[ClusterClass Operations] Implementation

[richardcase]

Description

This epic is used to track the implementation of the #353 proposal. Details on the proposal can be found here.

Issues

• Scaffolding: add basic ClusterClass scaffolding to ./exp: [ClusterClass Operations] Scaffolding #850
  • Keep functionality behind feature gate.
• Rebase: apply Class changes to one/many clusters and provide mechanisms to perform updates in a controlled manner.
  • Controller watching ClusterUpgradeGroup [ClusterClass Operations] Add rebase controller #638
  • E2E [ClusterClass Operations] Cover rebase in E2E tests #639
  • Scheduling [ClusterClass Operations] Support scheduling on rebase operations #642
• Versioning: support classifying Class objects as versions of the same template.
  • Represent Class objects in Rancher by annotations' values: name/version [ClusterClass Operations] Add version control to ClusterClass #641
• Kubernetes version management: based on ClusterUpgradeGroup.
  • E2E [ClusterClass Operations] Cover k8s version update in E2E tests #643

Related issues

• Using ClusterClass from different namespaces Investigate using ClusterClass from a different namespace highlander#53.
  • Ongoing discussion upstream to support cross-namespace Class/Clusters.