🌱 Create RemoveOwnerReference function in controllerutil to remove owner references from objects

pkg/controller/controllerutil/controllerutil.go

@@ -121,6 +121,37 @@ func SetOwnerReference(owner, object metav1.Object, scheme *runtime.Scheme) erro
 	return nil
 }
 
+// RemoveOwnerReference is a helper method to make sure the given object removes an owner reference to the object provided.
+// This allows you to remove the owner to establish a new owner of the object in a subsequent call.
+func RemoveOwnerReference(owner, object metav1.Object, scheme *runtime.Scheme) error {
+	owners := object.GetOwnerReferences()
+	length := len(owners)
+	if length < 1 {
+		return fmt.Errorf("%T does not have any owner references", object)
+	}
+	ro, ok := owner.(runtime.Object)
+	if !ok {
+		return fmt.Errorf("%T is not a runtime.Object, cannot call RemoveOwnerReference", owner)
+	}
+	gvk, err := apiutil.GVKForObject(ro, scheme)
+	if err != nil {
+		return err
+	}
+
+	index := indexOwnerRef(owners, metav1.OwnerReference{
+		APIVersion: gvk.GroupVersion().String(),
+		Name:       owner.GetName(),
+		Kind:       gvk.Kind,
+	})
+	if index == -1 {
+		return fmt.Errorf("%T does not have an owner reference for %T", object, owner)
+	}
+
+	owners = append(owners[:index], owners[index+1:]...)
+	object.SetOwnerReferences(owners)
+	return nil
+}
+
 func upsertOwnerRef(ref metav1.OwnerReference, object metav1.Object) {
 	owners := object.GetOwnerReferences()
 	if idx := indexOwnerRef(owners, ref); idx == -1 {

pkg/controller/controllerutil/controllerutil_test.go

@@ -102,6 +102,99 @@ var _ = Describe("Controllerutil", func() {
 				UID:        "foo-uid-2",
 			}))
 		})
+		It("should remove the owner reference", func() {
+			rs := &appsv1.ReplicaSet{
+				ObjectMeta: metav1.ObjectMeta{
+					OwnerReferences: []metav1.OwnerReference{
+						{
+							Name:       "foo",
+							Kind:       "Deployment",
+							APIVersion: "extensions/v1alpha1",
+							UID:        "foo-uid-1",
+						},
+					},
+				},
+			}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid-2"},
+			}
+
+			Expect(controllerutil.SetOwnerReference(dep, rs, scheme.Scheme)).ToNot(HaveOccurred())
+			Expect(rs.OwnerReferences).To(ConsistOf(metav1.OwnerReference{
+				Name:       "foo",
+				Kind:       "Deployment",
+				APIVersion: "extensions/v1beta1",
+				UID:        "foo-uid-2",
+			}))
+			Expect(controllerutil.RemoveOwnerReference(dep, rs, scheme.Scheme)).ToNot(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(BeEmpty())
+		})
+		It("should remove the owner reference established by the SetControllerReference function", func() {
+			rs := &appsv1.ReplicaSet{}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid"},
+			}
+
+			Expect(controllerutil.SetControllerReference(dep, rs, scheme.Scheme)).NotTo(HaveOccurred())
+			t := true
+			Expect(rs.OwnerReferences).To(ConsistOf(metav1.OwnerReference{
+				Name:               "foo",
+				Kind:               "Deployment",
+				APIVersion:         "extensions/v1beta1",
+				UID:                "foo-uid",
+				Controller:         &t,
+				BlockOwnerDeletion: &t,
+			}))
+			Expect(controllerutil.RemoveOwnerReference(dep, rs, scheme.Scheme)).NotTo(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(BeEmpty())
+		})
+		It("should error when trying to remove the reference that doesn't exist", func() {
+			rs := &appsv1.ReplicaSet{
+				ObjectMeta: metav1.ObjectMeta{},
+			}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid-2"},
+			}
+			Expect(controllerutil.RemoveOwnerReference(dep, rs, scheme.Scheme)).To(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(BeEmpty())
+		})
+		It("should error when trying to remove the reference that doesn't abide by the scheme", func() {
+			rs := &appsv1.ReplicaSet{
+				ObjectMeta: metav1.ObjectMeta{},
+			}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid-2"},
+			}
+			Expect(controllerutil.SetOwnerReference(dep, rs, scheme.Scheme)).ToNot(HaveOccurred())
+			Expect(controllerutil.RemoveOwnerReference(dep, rs, runtime.NewScheme())).To(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(HaveLen(1))
+		})
+		It("should error when trying to remove the owner when setting the owner as a non runtime.Object", func() {
+			var obj metav1.Object
+			rs := &appsv1.ReplicaSet{
+				ObjectMeta: metav1.ObjectMeta{},
+			}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid-2"},
+			}
+			Expect(controllerutil.SetOwnerReference(dep, rs, scheme.Scheme)).ToNot(HaveOccurred())
+			Expect(controllerutil.RemoveOwnerReference(obj, rs, scheme.Scheme)).To(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(HaveLen(1))
+		})
+		It("should error when trying to remove an owner that doesn't exist", func() {
+			rs := &appsv1.ReplicaSet{
+				ObjectMeta: metav1.ObjectMeta{},
+			}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid-2"},
+			}
+			dep2 := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "bar", UID: "bar-uid-3"},
+			}
+			Expect(controllerutil.SetOwnerReference(dep, rs, scheme.Scheme)).ToNot(HaveOccurred())
+			Expect(controllerutil.RemoveOwnerReference(dep2, rs, scheme.Scheme)).To(HaveOccurred())
+			Expect(rs.GetOwnerReferences()).To(HaveLen(1))
+		})
 	})
 
 	Describe("SetControllerReference", func() {