Initialize UID earlier in the Create process

Before:
  Create()
      BeginCreate()
      BeforeCreate()
          init UID <---------------------
          strategy code

After:
  Create()
      init UID <-------------------------
      BeginCreate()
      BeforeCreate()
          strategy code

This also wipes UID early (suggested by David) and asserts it is set in
BeforeCreate().

Kubernetes-commit: 5615de51f9e768dd01d7fe49a48e8db756bd8ac8

pkg/endpoints/handlers/create.go

@@ -163,8 +163,10 @@ func createHandler(r rest.NamedCreater, scope *RequestScope, admit admission.Int
 
 		userInfo, _ := request.UserFrom(ctx)
 
-		// if this object supports namespace info
 		if objectMeta, err := meta.Accessor(obj); err == nil {
+			// Wipe fields which cannot take user-provided values
+			rest.WipeObjectMetaSystemFields(objectMeta)
+
 			// ensure namespace on the object is correct, or error if a conflicting namespace was set in the object
 			if err := rest.EnsureObjectNamespaceMatchesRequestNamespace(rest.ExpectedNamespaceForResource(namespace, scope.Resource), objectMeta); err != nil {
 				scope.err(err, w, req)

pkg/registry/generic/registry/store.go

@@ -382,6 +382,13 @@ func finishNothing(context.Context, bool) {}
 func (e *Store) Create(ctx context.Context, obj runtime.Object, createValidation rest.ValidateObjectFunc, options *metav1.CreateOptions) (runtime.Object, error) {
 	var finishCreate FinishFunc = finishNothing
 
+	// Init metadata as early as possible.
+	if objectMeta, err := meta.Accessor(obj); err != nil {
+		return nil, err
+	} else {
+		rest.FillObjectMetaSystemFields(objectMeta)
+	}
+
 	if e.BeginCreate != nil {
 		fn, err := e.BeginCreate(ctx, obj, options)
 		if err != nil {
@@ -558,6 +565,13 @@ func (e *Store) Update(ctx context.Context, name string, objInfo rest.UpdatedObj
 		doUnconditionalUpdate := newResourceVersion == 0 && e.UpdateStrategy.AllowUnconditionalUpdate()
 
 		if existingResourceVersion == 0 {
+			// Init metadata as early as possible.
+			if objectMeta, err := meta.Accessor(obj); err != nil {
+				return nil, nil, err
+			} else {
+				rest.FillObjectMetaSystemFields(objectMeta)
+			}
+
 			var finishCreate FinishFunc = finishNothing
 
 			if e.BeginCreate != nil {

pkg/registry/rest/create.go

@@ -100,6 +100,11 @@ func BeforeCreate(strategy RESTCreateStrategy, ctx context.Context, obj runtime.
 		return kerr
 	}
 
+	// ensure that system-critical metadata has been populated
+	if !metav1.HasObjectMetaSystemFieldValues(objectMeta) {
+		return errors.NewInternalError(fmt.Errorf("system metadata was not initialized"))
+	}
+
 	// ensure namespace on the object is correct, or error if a conflicting namespace was set in the object
 	requestNamespace, ok := genericapirequest.NamespaceFrom(ctx)
 	if !ok {
@@ -109,10 +114,7 @@ func BeforeCreate(strategy RESTCreateStrategy, ctx context.Context, obj runtime.
 		return err
 	}
 
-	objectMeta.SetDeletionTimestamp(nil)
-	objectMeta.SetDeletionGracePeriodSeconds(nil)
 	strategy.PrepareForCreate(ctx, obj)
-	FillObjectMetaSystemFields(objectMeta)
 
 	if len(objectMeta.GetGenerateName()) > 0 && len(objectMeta.GetName()) == 0 {
 		objectMeta.SetName(strategy.GenerateName(objectMeta.GetGenerateName()))

pkg/registry/rest/meta.go

@@ -23,11 +23,19 @@ import (
 	"k8s.io/apimachinery/pkg/util/uuid"
 )
 
+// WipeObjectMetaSystemFields erases fields that are managed by the system on ObjectMeta.
+func WipeObjectMetaSystemFields(meta metav1.Object) {
+	meta.SetCreationTimestamp(metav1.Time{})
+	meta.SetUID("")
+	meta.SetDeletionTimestamp(nil)
+	meta.SetDeletionGracePeriodSeconds(nil)
+	meta.SetSelfLink("")
+}
+
 // FillObjectMetaSystemFields populates fields that are managed by the system on ObjectMeta.
 func FillObjectMetaSystemFields(meta metav1.Object) {
 	meta.SetCreationTimestamp(metav1.Now())
 	meta.SetUID(uuid.NewUUID())
-	meta.SetSelfLink("")
 }
 
 // EnsureObjectNamespaceMatchesRequestNamespace returns an error if obj.Namespace and requestNamespace

pkg/registry/rest/meta_test.go

@@ -23,14 +23,33 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
+// TestWipeObjectMetaSystemFields validates that system populated fields are set on an object
+func TestWipeObjectMetaSystemFields(t *testing.T) {
+	resource := metav1.ObjectMeta{}
+	WipeObjectMetaSystemFields(&resource)
+	if !resource.CreationTimestamp.Time.IsZero() {
+		t.Errorf("resource.CreationTimestamp is set")
+	}
+	if len(resource.UID) != 0 {
+		t.Errorf("resource.UID is set")
+	}
+	if resource.DeletionTimestamp != nil {
+		t.Errorf("resource.DeletionTimestamp is set")
+	}
+	if resource.DeletionGracePeriodSeconds != nil {
+		t.Errorf("resource.DeletionGracePeriodSeconds is set")
+	}
+	if len(resource.SelfLink) != 0 {
+		t.Errorf("resource.SelfLink is set")
+	}
+}
+
 // TestFillObjectMetaSystemFields validates that system populated fields are set on an object
 func TestFillObjectMetaSystemFields(t *testing.T) {
 	resource := metav1.ObjectMeta{}
 	FillObjectMetaSystemFields(&resource)
 	if resource.CreationTimestamp.Time.IsZero() {
 		t.Errorf("resource.CreationTimestamp is zero")
-	} else if len(resource.UID) == 0 {
-		t.Errorf("resource.UID missing")
 	}
 	if len(resource.UID) == 0 {
 		t.Errorf("resource.UID missing")