From e6a8bb57e868eec5184881e1e3f4f9991f1232aa Mon Sep 17 00:00:00 2001
From: Tom Pantelis <tompantelis@gmail.com>
Date: Wed, 17 Apr 2024 08:25:22 -0400
Subject: [PATCH] Add reusable TrimManagedFields transform function

Signed-off-by: Tom Pantelis <tompantelis@gmail.com>
---
 pkg/resource/resource_test.go | 61 +++++++++++++++++++++++++++++++++++
 pkg/resource/util.go          | 11 +++++++
 pkg/syncer/resource_syncer.go |  9 +-----
 3 files changed, 73 insertions(+), 8 deletions(-)

diff --git a/pkg/resource/resource_test.go b/pkg/resource/resource_test.go
index 38c40831..fd869b2d 100644
--- a/pkg/resource/resource_test.go
+++ b/pkg/resource/resource_test.go
@@ -22,6 +22,10 @@ import (
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	"github.com/submariner-io/admiral/pkg/resource"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/utils/ptr"
 )
 
 var _ = Describe("EnsureValidName", func() {
@@ -44,3 +48,60 @@ var _ = Describe("EnsureValidName", func() {
 		})
 	})
 })
+
+var _ = Describe("TrimManagedFields", func() {
+	pod := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:        "pod",
+			Namespace:   "ns",
+			Labels:      map[string]string{"app": "test"},
+			Annotations: map[string]string{"foo": "bar"},
+		},
+		Spec: corev1.PodSpec{
+			Containers: []corev1.Container{
+				{
+					Image: "image",
+					Name:  "httpd",
+				},
+			},
+		},
+	}
+
+	When("the object has metadata", func() {
+		It("should succeed and trim the ManagedFields", func() {
+			podWithMF := pod.DeepCopy()
+			podWithMF.ManagedFields = []metav1.ManagedFieldsEntry{
+				{
+					Manager:    "kubectl",
+					Operation:  metav1.ManagedFieldsOperationApply,
+					APIVersion: "v1",
+					Time:       ptr.To(metav1.Now()),
+					FieldsType: "FieldsV1",
+					FieldsV1:   ptr.To(metav1.FieldsV1{}),
+				},
+			}
+
+			retObj, err := resource.TrimManagedFields(podWithMF)
+			Expect(err).To(Succeed())
+			Expect(podWithMF).To(Equal(pod))
+			Expect(retObj).To(BeIdenticalTo(podWithMF))
+
+			_, err = resource.TrimManagedFields(podWithMF)
+			Expect(err).To(Succeed())
+			Expect(podWithMF).To(Equal(pod))
+		})
+	})
+
+	When("the object does not have metadata", func() {
+		It("should succeed and return the object", func() {
+			obj := &cache.DeletedFinalStateUnknown{
+				Key: "key",
+				Obj: pod,
+			}
+
+			retObj, err := resource.TrimManagedFields(obj)
+			Expect(err).To(Succeed())
+			Expect(retObj).To(Equal(obj))
+		})
+	})
+})
diff --git a/pkg/resource/util.go b/pkg/resource/util.go
index 54054fcc..af861b91 100644
--- a/pkg/resource/util.go
+++ b/pkg/resource/util.go
@@ -125,3 +125,14 @@ func ToJSON(o any) string {
 	out, _ := json.MarshalIndent(o, "", "  ")
 	return string(out)
 }
+
+// TrimManagedFields is a cache.TransformFunc that removes the ManagedFields metadata field if present. Note that if 'obj' does not
+// implement metav1.Object then it is ignored and no error is returned.
+func TrimManagedFields(obj interface{}) (interface{}, error) {
+	objMeta, err := meta.Accessor(obj)
+	if err == nil && len(objMeta.GetManagedFields()) > 0 {
+		objMeta.SetManagedFields(nil)
+	}
+
+	return obj, nil
+}
diff --git a/pkg/syncer/resource_syncer.go b/pkg/syncer/resource_syncer.go
index ae05325a..ad0f6990 100644
--- a/pkg/syncer/resource_syncer.go
+++ b/pkg/syncer/resource_syncer.go
@@ -256,14 +256,7 @@ func NewResourceSyncer(config *ResourceSyncerConfig) (Interface, error) {
 		AddFunc:    syncer.onCreate,
 		UpdateFunc: syncer.onUpdate,
 		DeleteFunc: syncer.onDelete,
-	}, func(obj interface{}) (interface{}, error) {
-		objMeta, err := meta.Accessor(obj)
-		if err == nil && len(objMeta.GetManagedFields()) > 0 {
-			objMeta.SetManagedFields(nil)
-		}
-
-		return obj, nil
-	})
+	}, resourceUtil.TrimManagedFields)
 
 	return syncer, nil
 }