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ClusterSet

ClusterSet represents a specific pattern implemented by various organizations. A ClusterSet is typically:

  • A group of clusters governed by a single authority.
  • There is usually a high degree of trust within the set of clusters.
  • Namespace Sameness applies to clusters in the set:
    • Permissions and characteristics are consistent across clusters for a given namespace.
    • Namespaces don't have to exist in every cluster, but behave the same across those in which they do.

Note

The early definition of the ClusterSet was described in KEP-2149. It is now part of the About API.

A cluster's ClusterSet membership is stored in the about.k8s.io/ClusterProperty clusterset.k8s.io.

Cluster Metadata

The ClusterSet is a Cluster-scoped ClusterProperty CRD (Customer Resource Definition), that stores a name and a value.

This property can be used to:

  • uniquely identify clusters using a clusterID

    apiVersion: about.k8s.io/v1
kind: ClusterProperty
metadata:
    name: cluster.clusterset.k8s.io
spec:
    value: cluster-1

  • uniquely identify the membership of a cluster in a ClusterSet for the lifetime of the membership.

    apiVersion: about.k8s.io/v1
kind: ClusterProperty
metadata:
    name: clusterset.k8s.io
spec:
    value: mycoolclusterset

  • Provide a reference point for multi-cluster tooling to build on within a cluster set, for example for DNS labels, for logging and tracing, etc.

  • Provide extra metadata space to store other cluster properties that might otherwise be implemented as ad-hoc annotations on semantically adjacent objects.

    apiVersion: about.k8s.io/v1
kind: ClusterProperty
metadata:
    name: fingerprint.mycoolimplementation.com
spec:
    value:  '{"major": "1","minor": "18","gitVersion": "v1.18.2","gitCommit": "52c56ce7a8272c798dbc29846288d7cd9fbae032","gitTreeState": "clean","buildDate": "2020-04-30T20:19:45Z","goVersion": "go1.13.9","compiler": "gc","platform": "linux/amd64"}'