fix: objects flagged by CurrentUIDFilter should be removed from the inventory

During pruning the code is filtering objects with `CurrentUIDFilter`:
> // CurrentUIDFilter implements ValidationFilter interface to determine
// if an object should not be pruned (deleted) because it has recently
// been applied.

This must mean that the object has ended up being tracked in the inventory by more than one reference and the one that was flagged by the filter should be removed from the inventory. Otherwise, it gets stuck in the inventory indefinitely and during every invocation of prune it'll be logged as skipped.

A good example of this is `Ingress` kind existing in both groups `extensions` and `networking.k8s.io` in k8s 1.19 & 1.20. This means when you rename the apiGroup in your local yaml to the new recommended group, then the reference with the old group name gets permastuck in the inventory.

Author: manfredlift

pkg/apply/prune/prune.go

@@ -153,6 +153,17 @@ func (p *Pruner) Prune(
 					}
 				}
 
+				// Remove the object from inventory if it was determined that the object should not be pruned,
+				// because it had recently been applied. This probably means that the object is in the inventory
+				// more than one time with a different group (e.g. kind Ingress and apiGroups networking.k8s.io & extensions)
+				var deleteAfterApplyErr *filter.ApplyPreventedDeletionError
+				if errors.As(filterErr, &deleteAfterApplyErr) {
+					if !opts.DryRunStrategy.ClientOrServerDryRun() {
+						// Register for removal from the inventory.
+						taskContext.AddAbandonedObject(id)
+					}
+				}
+
 				taskContext.SendEvent(eventFactory.CreateSkippedEvent(obj, filterErr))
 				taskContext.InventoryManager().AddSkippedDelete(id)
 				break

pkg/apply/prune/prune_test.go

@@ -325,7 +325,7 @@ func TestPrune(t *testing.T) {
 				},
 			},
 		},
-		"UID match means prune skipped": {
+		"UID match means prune skipped and object abandoned": {
 			clusterObjs: []*unstructured.Unstructured{pod},
 			pruneObjs:   []*unstructured.Unstructured{pod},
 			pruneFilters: []filter.ValidationFilter{
@@ -351,8 +351,11 @@ func TestPrune(t *testing.T) {
 			expectedSkipped: object.ObjMetadataSet{
 				object.UnstructuredToObjMetadata(pod),
 			},
+			expectedAbandoned: object.ObjMetadataSet{
+				object.UnstructuredToObjMetadata(pod),
+			},
 		},
-		"UID match for only one object one pruned, one skipped": {
+		"UID match for only one object one pruned, one skipped and abandoned": {
 			clusterObjs: []*unstructured.Unstructured{pod, pdb},
 			pruneObjs:   []*unstructured.Unstructured{pod, pdb},
 			pruneFilters: []filter.ValidationFilter{
@@ -386,6 +389,9 @@ func TestPrune(t *testing.T) {
 			expectedSkipped: object.ObjMetadataSet{
 				object.UnstructuredToObjMetadata(pod),
 			},
+			expectedAbandoned: object.ObjMetadataSet{
+				object.UnstructuredToObjMetadata(pod),
+			},
 		},
 		"Prevent delete annotation equals prune skipped": {
 			clusterObjs: []*unstructured.Unstructured{