Node Feature Discovery

# NFD-Topology-Updater

NFD-Topology-Updater is preferably run as a Kubernetes DaemonSet. This assures re-examination on regular intervals and/or per pod life-cycle events, capturing changes in the allocated resources and hence the allocatable resources on a per-zone basis by updating NodeResourceTopology custom resources. It makes sure that new NodeResourceTopology instances are created for each new nodes that get added to the cluster.

Because of the design and implementation of Kubernetes, only resources exclusively allocated to Guaranteed Quality of Service pods will be accounted. This includes CPU cores, memory and devices.

When run as a daemonset, nodes are re-examined for the allocated resources (to determine the information of the allocatable resources on a per-zone basis where a zone can be a NUMA node) at an interval specified using the `-sleep-interval` option. The default sleep interval is set to 60s which is the value when no -sleep-interval is specified. The re-examination can be disabled by setting the sleep-interval to 0.

Another option is to configure the updater to update the allocated resources per pod life-cycle events. The updater will monitor the checkpoint file stated in `-kubelet-state-dir` and triggers an update for every change occurs in the files.

In addition, it can avoid examining specific allocated resources given a configuration of resources to exclude via `-excludeList`

## Deployment Notes

Kubelet PodResource API with the GetAllocatableResources functionality enabled is a prerequisite for nfd-topology-updater to be able to run (i.e. Kubernetes v1.21 or later is required).

Preceding Kubernetes v1.23, the `kubelet` must be started with `--feature-gates=KubeletPodResourcesGetAllocatable=true`.

Starting from Kubernetes v1.23, the `KubeletPodResourcesGetAllocatable` feature gate. is enabled by default

## Topology-Updater Configuration

NFD-Topology-Updater supports configuration through a configuration file. The default location is `/etc/kubernetes/node-feature-discovery/topology-updater.conf`, but, this can be changed by specifying the`-config` command line flag.

> NOTE: unlike nfd-worker, dynamic configuration updates are not currently supported.

Topology-Updater configuration file is read inside the container, and thus, Volumes and VolumeMounts are needed to make your configuration available for NFD. The preferred method is to use a ConfigMap which provides easy deployment and re-configurability.

The provided nfd-topology-updater deployment templates create an empty configmap and mount it inside the nfd-topology-updater containers. In kustomize deployments, configuration can be edited with:

    kubectl -n ${NFD_NS} edit configmap nfd-topology-updater-conf

In Helm deployments, Topology Updater parameters `toplogyUpdater.config` can be used to edit the respective configuration.

See nfd-topology-updater configuration file reference for more details. The (empty-by-default) example config contains all available configuration options and can be used as a reference for creating a configuration.

Node Feature Discovery
v0.14

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This Software is under the terms of Apache License 2.0.