Remove all metadata fields but labels from targets of kf federate

CHANGELOG.md

@@ -1,4 +1,10 @@
 # Unreleased
+-  [#1086](https://github.com/kubernetes-sigs/kubefed/pull/1086)
+   `kubefedctl federate` now removes all metadata fields except labels
+   from the template of federated resources created from a
+   non-federated resource. Previously `metadata.annotations` and
+   `metadata.finalizers` were not removed which could result in
+   propagation errors.
 -  [#1079](https://github.com/kubernetes-sigs/kubefed/issues/1079) The
    spec field is now required in generated federated types. For types
    generated previously, a check has been added so that a missing spec

pkg/kubefedctl/federate/federate.go

@@ -361,8 +361,10 @@ func FederatedResourceFromTargetResource(typeConfig typeconfig.Interface, resour
 	fedAPIResource := typeConfig.GetFederatedType()
 	targetResource := resource.DeepCopy()
 
+	targetKind := typeConfig.GetTargetType().Kind
+
 	// Special handling is needed for some controller set fields.
-	switch typeConfig.GetTargetType().Kind {
+	switch targetKind {
 	case ctlutil.NamespaceKind:
 		{
 			unstructured.RemoveNestedField(targetResource.Object, "spec", "finalizers")
@@ -397,9 +399,22 @@ func FederatedResourceFromTargetResource(typeConfig typeconfig.Interface, resour
 	resourceNamespace := getNamespace(typeConfig, qualifiedName)
 	fedResource := &unstructured.Unstructured{}
 	SetBasicMetaFields(fedResource, fedAPIResource, qualifiedName.Name, resourceNamespace, "")
-	RemoveUnwantedFields(targetResource)
 
-	err := unstructured.SetNestedField(fedResource.Object, targetResource.Object, ctlutil.SpecField, ctlutil.TemplateField)
+	// Warn if annotations are present in case the intention is to
+	// define annotations in the template of the federated resource.
+	annotations, _, err := unstructured.NestedMap(targetResource.Object, "metadata", "annotations")
+	if err != nil {
+		return nil, errors.Wrap(err, "Failed to retrieve metadata.annotations")
+	}
+	if len(annotations) > 0 {
+		klog.Warningf("Annotations defined for %s %q will not appear in the template of the federated resource: %v", targetKind, qualifiedName, annotations)
+	}
+
+	if err := RemoveUnwantedFields(targetResource); err != nil {
+		return nil, err
+	}
+
+	err = unstructured.SetNestedField(fedResource.Object, targetResource.Object, ctlutil.SpecField, ctlutil.TemplateField)
 	if err != nil {
 		return nil, err
 	}

pkg/kubefedctl/federate/util.go

@@ -38,19 +38,27 @@ import (
 	"sigs.k8s.io/kubefed/pkg/kubefedctl/util"
 )
 
-var systemMetadataFields = []string{"selfLink", "uid", "resourceVersion", "generation", "creationTimestamp", "deletionTimestamp", "deletionGracePeriodSeconds"}
-
-func RemoveUnwantedFields(resource *unstructured.Unstructured) {
-	for _, field := range systemMetadataFields {
-		unstructured.RemoveNestedField(resource.Object, "metadata", field)
-		// For resources with pod template subresource (jobs, deployments, replicasets)
-		unstructured.RemoveNestedField(resource.Object, "spec", "template", "metadata", field)
-	}
-	unstructured.RemoveNestedField(resource.Object, "metadata", "name")
-	unstructured.RemoveNestedField(resource.Object, "metadata", "namespace")
+func RemoveUnwantedFields(resource *unstructured.Unstructured) error {
 	unstructured.RemoveNestedField(resource.Object, "apiVersion")
 	unstructured.RemoveNestedField(resource.Object, "kind")
 	unstructured.RemoveNestedField(resource.Object, "status")
+
+	// All metadata fields save labels should be cleared. Other
+	// metadata fields will be set by the system on creation or
+	// subsequently by controllers.
+	labels, _, err := unstructured.NestedMap(resource.Object, "metadata", "labels")
+	if err != nil {
+		return errors.Wrap(err, "Failed to retrieve metadata.labels")
+	}
+	unstructured.RemoveNestedField(resource.Object, "metadata")
+	if len(labels) > 0 {
+		err := unstructured.SetNestedMap(resource.Object, labels, "metadata", "labels")
+		if err != nil {
+			return errors.Wrap(err, "Failed to set metadata.labels")
+		}
+	}
+
+	return nil
 }
 
 func SetBasicMetaFields(resource *unstructured.Unstructured, apiResource metav1.APIResource, name, namespace, generateName string) {

test/e2e/federate.go

@@ -264,8 +264,12 @@ func validateTemplateEquality(tl common.TestLogger, fedResource, targetResource
 
 	expectedResource := &unstructured.Unstructured{}
 	expectedResource.Object = templateMap.(map[string]interface{})
-	federate.RemoveUnwantedFields(expectedResource)
-	federate.RemoveUnwantedFields(targetResource)
+	if err := federate.RemoveUnwantedFields(expectedResource); err != nil {
+		tl.Fatalf("Failed to remove unwanted fields from expected resource: %v", err)
+	}
+	if err := federate.RemoveUnwantedFields(targetResource); err != nil {
+		tl.Fatalf("Failed to remove unwanted fields from target resource: %v", err)
+	}
 	if kind == util.NamespaceKind {
 		unstructured.RemoveNestedField(targetResource.Object, "spec", "finalizers")
 	}