add pod garbage collection

pkg/controller/gc/doc.go

@@ -0,0 +1,24 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 gc contains a very simple pod "garbage collector" implementation,
+// GCController, that runs in the controller manager. If the number of pods
+// in terminated phases (right now either Failed or Succeeded) surpasses a
+// configurable threshold, the controller will delete pods in terminated state
+// until the system reaches the allowed threshold again. The GCController
+// prioritizes pods to delete by sorting by creation timestamp and deleting the
+// oldest objects first. The GCController will not delete non-terminated pods.
+package gc