From f64c47ef80491e3bc8b78d7a09515d5f65b5dc10 Mon Sep 17 00:00:00 2001
From: Yifan Gu <yifan.gu@coreos.com>
Date: Mon, 4 Apr 2016 18:03:40 -0700
Subject: [PATCH] rkt: Use rkt pod's uuid as the systemd service file's name.

Previously, the service file's name is 'k8s_${POD_UID}.service',
which means we need to `systemctl daemon-reload` if the we replace
the content of the service file (e.g. pod is restarted).

However this makes the journal in the previous pod get disconnected.

This PR solves the issue by using the unique rkt uuid as the service
file's name. After the change, the service file's name will be:
'k8s_${rkt_uuid}.service'.
---
 pkg/kubelet/rkt/rkt.go | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/pkg/kubelet/rkt/rkt.go b/pkg/kubelet/rkt/rkt.go
index 4934acab146..d61f1787950 100644
--- a/pkg/kubelet/rkt/rkt.go
+++ b/pkg/kubelet/rkt/rkt.go
@@ -238,11 +238,11 @@ func (r *Runtime) runCommand(args ...string) ([]string, error) {
 	return strings.Split(strings.TrimSpace(stdout.String()), "\n"), nil
 }
 
-// makePodServiceFileName constructs the unit file name for a pod using its UID.
-func makePodServiceFileName(uid types.UID) string {
+// makePodServiceFileName constructs the unit file name for a pod using its rkt pod uuid.
+func makePodServiceFileName(uuid string) string {
 	// TODO(yifan): Add name for readability? We need to consider the
 	// limit of the length.
-	return fmt.Sprintf("%s_%s.service", kubernetesUnitPrefix, uid)
+	return fmt.Sprintf("%s_%s.service", kubernetesUnitPrefix, uuid)
 }
 
 // setIsolators sets the apps' isolators according to the security context and resource spec.
@@ -846,14 +846,7 @@ func (r *Runtime) preparePod(pod *api.Pod, pullSecrets []api.Secret) (string, *k
 		newUnitOption("Service", "KillMode", "mixed"),
 	}
 
-	// Check if there's old rkt pod corresponding to the same pod, if so, update the restart count.
-	var needReload bool
-	serviceName := makePodServiceFileName(pod.UID)
-	if _, err := os.Stat(serviceFilePath(serviceName)); err == nil {
-		// Service file already exists, that means the pod is being restarted.
-		needReload = true
-	}
-
+	serviceName := makePodServiceFileName(uuid)
 	glog.V(4).Infof("rkt: Creating service file %q for pod %q", serviceName, format.Pod(pod))
 	serviceFile, err := os.Create(serviceFilePath(serviceName))
 	if err != nil {
@@ -863,11 +856,6 @@ func (r *Runtime) preparePod(pod *api.Pod, pullSecrets []api.Secret) (string, *k
 		return "", nil, err
 	}
 	serviceFile.Close()
-	if needReload {
-		if err := r.systemd.Reload(); err != nil {
-			return "", nil, err
-		}
-	}
 
 	return serviceName, apiPodToruntimePod(uuid, pod), nil
 }
@@ -1153,7 +1141,12 @@ func (r *Runtime) KillPod(pod *api.Pod, runningPod kubecontainer.Pod) error {
 		r.waitPreStopHooks(pod, &runningPod)
 	}
 
-	serviceName := makePodServiceFileName(runningPod.ID)
+	containerID, err := parseContainerID(runningPod.Containers[0].ID)
+	if err != nil {
+		glog.Errorf("rkt: Failed to get rkt uuid of the pod %q: %v", runningPod.Name, err)
+		return err
+	}
+	serviceName := makePodServiceFileName(containerID.uuid)
 	r.generateEvents(&runningPod, "Killing", nil)
 	for _, c := range runningPod.Containers {
 		r.containerRefManager.ClearRef(c.ID)
@@ -1169,8 +1162,7 @@ func (r *Runtime) KillPod(pod *api.Pod, runningPod kubecontainer.Pod) error {
 	// Since all service file have 'KillMode=mixed', the processes in
 	// the unit's cgroup will receive a SIGKILL if the normal stop timeouts.
 	reschan := make(chan string)
-	_, err := r.systemd.StopUnit(serviceName, "replace", reschan)
-	if err != nil {
+	if _, err = r.systemd.StopUnit(serviceName, "replace", reschan); err != nil {
 		glog.Errorf("rkt: Failed to stop unit %q: %v", serviceName, err)
 		return err
 	}