Merge pull request #1056 from xunpan/enable

check if federated type is referred by an existing FTC

pkg/kubefedctl/enable/enable.go

@@ -282,6 +282,25 @@ func CreateResources(cmdOut io.Writer, config *rest.Config, resources *typeResou
 	} else if err != nil {
 		return errors.Wrapf(err, "Error getting CRD %q", resources.CRD.Name)
 	} else {
+		ftcs := &fedv1b1.FederatedTypeConfigList{}
+		err := client.List(context.TODO(), ftcs, namespace)
+		if err != nil {
+			return errors.Wrap(err, "Error getting FederatedTypeConfig list")
+		}
+
+		for _, ftc := range ftcs.Items {
+			if concreteTypeConfig.Name == ftc.Name {
+				continue
+			}
+
+			fedType := ftc.Spec.FederatedType
+			name := typeconfig.GroupQualifiedName(metav1.APIResource{Name: fedType.PluralName, Group: fedType.Group})
+			if name == existingCRD.Name {
+				return errors.Errorf("Failed to enable federation of %q due to the FederatedTypeConfig for %q already referencing a federated type CRD named %q. If these target types are distinct despite sharing the same kind, specifying a non-default --federation-group should allow %q to be enabled.",
+					concreteTypeConfig.Name, ftc.Name, name, concreteTypeConfig.Name)
+			}
+		}
+
 		existingCRD.Spec = resources.CRD.Spec
 		_, err = crdClient.CustomResourceDefinitions().Update(existingCRD)
 		if err != nil {