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We now have metrics for getting detailed information about the NFD instances running. There should be no need to pollute the node object with NFD version annotations. One problem with the annotations also that they were incomplete in the sense that they only covered nfd-master and nfd-worker but not nfd-topology-updater or nfd-gc. Also, there was a problem with stale annotations, giving misleading information. E.g. there was no way to remove old/stale master.version annotations if nfd-master was scheduled on another node where it was previously running.
128 lines
4.4 KiB
Markdown
128 lines
4.4 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 and optionally node extended
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resources and node taints. Node Feature Discovery is compatible with any recent
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version of Kubernetes (v1.21+).
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NFD consists of four 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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1. nfd-gc
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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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creates or updates a
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[NodeResourceTopology](../usage/custom-resources.md#noderesourcetopology) custom
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resource object specific to this node. 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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## NFD-GC
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NFD-GC is a daemon responsible for cleaning obsolete
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[NodeFeature](../usage/custom-resources.md#nodefeature) and
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[NodeResourceTopology](../usage/custom-resources.md#noderesourcetopology) objects.
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One instance of nfd-gc is supposed to be running in 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/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.md#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
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`nfd.node.kubernetes.io/extended-resources` is only placed if some extended
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resources were created by NFD.
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## Custom resources
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NFD takes use of some Kubernetes Custom Resources.
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[NodeFeature](../usage/custom-resources.md#nodefeature)s
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is be used for representing node features and requesting node labels to be
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generated.
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NFD-Master uses [NodeFeatureRule](../usage/custom-resources.md#nodefeaturerule)s
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for custom labeling of nodes.
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NFD-Topology-Updater creates
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[NodeResourceTopology](../usage/custom-resources.md#noderesourcetopology) objects
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that describe the hardware topology of node resources.
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