Restarting pods in an etcd cluster with PVC is safe.

This is a simple fix that addresses Case C from
https://github.com/coreos/etcd-operator/blob/master/doc/design/persistent_volumes_etcd_data.md

It makes the etcd cluster with PVC able to recover from full k8s cluster
outage. This fixes coreos#1323 inspired by coreos#1323 (comment)

pkg/util/k8sutil/k8sutil.go

@@ -253,6 +253,8 @@ func AddEtcdVolumeToPod(pod *v1.Pod, pvc *v1.PersistentVolumeClaim) {
 		vol.VolumeSource = v1.VolumeSource{
 			PersistentVolumeClaim: &v1.PersistentVolumeClaimVolumeSource{ClaimName: pvc.Name},
 		}
+		// When PVC is used, make the pod auto recover in case of failure
+		pod.Spec.RestartPolicy = v1.RestartPolicyAlways
 	} else {
 		vol.VolumeSource = v1.VolumeSource{EmptyDir: &v1.EmptyDirVolumeSource{}}
 	}