From cb57dc4cb58cf3f551645475f4b6896fbe5b14b5 Mon Sep 17 00:00:00 2001
From: Yu-Ju Hong <yjhong@google.com>
Date: Fri, 23 Sep 2016 14:04:17 -0700
Subject: [PATCH] kuberuntime: include container hash in backoff keys

We should reset the backoff if the content of the container has been updated.
---
 pkg/kubelet/kuberuntime/helpers.go            |  9 ++++
 pkg/kubelet/kuberuntime/helpers_test.go       | 47 +++++++++++++++++++
 .../kuberuntime/kuberuntime_manager.go        | 10 ++--
 3 files changed, 61 insertions(+), 5 deletions(-)
 create mode 100644 pkg/kubelet/kuberuntime/helpers_test.go

diff --git a/pkg/kubelet/kuberuntime/helpers.go b/pkg/kubelet/kuberuntime/helpers.go
index 67928e3783..d5684f2e48 100644
--- a/pkg/kubelet/kuberuntime/helpers.go
+++ b/pkg/kubelet/kuberuntime/helpers.go
@@ -18,6 +18,7 @@ package kuberuntime
 
 import (
 	"fmt"
+	"strconv"
 
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/api"
@@ -160,3 +161,11 @@ func milliCPUToQuota(milliCPU int64) (quota int64, period int64) {
 
 	return
 }
+
+// getStableKey generates a key (string) to uniquely identify a
+// (pod, container) tuple. The key should include the content of the
+// container, so that any change to the container generates a new key.
+func getStableKey(pod *api.Pod, container *api.Container) string {
+	hash := strconv.FormatUint(kubecontainer.HashContainer(container), 16)
+	return fmt.Sprintf("%s_%s_%s_%s_%s", pod.Name, pod.Namespace, string(pod.UID), container.Name, hash)
+}
diff --git a/pkg/kubelet/kuberuntime/helpers_test.go b/pkg/kubelet/kuberuntime/helpers_test.go
new file mode 100644
index 0000000000..c1b2782bbd
--- /dev/null
+++ b/pkg/kubelet/kuberuntime/helpers_test.go
@@ -0,0 +1,47 @@
+/*
+Copyright 2016 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 kuberuntime
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/kubernetes/pkg/api"
+)
+
+func TestStableKey(t *testing.T) {
+	container := &api.Container{
+		Name:  "test_container",
+		Image: "foo/image:v1",
+	}
+	pod := &api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			Name:      "test_pod",
+			Namespace: "test_pod_namespace",
+			UID:       "test_pod_uid",
+		},
+		Spec: api.PodSpec{
+			Containers: []api.Container{*container},
+		},
+	}
+	oldKey := getStableKey(pod, container)
+
+	// Updating the container image should change the key.
+	container.Image = "foo/image:v2"
+	newKey := getStableKey(pod, container)
+	assert.NotEqual(t, oldKey, newKey)
+}
diff --git a/pkg/kubelet/kuberuntime/kuberuntime_manager.go b/pkg/kubelet/kuberuntime/kuberuntime_manager.go
index b5c26f6f00..541e10b763 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_manager.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_manager.go
@@ -627,18 +627,18 @@ func (m *kubeGenericRuntimeManager) doBackOff(pod *api.Pod, container *api.Conta
 	glog.Infof("checking backoff for container %q in pod %q", container.Name, format.Pod(pod))
 	// Use the finished time of the latest exited container as the start point to calculate whether to do back-off.
 	ts := cStatus.FinishedAt
-	// backOff requires a unique id to identify the container
-	stableName := fmt.Sprintf("%s_%s_%s_%s", pod.Name, pod.Namespace, string(pod.UID), container.Name)
-	if backOff.IsInBackOffSince(stableName, ts) {
+	// backOff requires a unique key to identify the container.
+	key := getStableKey(pod, container)
+	if backOff.IsInBackOffSince(key, ts) {
 		if ref, err := kubecontainer.GenerateContainerRef(pod, container); err == nil {
 			m.recorder.Eventf(ref, api.EventTypeWarning, events.BackOffStartContainer, "Back-off restarting failed container")
 		}
-		err := fmt.Errorf("Back-off %s restarting failed container=%s pod=%s", backOff.Get(stableName), container.Name, format.Pod(pod))
+		err := fmt.Errorf("Back-off %s restarting failed container=%s pod=%s", backOff.Get(key), container.Name, format.Pod(pod))
 		glog.Infof("%s", err.Error())
 		return true, err.Error(), kubecontainer.ErrCrashLoopBackOff
 	}
 
-	backOff.Next(stableName, ts)
+	backOff.Next(key, ts)
 	return false, "", nil
 }