Move TerminationMessagePath into docker label.

pkg/kubelet/dockertools/labels.go

@@ -32,10 +32,12 @@ const (
 	kubernetesPodNamespaceLabel = "io.kubernetes.pod.namespace"
 	kubernetesPodUID            = "io.kubernetes.pod.uid"
 
+	kubernetesContainerRestartCountLabel      = "io.kubernetes.container.restartCount"
+	kubernetesContainerTerminationMessagePath = "io.kubernetes.container.terminationMessagePath"
+
 	kubernetesPodLabel                    = "io.kubernetes.pod.data"
 	kubernetesTerminationGracePeriodLabel = "io.kubernetes.pod.terminationGracePeriod"
 	kubernetesContainerLabel              = "io.kubernetes.container.name"
-	kubernetesContainerRestartCountLabel  = "io.kubernetes.container.restartCount"
 )
 
 func newLabels(container *api.Container, pod *api.Pod, restartCount int) map[string]string {
@@ -46,6 +48,7 @@ func newLabels(container *api.Container, pod *api.Pod, restartCount int) map[str
 	labels[kubernetesPodUID] = string(pod.UID)
 
 	labels[kubernetesContainerRestartCountLabel] = strconv.Itoa(restartCount)
+	labels[kubernetesContainerTerminationMessagePath] = container.TerminationMessagePath
 
 	return labels
 }
@@ -65,3 +68,14 @@ func getRestartCountFromLabel(labels map[string]string) (restartCount int, err e
 	}
 	return restartCount, err
 }
+
+func getTerminationMessagePathFromLabel(labels map[string]string) string {
+	if terminationMessagePath, found := labels[kubernetesContainerTerminationMessagePath]; found {
+		return terminationMessagePath
+	} else {
+		// Do not report error, because there should be many old containers without this label now.
+		// Return empty string "" for these containers, the caller will get terminationMessagePath by other ways.
+		glog.V(3).Infof("Container doesn't have label %s, it may be an old or invalid container", kubernetesContainerTerminationMessagePath)
+		return ""
+	}
+}

pkg/kubelet/dockertools/manager.go

@@ -338,6 +338,7 @@ func (dm *DockerManager) determineContainerIP(podNamespace, podName string, cont
 	return result
 }
 
+// TODO (random-liu) Remove parameter tPath when old containers are deprecated.
 func (dm *DockerManager) inspectContainer(dockerID, containerName, tPath string, pod *api.Pod) *containerStatusResult {
 	result := containerStatusResult{api.ContainerStatus{}, "", nil}
 
@@ -408,8 +409,14 @@ func (dm *DockerManager) inspectContainer(dockerID, containerName, tPath string,
 			FinishedAt:  finishedAt,
 			ContainerID: DockerPrefix + dockerID,
 		}
-		if tPath != "" {
-			path, found := inspectResult.Volumes[tPath]
+		terminationMessagePath := getTerminationMessagePathFromLabel(inspectResult.Config.Labels)
+		if terminationMessagePath == "" {
+			// Because old containers have no terminationMessagePath Label, we stil have to rely on the information from apiserver here.
+			// TODO (random-liu) Remove this later when old containers with no labels are deprecated.
+			terminationMessagePath = tPath
+		}
+		if terminationMessagePath != "" {
+			path, found := inspectResult.Volumes[terminationMessagePath]
 			if found {
 				data, err := ioutil.ReadFile(path)
 				if err != nil {

pkg/kubelet/dockertools/manager_test.go

@@ -1600,6 +1600,44 @@ func TestGetRestartCount(t *testing.T) {
 	pod.Status = verifyRestartCount(&pod, 4)
 }
 
+func TestGetTerminationMessagePath(t *testing.T) {
+	dm, fakeDocker := newTestDockerManager()
+	containers := []api.Container{
+		{
+			Name: "bar",
+			TerminationMessagePath: "/dev/somepath",
+		},
+	}
+	pod := &api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			UID:       "12345678",
+			Name:      "foo",
+			Namespace: "new",
+		},
+		Spec: api.PodSpec{
+			Containers: containers,
+		},
+	}
+
+	fakeDocker.ContainerMap = map[string]*docker.Container{}
+
+	runSyncPod(t, dm, fakeDocker, pod, nil)
+
+	containerList := fakeDocker.ContainerList
+	if len(containerList) != 2 {
+		// One for infra container, one for container "bar"
+		t.Fatalf("unexpected container list length %d", len(containerList))
+	}
+	inspectResult, err := dm.client.InspectContainer(containerList[0].ID)
+	if err != nil {
+		t.Fatalf("unexpected inspect error %v", err)
+	}
+	terminationMessagePath := getTerminationMessagePathFromLabel(inspectResult.Config.Labels)
+	if terminationMessagePath != containers[0].TerminationMessagePath {
+		t.Errorf("expected termination message path %s, got %s", containers[0].TerminationMessagePath, terminationMessagePath)
+	}
+}
+
 func TestSyncPodWithPodInfraCreatesContainerCallsHandler(t *testing.T) {
 	fakeHTTPClient := &fakeHTTP{}
 	dm, fakeDocker := newTestDockerManagerWithHTTPClient(fakeHTTPClient)