Return a DiffTypeExclude when exclusion annotation is set in cluster

We want to enable this behaviour for use cases where different
controllers must coordinate in order to mutate a resource.

Signed-off-by: Soule BA <[email protected]>

ssa/jsondiff/unstructured.go

@@ -137,6 +137,11 @@ func Unstructured(ctx context.Context, c client.Client, obj *unstructured.Unstru
 		return nil, err
 	}
 
+	// Short-circuit if an annotation is set to ignore the resource in-cluster.
+	if utils.AnyInMetadata(existingObj, o.ExclusionSelector) {
+		return NewDiffForUnstructured(obj, nil, DiffTypeExclude, nil), nil
+	}
+
 	dryRunObj := obj.DeepCopy()
 	patchOpts := []client.PatchOption{
 		client.DryRunAll,

ssa/jsondiff/unstructured_test.go

@@ -175,6 +175,43 @@ func TestUnstructuredList(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "excludes resources with matching annotation set in the cluster",
+			paths: []string{
+				"testdata/deployment.yaml",
+				"testdata/service.yaml",
+			},
+			mutateCluster: func(obj *unstructured.Unstructured) {
+				if obj.GetKind() != "Service" {
+					return
+				}
+
+				annotations := obj.GetAnnotations()
+				if annotations == nil {
+					annotations = make(map[string]string)
+				}
+				annotations["exclude"] = "enabled"
+				obj.SetAnnotations(annotations)
+
+				_ = unstructured.SetNestedField(obj.Object, "NodePort", "spec", "type")
+			},
+			opts: []ListOption{
+				ExclusionSelector{"exclude": "enabled"},
+			},
+			want: func(desired, cluster []*unstructured.Unstructured) DiffSet {
+				return DiffSet{
+					&Diff{
+						Type:          DiffTypeNone,
+						DesiredObject: desired[0],
+						ClusterObject: cluster[0],
+					},
+					&Diff{
+						Type:          DiffTypeExclude,
+						DesiredObject: desired[1],
+					},
+				}
+			},
+		},
 		{
 			name: "ignores JSON pointers for resources matching selector",
 			paths: []string{