interface: CRP API change to support multiple resourceSnapshot versions across clusters

Signed-off-by: Wantong Jiang <wantjian@microsoft.com>

Author: jwtty

apis/placement/v1beta1/clusterresourceplacement_types.go

@@ -822,6 +822,9 @@ type ClusterResourcePlacementStatus struct {
 	// One resource snapshot can contain multiple clusterResourceSnapshots CRs in order to store large amount of resources.
 	// To get clusterResourceSnapshot of a given resource index, use the following command:
 	// `kubectl get ClusterResourceSnapshot --selector=kubernetes-fleet.io/resource-index=$ObservedResourceIndex `
+	// During rollout, clusters may run different versions of the resource snapshot concurrently.
+	// In this case, ObservedResourceIndex represents the index of the latest resource snapshot installed across all clusters.
+	// Note that this may differ from the index of the latest resource snapshot available in the hub cluster depending on the rollout strategy.
 	// ObservedResourceIndex is the resource index that the conditions in the ClusterResourcePlacementStatus observe.
 	// For example, a condition of `ClusterResourcePlacementWorkSynchronized` type
 	// is observing the synchronization status of the resource snapshot with the resource index $ObservedResourceIndex.
@@ -954,6 +957,13 @@ type ResourcePlacementStatus struct {
 	// +kubebuilder:validation:MaxItems=100
 	DiffedPlacements []DiffedResourcePlacement `json:"diffedPlacements,omitempty"`
 
+	// ObservedResourceIndex is the index of the resource snapshot that is currently rolled out on the given cluster.
+	// During rollout, depending on the rollout strategy, clusters may observe different resource indices.
+	// ObservedResourceIndex is the resource snapshot index observed by the conditions in the ResourcePlacementStatus.
+	// This field is only meaningful if the `ClusterName` is not empty.
+	// +kubebuilder:validation:Optional
+	ObservedResourceIndex string `json:"observedResourceIndex,omitempty"`
+
 	// Conditions is an array of current observed conditions for ResourcePlacementStatus.
 	// +kubebuilder:validation:Optional
 	Conditions []metav1.Condition `json:"conditions,omitempty"`

config/crd/bases/placement.kubernetes-fleet.io_clusterresourceplacements.yaml

@@ -2044,6 +2044,9 @@ spec:
                   One resource snapshot can contain multiple clusterResourceSnapshots CRs in order to store large amount of resources.
                   To get clusterResourceSnapshot of a given resource index, use the following command:
                   `kubectl get ClusterResourceSnapshot --selector=kubernetes-fleet.io/resource-index=$ObservedResourceIndex `
+                  During rollout, clusters may run different versions of the resource snapshot concurrently.
+                  In this case, ObservedResourceIndex represents the index of the latest resource snapshot installed across all clusters.
+                  Note that this may differ from the index of the latest resource snapshot available in the hub cluster depending on the rollout strategy.
                   ObservedResourceIndex is the resource index that the conditions in the ClusterResourcePlacementStatus observe.
                   For example, a condition of `ClusterResourcePlacementWorkSynchronized` type
                   is observing the synchronization status of the resource snapshot with the resource index $ObservedResourceIndex.
@@ -2500,6 +2503,13 @@ spec:
                         type: object
                       maxItems: 100
                       type: array
+                    observedResourceIndex:
+                      description: |-
+                        ObservedResourceIndex is the index of the resource snapshot that is currently rolled out on the given cluster.
+                        During rollout, depending on the rollout strategy, clusters may observe different resource indices.
+                        ObservedResourceIndex is the resource snapshot index observed by the conditions in the ResourcePlacementStatus.
+                        This field is only meaningful if the `ClusterName` is not empty.
+                      type: string
                   type: object
                 type: array
               selectedResources: