clusterset delete policy

enhancements/sig-architecture/34-clusterset-delete/README.md

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+# ManagedClusterSet Delete policy
+
+## Release Signoff Checklist
+- [ ] Enhancement is `implementable`
+- [ ] Design details are appropriately documented from clear requirements
+- [ ] Test plan is defined
+- [ ] Graduation criteria for dev preview, tech preview, GA
+- [ ] User-facing documentation is created in [website](https://github.com/open-cluster-management/website/)
+
+## Summary
+The proposed work enhances the managedClusterSet API to handle managedClusterSet Delete policy.
+
+## Motivation
+Currently, when we add a cluster to a clusterset, we will add a label `cluster.open-cluster-management.io/clusterset:<Clusterset Name>` to the cluster. But when the clusterset is deleted, this label will not be removed.
+
+So we need to design the delete policy for clusterset.
+
+## Proposal Detail
+Actually, we always use clusterset as a group of clusters. So when deleting a clusterset, there are some options for the delete policy.
+1. When clusterset deleted, delete the clusterset labels in managedClusters.
+2. When clusterset deleted, delete the managedClusters in clusterset.
+3. Hold the clusterset deletion if there are clusters in the set.
+
+### API Change
+We add a new field `DeletePolicy` in `ManagedClusterSetSpec`.
+
+```go
+type ManagedClusterSetSpec struct {
+   // Selector represents a selector of ManagedClusters.
+   ClusterSelector ManagedClusterSelector  `json:"clusterSelector"`
+
+   // Only works for the ClusterSelector.SelectorType is "LegacyClusterSetLabel"
+   // +optional
+   DeletePolicy DeletePolicyType
+}
+
+type DeletePolicyType string
+
+type ManagedClusterSelector struct{
+   SelectorType SelectorType `json:"selectorType"`
+}
+
+type SelectorType string
+
+const (
+   LegacyClusterSetLabel SelectorType = "LegacyClusterSetLabel"
+)
+
+const (
+   DeleteClusterSetLabel       DeletePolicyType = "DeleteClusterSetLabel"
+   HoldClusterSetDeletion      DeletePolicyType = "HoldClusterSetDeletion"
+   DeleteClusters              DeletePolicyType = "DeleteClusters"
+)
+
+```
+### Details
+Notes: the `DeletePolicy` only works for the `ClusterSelector.SelectorType` is `LegacyClusterSetLabel`. It means the clusterset uses the label `cluster.open-cluster-management.io/clusterset:<Clusterset Name>` to select target clusters. So In the doc, we only cover the clusterset which `ClusterSelector.SelectorType` is `LegacyClusterSetLabel`
+There are some options to delete a clusterset.
+
+1. DeleteClusterSetLabel
+In each managed cluster in a clusterset, it should have a label `cluster.open-cluster-management.io/clusterset:<Clusterset Name>`. When the clusterset is deleted. This label is useless. So we could delete the label in each managedClusters when the clusterset is deleted.
+
+2. HoldClusterSetDeletion
+In this option, when a clusterset is deleted, if there still have clusters in this set, we will hold the clusterset deletion.
+
+3. DeleteClusters
+In this option, when a clusterset is deleted, we will delete all clusters in this set.
+
+4. ""
+As this field is optional, so if the value is "", we will only delete the clusterset, and all other related resources will remain.
+
+## Upgrade / Downgrade Strategy
+The new api is compatible with the previous version. So there is no external work needed when upgrading

enhancements/sig-architecture/34-clusterset-delete/metadata.yaml

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+title: update-managedcluster-status-to-include-clusterinfo
+authors:
+  - "@ldpliu"
+reviewers:
+  - "@qiujian16"
+  - "@elgnay"
+approvers:
+  - "@qiujian16"
+  - "@elgnay"
+  - "@deads2k"
+creation-date: 2022-4-22
+last-updated: 2022-04-22
+status: provisional