<p>I have been trying to diagnose a problem that just started a few days ago. </p>

<p>Running <code>kubelet</code>, <code>kubeadm</code> version 1.13.1. Cluster has 5 nodes and had been fine for months until late last week. Running this on a RHEL 7.x box with adequate free resources.</p>

<p>Having an odd issue that the cluster resources (api, scheduler, etcd) become unavailable. This eventually corrects itself and the cluster comes back for a while again.</p>

<p>If I do a <code>sudo systemctl restart kubelet</code> everything within the cluster works fine again, until the intermittent oddness occurs.</p>

<p>I am monitoring the <code>journactl</code> logs to see what is going on when this occurs, and the chunk that stands out is:</p>

<pre><code>Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: 2018-12-26 21:28:06.762004 I | etcdserver: skipped leadership transfer for single member cluster
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.763648       1 reflector.go:270] k8s.io/client-go/informers/factory.go:132: watch of *v1beta1.Event ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.762788       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.762910       1 reflector.go:270] storage/cacher.go:/podsecuritypolicy: watch of *policy.PodSecurityPolicy ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.763149       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.763232       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.763439       1 reflector.go:270] storage/cacher.go:/apiregistration.k8s.io/apiservices: watch of *apiregistration.APIService ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.763719       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.763786       1 reflector.go:270] storage/cacher.go:/daemonsets: watch of *apps.DaemonSet ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.763937       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.764016       1 reflector.go:270] storage/cacher.go:/cronjobs: watch of *batch.CronJob ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.764250       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.764324       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.764386       1 reflector.go:270] storage/cacher.go:/services/endpoints: watch of *core.Endpoints ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.764440       1 reflector.go:270] storage/cacher.go:/deployments: watch of *apps.Deployment ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: WARNING: 2018/12/26 21:28:06 grpc: addrConn.transportMonitor exits due to: context canceled
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: 2018-12-26 21:28:06.765201 W | etcdserver/api/v3rpc: failed to receive watch request from gRPC stream ("rpc error: code = Unavailable desc = body closed by handler")
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: 2018-12-26 21:28:06.765384 W | etcdserver/api/v3rpc: failed to receive watch request from gRPC stream ("rpc error: code = Unavailable desc = body closed by handler")
</code></pre>

<p>...</p>

<pre><code>Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.784805       1 reflector.go:270] storage/cacher.go:/controllerrevisions: watch of *apps.ControllerRevision ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.784871       1 reflector.go:270] storage/cacher.go:/pods: watch of *core.Pod ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.786587       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.786700       1 reflector.go:270] storage/cacher.go:/horizontalpodautoscalers: watch of *autoscaling.HorizontalPodAutoscaler ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: E1226 21:28:06.788274       1 watcher.go:208] watch chan error: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain dockerd-current[1609]: W1226 21:28:06.788385       1 reflector.go:270] storage/cacher.go:/crd.projectcalico.org/clusterinformations: watch of *unstructured.Unstructured ended with: Internal error occurred: rpc error: code = Canceled desc = stream terminated by RST_STREAM with error code: CANCEL
Dec 26 15:28:06 thalia0.domain oci-systemd-hook[9353]: systemdhook &lt;debug&gt;: 02cb55687848: Skipping as container command is etcd, not init or systemd
Dec 26 15:28:06 thalia0.domain oci-umount[9355]: umounthook &lt;debug&gt;: 02cb55687848: only runs in prestart stage, ignoring
Dec 26 15:28:07 thalia0.domain dockerd-current[1609]: time="2018-12-26T15:28:07.003175741-06:00" level=warning msg="02cb556878485b24e4705dd0efe1051c02f3e3bbbe7b8a7ab23ea71bd6d82b2f cleanup: failed to unmount secrets: invalid argument"
Dec 26 15:28:07 thalia0.domain kubelet[24604]: E1226 15:28:07.006714   24604 pod_workers.go:190] Error syncing pod 0264932236d6afef396f466fc3bd3181 ("etcd-thalia0.domain_kube-system(0264932236d6afef396f466fc3bd3181)"), skipping: failed to "StartContainer" for "etcd" with CrashLoopBackOff: "Back-off 2m40s restarting failed container=etcd pod=etcd-thalia0.domain_kube-system(0264932236d6afef396f466fc3bd3181)"
Dec 26 15:28:07 thalia0.domain kubelet[24604]: E1226 15:28:07.040361   24604 pod_workers.go:190] Error syncing pod 0264932236d6afef396f466fc3bd3181 ("etcd-thalia0.domain_kube-system(0264932236d6afef396f466fc3bd3181)"), skipping: failed to "StartContainer" for "etcd" with CrashLoopBackOff: "Back-off 2m40s restarting failed container=etcd pod=etcd-thalia0.domain_kube-system(0264932236d6afef396f466fc3bd3181)"
</code></pre>

<p>In order to cut down on the noise in the logs, I cordoned off the other nodes.</p>

<p>As noted, if I do a restart of the <code>kubelet</code> service, everything is fine for a while and then the intermittent behavior occurs. </p>

<p>Any suggestions would be most welcome. I am working with our sys admin and he said it appears that <code>etcd</code> is doing frequent restarts. I think trouble begins when the <code>CrashLoopBackOff</code> starts to happen.</p>

<p>Actually appears to be a RHEL/Docker bug. See <a href="https://bugzilla.redhat.com/show_bug.cgi?id=1655214" rel="nofollow noreferrer">Bug 1655214 - docker exec does not work with registry.access.redhat.com/rhel7:7.3</a></p>

<p>We've applied the fix, and so far things appear to be stable.</p>
