From a5feeb69455334ad4b0c25a6da5e13f6d41aabb2 Mon Sep 17 00:00:00 2001
From: Axel Christ <axel.christ@sap.com>
Date: Wed, 23 Feb 2022 09:07:53 +0100
Subject: [PATCH] Implement metautils.IsControlledBy

---
 metautils/metautils.go      | 28 ++++++++++++
 metautils/metautils_test.go | 89 +++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)

diff --git a/metautils/metautils.go b/metautils/metautils.go
index 913dd64..b1234f5 100644
--- a/metautils/metautils.go
+++ b/metautils/metautils.go
@@ -16,12 +16,15 @@
 package metautils
 
 import (
+	"fmt"
 	"reflect"
 	"strings"
 
 	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 )
 
@@ -68,3 +71,28 @@ func ListElementType(list runtime.Object) (reflect.Type, error) {
 	v := reflect.ValueOf(itemsPtr)
 	return v.Type().Elem().Elem(), nil
 }
+
+// IsControlledBy checks if controlled is controlled by owner.
+// An object is considered to be controlled if there is a controller (via metav1.GetControllerOf) whose
+// GVK, name and UID match with the controller object.
+func IsControlledBy(scheme *runtime.Scheme, owner, controlled client.Object) (bool, error) {
+	controller := metav1.GetControllerOf(controlled)
+	if controller == nil {
+		return false, nil
+	}
+
+	gvk, err := apiutil.GVKForObject(owner, scheme)
+	if err != nil {
+		return false, fmt.Errorf("error getting object kinds of owner: %w", err)
+	}
+
+	gv, err := schema.ParseGroupVersion(controller.APIVersion)
+	if err != nil {
+		return false, fmt.Errorf("could not parse controller api version: %w", err)
+	}
+
+	return gvk.GroupVersion() == gv &&
+		controller.Kind == gvk.Kind &&
+		controller.Name == owner.GetName() &&
+		controller.UID == owner.GetUID(), nil
+}
diff --git a/metautils/metautils_test.go b/metautils/metautils_test.go
index 5f61189..951fda1 100644
--- a/metautils/metautils_test.go
+++ b/metautils/metautils_test.go
@@ -22,9 +22,12 @@ import (
 	. "github.com/onsi/gomega"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes/scheme"
+	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 )
 
 var _ = Describe("Metautils", func() {
@@ -81,4 +84,90 @@ var _ = Describe("Metautils", func() {
 			)).To(HaveOccurred())
 		})
 	})
+
+	Describe("IsControlledBy", func() {
+		It("should report true if the object is controlled by another", func() {
+			By("making a controlling object")
+			owner := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "owner",
+					UID:       types.UID("owner-uuid"),
+				},
+			}
+
+			By("making an object to be controlled")
+			owned := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "owned",
+					UID:       types.UID("owned-uuid"),
+				},
+			}
+
+			By("setting the controller reference")
+			Expect(controllerutil.SetControllerReference(owner, owned, scheme.Scheme)).To(Succeed())
+
+			By("asserting the object reports as controlled")
+			Expect(IsControlledBy(scheme.Scheme, owner, owned)).To(BeTrue(), "object should be controlled by owner, object: %#v, owner: %#v", owned, owner)
+		})
+
+		It("should report false if the object is not controlled by another", func() {
+			By("making two regular objects")
+			obj1 := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "obj1",
+					UID:       types.UID("obj1-uuid"),
+				},
+			}
+			obj2 := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "obj2",
+					UID:       types.UID("obj2-uuid"),
+				},
+			}
+
+			By("asserting the object does not report as controlled")
+			Expect(IsControlledBy(scheme.Scheme, obj1, obj2)).To(BeFalse(), "object should not be controlled, obj1: %#v, obj2: %#v", obj1, obj2)
+		})
+
+		It("should error if it cannot determine the gvk of an object", func() {
+			By("creating an object whose type is not registered in the default scheme")
+			obj1 := &struct{ corev1.ConfigMap }{
+				ConfigMap: corev1.ConfigMap{
+					ObjectMeta: metav1.ObjectMeta{
+						Namespace: corev1.NamespaceDefault,
+						Name:      "obj1",
+						UID:       types.UID("obj1-uuid"),
+					},
+				},
+			}
+
+			By("making a controlling object")
+			owner := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "owner",
+					UID:       types.UID("owner-uuid"),
+				},
+			}
+
+			By("making a regular object")
+			owned := &corev1.ConfigMap{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: corev1.NamespaceDefault,
+					Name:      "owned",
+					UID:       types.UID("owned-uuid"),
+				},
+			}
+
+			By("setting the controller for owned")
+			Expect(controllerutil.SetControllerReference(owner, owned, scheme.Scheme)).To(Succeed())
+
+			_, err := IsControlledBy(scheme.Scheme, obj1, owned)
+			Expect(err).To(HaveOccurred())
+		})
+	})
 })