Kubelet should garbage collect dead pods

The sync loop should check for terminated pods that are no longer
running and clear them. The status loop should never write status
if the pod UID changes. Mirror pods should be deleted immediately
rather than gracefully.

pkg/kubelet/status_manager.go

@@ -131,6 +131,29 @@ func (s *statusManager) SetPodStatus(pod *api.Pod, status api.PodStatus) {
 	}
 }
 
+// TerminatePods resets the container status for the provided pods to terminated and triggers
+// a status update. This function may not enqueue all the provided pods, in which case it will
+// return false
+func (s *statusManager) TerminatePods(pods []*api.Pod) bool {
+	sent := true
+	s.podStatusesLock.Lock()
+	defer s.podStatusesLock.Unlock()
+	for _, pod := range pods {
+		for i := range pod.Status.ContainerStatuses {
+			pod.Status.ContainerStatuses[i].State = api.ContainerState{
+				Terminated: &api.ContainerStateTerminated{},
+			}
+		}
+		select {
+		case s.podStatusChannel <- podStatusSyncRequest{pod, pod.Status}:
+		default:
+			sent = false
+			glog.V(4).Infof("Termination notice for %q was dropped because the status channel is full", kubeletUtil.FormatPodName(pod))
+		}
+	}
+	return sent
+}
+
 func (s *statusManager) DeletePodStatus(podFullName string) {
 	s.podStatusesLock.Lock()
 	defer s.podStatusesLock.Unlock()
@@ -167,6 +190,10 @@ func (s *statusManager) syncBatch() error {
 		return nil
 	}
 	if err == nil {
+		if len(pod.UID) > 0 && statusPod.UID != pod.UID {
+			glog.V(3).Infof("Pod %q was deleted and then recreated, skipping status update", kubeletUtil.FormatPodName(pod))
+			return nil
+		}
 		statusPod.Status = status
 		// TODO: handle conflict as a retry, make that easier too.
 		statusPod, err = s.kubeClient.Pods(pod.Namespace).UpdateStatus(statusPod)