mirror of
https://github.com/kubernetes-sigs/node-feature-discovery.git
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6171c745a4
Introduce two main sections "Deployment" and "Usage" and move "Developer guide" to the top level, too. In particular, split the huge deployment-and-usage file into multiple parts under the new main sections. Move customization guide from "Advanced" to "Usage". This patch also renames "Advanced" to "Reference" as only that is left there is reference documentation.
150 lines
4.7 KiB
Markdown
150 lines
4.7 KiB
Markdown
---
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title: "Introduction"
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layout: default
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sort: 1
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---
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# Introduction
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{: .no_toc}
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## Table of contents
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{: .no_toc .text-delta}
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1. TOC
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{:toc}
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---
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This software enables node feature discovery for Kubernetes. It detects
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hardware features available on each node in a Kubernetes cluster, and
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advertises those features using node labels.
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NFD consists of three software components:
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1. nfd-master
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1. nfd-worker
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1. nfd-topology-updater
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## NFD-Master
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NFD-Master is the daemon responsible for communication towards the Kubernetes
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API. That is, it receives labeling requests from the worker and modifies node
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objects accordingly.
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## NFD-Worker
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NFD-Worker is a daemon responsible for feature detection. It then communicates
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the information to nfd-master which does the actual node labeling. One
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instance of nfd-worker is supposed to be running on each node of the cluster,
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## NFD-Topology-Updater
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NFD-Topology-Updater is a daemon responsible for examining allocated
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resources on a worker node to account for resources available to be allocated
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to new pod on a per-zone basis (where a zone can be a NUMA node). It then
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communicates the information to nfd-master which does the
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[NodeResourceTopology CR](#noderesourcetopology-cr) creation corresponding
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to all the nodes in the cluster. One instance of nfd-topology-updater is
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supposed to be running on each node of the cluster.
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## Feature Discovery
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Feature discovery is divided into domain-specific feature sources:
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- CPU
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- Kernel
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- Memory
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- Network
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- PCI
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- Storage
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- System
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- USB
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- Custom (rule-based custom features)
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- Local (hooks for user-specific features)
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Each feature source is responsible for detecting a set of features which. in
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turn, are turned into node feature labels. Feature labels are prefixed with
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`feature.node.kubernetes.io/` and also contain the name of the feature source.
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Non-standard user-specific feature labels can be created with the local and
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custom feature sources.
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An overview of the default feature labels:
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```json
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{
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"feature.node.kubernetes.io/cpu-<feature-name>": "true",
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"feature.node.kubernetes.io/custom-<feature-name>": "true",
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"feature.node.kubernetes.io/kernel-<feature name>": "<feature value>",
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"feature.node.kubernetes.io/memory-<feature-name>": "true",
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"feature.node.kubernetes.io/network-<feature-name>": "true",
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"feature.node.kubernetes.io/pci-<device label>.present": "true",
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"feature.node.kubernetes.io/storage-<feature-name>": "true",
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"feature.node.kubernetes.io/system-<feature name>": "<feature value>",
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"feature.node.kubernetes.io/usb-<device label>.present": "<feature value>",
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"feature.node.kubernetes.io/<file name>-<feature name>": "<feature value>"
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}
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```
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## Node annotations
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NFD also annotates nodes it is running on:
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| Annotation | Description
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| ------------------------------------------------------------ | -----------
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| [<instance>.]nfd.node.kubernetes.io/master.version | Version of the nfd-master instance running on the node. Informative use only.
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| [<instance>.]nfd.node.kubernetes.io/worker.version | Version of the nfd-worker instance running on the node. Informative use only.
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| [<instance>.]nfd.node.kubernetes.io/feature-labels | Comma-separated list of node labels managed by NFD. NFD uses this internally so must not be edited by users.
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| [<instance>.]nfd.node.kubernetes.io/extended-resources | Comma-separated list of node extended resources managed by NFD. NFD uses this internally so must not be edited by users.
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NOTE: the [`-instance`](../reference/master-commandline-reference#instance)
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command line flag affects the annotation names
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Unapplicable annotations are not created, i.e. for example master.version is
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only created on nodes running nfd-master.
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## NodeResourceTopology CR
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When run with NFD-Topology-Updater, NFD creates CR instances corresponding to
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node resource hardware topology such as:
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```yaml
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apiVersion: topology.node.k8s.io/v1alpha1
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kind: NodeResourceTopology
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metadata:
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name: node1
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topologyPolicies: ["SingleNUMANodeContainerLevel"]
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zones:
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- name: node-0
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type: Node
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resources:
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- name: cpu
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capacity: 20
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allocatable: 16
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available: 10
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- name: vendor/nic1
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capacity: 3
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allocatable: 3
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available: 3
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- name: node-1
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type: Node
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resources:
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- name: cpu
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capacity: 30
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allocatable: 30
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available: 15
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- name: vendor/nic2
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capacity: 6
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allocatable: 6
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available: 6
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- name: node-2
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type: Node
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resources:
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- name: cpu
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capacity: 30
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allocatable: 30
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available: 15
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- name: vendor/nic1
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capacity: 3
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allocatable: 3
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available: 3
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```
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