✨ Allow to use builder.OnlyMetadata option with Watches

This change allows builders to use builder.OnlyMetadata when creating
extra watches with .Watches(...). The code inspects the passed
source.Source, and if it's of type *source.Kind, it calls the internal
project method that allows to use metav1.PartialObjectMetadata in
mapping functions.

Signed-off-by: Vince Prignano <vincepri@vmware.com>

pkg/builder/controller.go

@@ -116,9 +116,10 @@ func (blder *Builder) Owns(object client.Object, opts ...OwnsOption) *Builder {
 
 // WatchesInput represents the information set by Watches method.
 type WatchesInput struct {
-	src          source.Source
-	eventhandler handler.EventHandler
-	predicates   []predicate.Predicate
+	src              source.Source
+	eventhandler     handler.EventHandler
+	predicates       []predicate.Predicate
+	objectProjection objectProjection
 }
 
 // Watches exposes the lower-level ControllerManagedBy Watches functions through the builder.  Consider using
@@ -255,10 +256,19 @@ func (blder *Builder) doWatch() error {
 	for _, w := range blder.watchesInput {
 		allPredicates := append([]predicate.Predicate(nil), blder.globalPredicates...)
 		allPredicates = append(allPredicates, w.predicates...)
+
+		// If the source of this watch is of type *source.Kind, project it.
+		if srckind, ok := w.src.(*source.Kind); ok {
+			typeForSrc, err := blder.project(srckind.Type, w.objectProjection)
+			if err != nil {
+				return err
+			}
+			srckind.Type = typeForSrc
+		}
+
 		if err := blder.ctrl.Watch(w.src, w.eventhandler, allPredicates...); err != nil {
 			return err
 		}
-
 	}
 	return nil
 }

pkg/builder/controller_test.go

@@ -371,14 +371,61 @@ var _ = Describe("application", func() {
 			Expect(err).NotTo(HaveOccurred())
 		})
 
-		It("should support watching For & Owns as metadata", func() {
+		It("should support watching For, Owns, and Watch as metadata", func() {
+			statefulSetMaps := make(chan *metav1.PartialObjectMetadata)
+
 			bldr := ControllerManagedBy(mgr).
 				For(&appsv1.Deployment{}, OnlyMetadata).
-				Owns(&appsv1.ReplicaSet{}, OnlyMetadata)
+				Owns(&appsv1.ReplicaSet{}, OnlyMetadata).
+				Watches(&source.Kind{Type: &appsv1.StatefulSet{}},
+					handler.EnqueueRequestsFromMapFunc(func(o client.Object) []reconcile.Request {
+						ometa := o.(*metav1.PartialObjectMetadata)
+						statefulSetMaps <- ometa
+						return nil
+					}),
+					OnlyMetadata)
 
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
 			doReconcileTest(ctx, "8", bldr, mgr, true)
+
+			By("Creating a new stateful set")
+			set := &appsv1.StatefulSet{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: "default",
+					Name:      "test1",
+					Labels: map[string]string{
+						"foo": "bar",
+					},
+				},
+				Spec: appsv1.StatefulSetSpec{
+					Selector: &metav1.LabelSelector{
+						MatchLabels: map[string]string{"foo": "bar"},
+					},
+					Template: corev1.PodTemplateSpec{
+						ObjectMeta: metav1.ObjectMeta{Labels: map[string]string{"foo": "bar"}},
+						Spec: corev1.PodSpec{
+							Containers: []corev1.Container{
+								{
+									Name:  "nginx",
+									Image: "nginx",
+								},
+							},
+						},
+					},
+				},
+			}
+			err := mgr.GetClient().Create(context.TODO(), set)
+			Expect(err).NotTo(HaveOccurred())
+
+			By("Checking that the mapping function has been called")
+			Eventually(func() bool {
+				metaSet := <-statefulSetMaps
+				Expect(metaSet.Name).To(Equal(set.Name))
+				Expect(metaSet.Namespace).To(Equal(set.Namespace))
+				Expect(metaSet.Labels).To(Equal(set.Labels))
+				return true
+			}).Should(BeTrue())
 		})
 	})
 })

pkg/builder/options.go

@@ -94,6 +94,11 @@ func (p projectAs) ApplyToOwns(opts *OwnsInput) {
 	opts.objectProjection = objectProjection(p)
 }
 
+// ApplyToWatches applies this configuration to the given WatchesInput options.
+func (p projectAs) ApplyToWatches(opts *WatchesInput) {
+	opts.objectProjection = objectProjection(p)
+}
+
 var (
 	// OnlyMetadata tells the controller to *only* cache metadata, and to watch
 	// the the API server in metadata-only form.  This is useful when watching
@@ -104,8 +109,9 @@ var (
 	// unstructured cache.
 	OnlyMetadata = projectAs(projectAsMetadata)
 
-	_ ForOption  = OnlyMetadata
-	_ OwnsOption = OnlyMetadata
+	_ ForOption     = OnlyMetadata
+	_ OwnsOption    = OnlyMetadata
+	_ WatchesOption = OnlyMetadata
 )
 
 // }}}