## NodeFeatureRule

NodeFeatureRule is an NFD-specific custom resource that is designed for
rule-based custom labeling of nodes. NFD-Master watches for NodeFeatureRule
objects in the cluster and labels nodes according to the rules within. Some use
cases are e.g. application specific labeling in a specific environments or
being distributed by hardware vendors to create specific labels for their
devices.

```yaml
apiVersion: nfd.k8s-sigs.io/v1alpha1
kind: NodeFeatureRule
metadata:
  name: example-rule
spec:
  rules:
    - name: "example rule"
      labels:
        "example-custom-feature": "true"
      # Label is created if all of the rules below match
      matchFeatures:
        # Match if "veth" kernel module is loaded
        - feature: kernel.loadedmodule
          matchExpressions:
            veth: {op: Exists}
        # Match if any PCI device with vendor 8086 exists in the system
        - feature: pci.device
          matchExpressions:
            vendor: {op: In, value: ["8086"]}
```

See the
[Customization guide](customization-guide.md#node-feature-rule-custom-resource)
for full documentation of the NodeFeatureRule resource and its usage.

The
[`deployment/nodefeaturerule/samples/`](https://github.com/kubernetes-sigs/node-feature-discovery/tree/{{site.release}}/deployment/nodefeaturerule/samples)
directory contains sample NodeFeatureRule objects that replicate the built-in
default feature labels generated by NFD. The sample rules can be used as a base
to customize NFD feature labels. To use them in place of the the NFD built-in
labels, the corresponding feature source(s) of nfd-worker should be disabled
with the
[`core.labelSources`](../reference/worker-configuration-reference.md#corelabelsources)
configuration option.

## NodeResourceTopology

When run with NFD-Topology-Updater, NFD creates NodeResourceTopology objects
corresponding to node resource hardware topology such as:

```yaml
apiVersion: topology.node.k8s.io/v1alpha1
kind: NodeResourceTopology
metadata:
  name: node1
topologyPolicies: ["SingleNUMANodeContainerLevel"]
zones:
  - name: node-0
    type: Node
    resources:
      - name: cpu
        capacity: 20
        allocatable: 16
        available: 10
      - name: vendor/nic1
        capacity: 3
        allocatable: 3
        available: 3
  - name: node-1
    type: Node
    resources:
      - name: cpu
        capacity: 30
        allocatable: 30
        available: 15
      - name: vendor/nic2
        capacity: 6
        allocatable: 6
        available: 6
  - name: node-2
    type: Node
    resources:
      - name: cpu
        capacity: 30
        allocatable: 30
        available: 15
      - name: vendor/nic1
        capacity: 3
        allocatable: 3
        available: 3
```

The NodeResourceTopology objects created by NFD can be used to gain insight
into the allocatable resources along with the granularity of those resources at
a per-zone level (represented by node-0 and node-1 in the above example) or can
be used by an external entity (e.g. topology-aware scheduler plugin) to take an
action based on the gathered information.

<!-- Links -->
[custom-resources]: https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/