add function to controllerutil RemoveControllerReference

Signed-off-by: Troy Connor <troy0820@users.noreply.github.com>

pkg/controller/controllerutil/controllerutil.go

@@ -91,6 +91,27 @@ func SetControllerReference(owner, controlled metav1.Object, scheme *runtime.Sch
 	return nil
 }
 
+// RemoveControllerReference is a helper method to make sure the given object removes an controller 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 RemoveControllerReference(owner, controlled metav1.Object) error {
+	owners := controlled.GetOwnerReferences()
+	length := len(owners)
+	if length < 1 {
+		return fmt.Errorf("%T does not have any owner references", controlled)
+	}
+	index := 0
+	for i := 0; i < length; i++ {
+		if owners[i].Name == owner.GetName() {
+			owners = append(owners[:index], owners[index+1:]...)
+		}
+		index++
+	}
+	if length == len(owners) {
+		return fmt.Errorf("%T does not have an owner reference for %T", controlled, owner)
+	}
+	return nil
+}
+
 // SetOwnerReference is a helper method to make sure the given object contains an object reference to the object provided.
 // This allows you to declare that owner has a dependency on the object without specifying it as a controller.
 // If a reference to the same object already exists, it'll be overwritten with the newly provided version.

pkg/controller/controllerutil/controllerutil_test.go

@@ -103,7 +103,6 @@ var _ = Describe("Controllerutil", func() {
 			}))
 		})
 	})
-
 	Describe("SetControllerReference", func() {
 		It("should set the OwnerReference if it can find the group version kind", func() {
 			rs := &appsv1.ReplicaSet{}
@@ -256,6 +255,46 @@ var _ = Describe("Controllerutil", func() {
 			}))
 		})
 	})
+	Describe("RemoveControllerReference", func() {
+		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.RemoveControllerReference(dep, rs)).NotTo(HaveOccurred())
+		})
+		It("should fail and return an error if the length is less than 1", func() {
+			rs := &appsv1.ReplicaSet{}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid"},
+			}
+			Expect(controllerutil.RemoveControllerReference(dep, rs)).To(HaveOccurred())
+		})
+		It("should fail and return an error because the owner doesn't exist to remove", func() {
+			rs := &appsv1.ReplicaSet{}
+			dep := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "foo", UID: "foo-uid"},
+			}
+			dep2 := &extensionsv1beta1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{Name: "bar", UID: "bar-uid"},
+			}
+			Expect(controllerutil.SetControllerReference(dep, rs, scheme.Scheme)).NotTo(HaveOccurred())
+			Expect(controllerutil.RemoveControllerReference(dep2, rs)).To(HaveOccurred())
+		})
+
+	})
 
 	Describe("CreateOrUpdate", func() {
 		var deploy *appsv1.Deployment