construction of GC should not fail for restmapper error caused by tpr

pkg/controller/garbagecollector/errors.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package garbagecollector
+
+import (
+	"fmt"
+)
+
+const nonCoreMessage = `If %s is a non-core resource (e.g. thirdparty resource, custom resource from aggregated apiserver), please note that the garbage collector doesn't support non-core resources yet. Once they are supported, object with ownerReferences referring non-existing non-core objects will be deleted by the garbage collector.`
+
+type restMappingError struct {
+	kind    string
+	version string
+}
+
+func (r *restMappingError) Error() string {
+	versionKind := fmt.Sprintf("%s/%s", r.version, r.kind)
+	return fmt.Sprintf("unable to get REST mapping for %s.", versionKind)
+}
+
+// Message prints more details
+func (r *restMappingError) Message() string {
+	versionKind := fmt.Sprintf("%s/%s", r.version, r.kind)
+	errMsg := fmt.Sprintf("unable to get REST mapping for %s. ", versionKind)
+	errMsg += fmt.Sprintf(nonCoreMessage, versionKind)
+	errMsg += fmt.Sprintf(" If %s is an invalid resource, then you should manually remove ownerReferences that refer %s objects.", versionKind, versionKind)
+	return errMsg
+}
+
+func newRESTMappingError(kind, version string) *restMappingError {
+	return &restMappingError{kind: kind, version: version}
+}