Introduction

Table of contents

1. NFD-Master
2. NFD-Worker
3. NFD-Topology-Updater
4. Feature Discovery
5. Node annotations
6. NodeResourceTopology CR

This software enables node feature discovery for Kubernetes. It detects hardware features available on each node in a Kubernetes cluster, and advertises those features using node labels.

NFD consists of three software components:

1. nfd-master
2. nfd-worker
3. nfd-topology-updater

NFD-Master

NFD-Master is the daemon responsible for communication towards the Kubernetes API. That is, it receives labeling requests from the worker and modifies node objects accordingly.

NFD-Worker

NFD-Worker is a daemon responsible for feature detection. It then communicates the information to nfd-master which does the actual node labeling. One instance of nfd-worker is supposed to be running on each node of the cluster,

NFD-Topology-Updater

NFD-Topology-Updater is a daemon responsible for examining allocated resources on a worker node to account for resources available to be allocated to new pod on a per-zone basis (where a zone can be a NUMA node). It then communicates the information to nfd-master which does the NodeResourceTopology CR creation corresponding to all the nodes in the cluster. One instance of nfd-topology-updater is supposed to be running on each node of the cluster.

Feature Discovery

Feature discovery is divided into domain-specific feature sources:

• CPU
• Kernel
• Memory
• Network
• PCI
• Storage
• System
• USB
• Custom (rule-based custom features)
• Local (hooks for user-specific features)
• IOMMU (deprecated)

Each feature source is responsible for detecting a set of features which. in turn, are turned into node feature labels. Feature labels are prefixed with feature.node.kubernetes.io/ and also contain the name of the feature source. Non-standard user-specific feature labels can be created with the local and custom feature sources.

An overview of the default feature labels:

{
  "feature.node.kubernetes.io/cpu-<feature-name>": "true",
  "feature.node.kubernetes.io/custom-<feature-name>": "true",
  "feature.node.kubernetes.io/kernel-<feature name>": "<feature value>",
  "feature.node.kubernetes.io/memory-<feature-name>": "true",
  "feature.node.kubernetes.io/network-<feature-name>": "true",
  "feature.node.kubernetes.io/pci-<device label>.present": "true",
  "feature.node.kubernetes.io/storage-<feature-name>": "true",
  "feature.node.kubernetes.io/system-<feature name>": "<feature value>",
  "feature.node.kubernetes.io/usb-<device label>.present": "<feature value>",
  "feature.node.kubernetes.io/<file name>-<feature name>": "<feature value>"
}

Node annotations

NFD also annotates nodes it is running on:

NOTE: the -instance command line flag affects the annotation names

Unapplicable annotations are not created, i.e. for example master.version is only created on nodes running nfd-master.

NodeResourceTopology CR

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

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