Only update managedFields on update if it already exists

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/BUILD

@@ -47,6 +47,7 @@ go_test(
         "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/api/meta:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager.go

@@ -104,6 +104,10 @@ func (f *FieldManager) Update(liveObj, newObj runtime.Object, manager string) (r
 			return nil, fmt.Errorf("failed to decode managed fields: %v", err)
 		}
 	}
+	// if managed field is still empty, skip updating managed fields altogether
+	if len(managed.Fields) == 0 {
+		return newObj, nil
+	}
 	newObjVersioned, err := f.toVersioned(newObj)
 	if err != nil {
 		return nil, fmt.Errorf("failed to convert new object to proper version: %v", err)
@@ -165,9 +169,11 @@ func (f *FieldManager) Update(liveObj, newObj runtime.Object, manager string) (r
 // object and update the managed fields.
 func (f *FieldManager) Apply(liveObj runtime.Object, patch []byte, fieldManager string, force bool) (runtime.Object, error) {
 	// If the object doesn't have metadata, apply isn't allowed.
-	if _, err := meta.Accessor(liveObj); err != nil {
+	accessor, err := meta.Accessor(liveObj)
+	if err != nil {
 		return nil, fmt.Errorf("couldn't get accessor: %v", err)
 	}
+	missingManagedFields := (len(accessor.GetManagedFields()) == 0)
 
 	managed, err := internal.DecodeObjectManagedFields(liveObj)
 	if err != nil {
@@ -207,6 +213,23 @@ func (f *FieldManager) Apply(liveObj runtime.Object, patch []byte, fieldManager
 	}
 
 	apiVersion := fieldpath.APIVersion(f.groupVersion.String())
+	// if managed field is missing, create a single entry for all the fields
+	if missingManagedFields {
+		unknownManager, err := internal.BuildManagerIdentifier(&metav1.ManagedFieldsEntry{
+			Manager:    "before-first-apply",
+			Operation:  metav1.ManagedFieldsOperationUpdate,
+			APIVersion: f.groupVersion.String(),
+		})
+		if err != nil {
+			return nil, fmt.Errorf("failed to create manager for existing fields: %v", err)
+		}
+		unknownFieldSet, err := liveObjTyped.ToFieldSet()
+		if err != nil {
+			return nil, fmt.Errorf("failed to create fieldset for existing fields: %v", err)
+		}
+		managed.Fields[unknownManager] = fieldpath.NewVersionedSet(unknownFieldSet, apiVersion, false)
+		f.stripFields(managed.Fields, unknownManager)
+	}
 	newObjTyped, managedFields, err := f.updater.Apply(liveObjTyped, patchObjTyped, apiVersion, managed.Fields, manager, force)
 	if err != nil {
 		if conflicts, ok := err.(merge.Conflicts); ok {

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager_test.go

@@ -25,6 +25,7 @@ import (
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
+	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/runtime/schema"
@@ -75,6 +76,7 @@ func TestApplyStripsFields(t *testing.T) {
 	f := NewTestFieldManager()
 
 	obj := &corev1.Pod{}
+	obj.ObjectMeta.ManagedFields = []metav1.ManagedFieldsEntry{{}}
 
 	newObj, err := f.Apply(obj, []byte(`{
 		"apiVersion": "apps/v1",
@@ -153,6 +155,7 @@ func TestApplyDoesNotStripLabels(t *testing.T) {
 	f := NewTestFieldManager()
 
 	obj := &corev1.Pod{}
+	obj.ObjectMeta.ManagedFields = []metav1.ManagedFieldsEntry{{}}
 
 	newObj, err := f.Apply(obj, []byte(`{
 		"apiVersion": "apps/v1",

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/patch.go

@@ -421,7 +421,7 @@ func (p *applyPatcher) applyPatchToCurrentObject(obj runtime.Object) (runtime.Ob
 func (p *applyPatcher) createNewObject() (runtime.Object, error) {
 	obj, err := p.creater.New(p.kind)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create new object: %v", obj)
+		return nil, fmt.Errorf("failed to create new object: %v", err)
 	}
 	return p.applyPatchToCurrentObject(obj)
 }

test/integration/apiserver/apply/apply_test.go

@@ -1178,7 +1178,6 @@ var podBytes = []byte(`
 apiVersion: v1
 kind: Pod
 metadata:
-  creationTimestamp: "2019-07-08T09:31:18Z"
   labels:
     app: some-app
     plugin1: some-value
@@ -1194,8 +1193,6 @@ metadata:
     kind: ReplicaSet
     name: some-name
     uid: 0a9d2b9e-779e-11e7-b422-42010a8001be
-  selfLink: /api/v1/namespaces/pah
-  uid: 23e8f548-a163-11e9-abe4-42010a80026b
 spec:
   containers:
   - args:
@@ -1329,22 +1326,27 @@ func BenchmarkNoServerSideApply(b *testing.B) {
 }
 
 func getPodSizeWhenEnabled(b *testing.B, pod v1.Pod) int {
+	return len(getPodBytesWhenEnabled(b, pod, "application/vnd.kubernetes.protobuf"))
+}
+
+func getPodBytesWhenEnabled(b *testing.B, pod v1.Pod, format string) []byte {
 	defer featuregatetesting.SetFeatureGateDuringTest(b, utilfeature.DefaultFeatureGate, genericfeatures.ServerSideApply, true)()
 	_, client, closeFn := setup(b)
 	defer closeFn()
 	flag.Lookup("v").Value.Set("0")
 
 	pod.Name = "size-pod"
-	podB, err := client.CoreV1().RESTClient().Post().
+	podB, err := client.CoreV1().RESTClient().Patch(types.ApplyPatchType).
+		Name(pod.Name).
 		Namespace("default").
+		Param("fieldManager", "apply_test").
 		Resource("pods").
-		SetHeader("Content-Type", "application/yaml").
+		SetHeader("Accept", format).
-		SetHeader("Accept", "application/vnd.kubernetes.protobuf").
 		Body(encodePod(pod)).DoRaw()
 	if err != nil {
-		b.Fatalf("Failed to create object: %v", err)
+		b.Fatalf("Failed to create object: %#v", err)
 	}
-	return len(podB)
+	return podB
 }
 
 func BenchmarkNoServerSideApplyButSameSize(b *testing.B) {
@@ -1385,16 +1387,24 @@ func BenchmarkNoServerSideApplyButSameSize(b *testing.B) {
 }
 
 func BenchmarkServerSideApply(b *testing.B) {
+	podBytesWhenEnabled := getPodBytesWhenEnabled(b, decodePod(podBytes), "application/yaml")
+
 	defer featuregatetesting.SetFeatureGateDuringTest(b, utilfeature.DefaultFeatureGate, genericfeatures.ServerSideApply, true)()
 
 	_, client, closeFn := setup(b)
 	defer closeFn()
 	flag.Lookup("v").Value.Set("0")
 
-	benchAll(b, client, decodePod(podBytes))
+	benchAll(b, client, decodePod(podBytesWhenEnabled))
 }
 
 func benchAll(b *testing.B, client kubernetes.Interface, pod v1.Pod) {
+	// Make sure pod is ready to post
+	pod.ObjectMeta.CreationTimestamp = metav1.Time{}
+	pod.ObjectMeta.ResourceVersion = ""
+	pod.ObjectMeta.UID = ""
+	pod.ObjectMeta.SelfLink = ""
+
 	// Create pod for repeated-updates
 	pod.Name = "repeated-pod"
 	_, err := client.CoreV1().RESTClient().Post().