Only update managedFields on update if it already exists

Kubernetes-commit: 9a12e37a6dc28fd1d209eb84c210eb0723e6e38f

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 {

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",

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)
 }