Improve mirror pod creation/deletion

- Ignore the "not found" error on deletion.
 - Recognize the "already exists" error on creation and check if the existing
   pod meets requirement. If so, don't report an error.
 - Immediately create a mirror pod after a successful deletion, if needed.

pkg/kubelet/kubelet.go

@@ -1618,24 +1618,22 @@ func (kl *Kubelet) syncPod(pod *api.Pod, mirrorPod *api.Pod, runningPod kubecont
 	// Create Mirror Pod for Static Pod if it doesn't already exist
 	if kubepod.IsStaticPod(pod) {
 		podFullName := kubecontainer.GetPodFullName(pod)
+		deleted := false
 		if mirrorPod != nil && !kl.podManager.IsMirrorPodOf(mirrorPod, pod) {
 			// The mirror pod is semantically different from the static pod. Remove
 			// it. The mirror pod will get recreated later.
 			glog.Errorf("Deleting mirror pod %q because it is outdated", format.Pod(mirrorPod))
 			if err := kl.podManager.DeleteMirrorPod(podFullName); err != nil {
 				glog.Errorf("Failed deleting mirror pod %q: %v", format.Pod(mirrorPod), err)
+			} else {
+				deleted = true
 			}
 		}
-		if mirrorPod == nil {
+		if mirrorPod == nil || deleted {
 			glog.V(3).Infof("Creating a mirror pod for static pod %q", format.Pod(pod))
 			if err := kl.podManager.CreateMirrorPod(pod); err != nil {
 				glog.Errorf("Failed creating a mirror pod for %q: %v", format.Pod(pod), err)
 			}
-
-			_, ok := kl.podManager.GetMirrorPodByPod(pod)
-			if !ok {
-				glog.Errorf("Mirror pod not available")
-			}
 		}
 	}
 

pkg/kubelet/kubelet_test.go

@@ -3399,8 +3399,8 @@ func TestDeleteOutdatedMirrorPod(t *testing.T) {
 	}
 	name := kubecontainer.GetPodFullName(pod)
 	creates, deletes := manager.GetCounts(name)
-	if creates != 0 || deletes != 1 {
-		t.Errorf("expected 0 creation and 1 deletion of %q, got %d, %d", name, creates, deletes)
+	if creates != 1 || deletes != 1 {
+		t.Errorf("expected 1 creation and 1 deletion of %q, got %d, %d", name, creates, deletes)
 	}
 }
 

pkg/kubelet/pod/mirror_client.go

@@ -19,6 +19,7 @@ package pod
 import (
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/errors"
 	client "k8s.io/kubernetes/pkg/client/unversioned"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
@@ -52,9 +53,15 @@ func (mc *basicMirrorClient) CreateMirrorPod(pod *api.Pod) error {
 	for k, v := range pod.Annotations {
 		copyPod.Annotations[k] = v
 	}
-	copyPod.Annotations[kubetypes.ConfigMirrorAnnotationKey] = getPodHash(pod)
-
-	_, err := mc.apiserverClient.Pods(copyPod.Namespace).Create(&copyPod)
+	hash := getPodHash(pod)
+	copyPod.Annotations[kubetypes.ConfigMirrorAnnotationKey] = hash
+	apiPod, err := mc.apiserverClient.Pods(copyPod.Namespace).Create(&copyPod)
+	if err != nil && errors.IsAlreadyExists(err) {
+		// Check if the existing pod is the same as the pod we want to create.
+		if h, ok := apiPod.Annotations[kubetypes.ConfigMirrorAnnotationKey]; ok && h == hash {
+			return nil
+		}
+	}
 	return err
 }
 
@@ -69,7 +76,7 @@ func (mc *basicMirrorClient) DeleteMirrorPod(podFullName string) error {
 		return err
 	}
 	glog.V(4).Infof("Deleting a mirror pod %q", podFullName)
-	if err := mc.apiserverClient.Pods(namespace).Delete(name, api.NewDeleteOptions(0)); err != nil {
+	if err := mc.apiserverClient.Pods(namespace).Delete(name, api.NewDeleteOptions(0)); err != nil && !errors.IsNotFound(err) {
 		glog.Errorf("Failed deleting a mirror pod %q: %v", podFullName, err)
 	}
 	return nil