<p>I've been working with a 6 node cluster for the last few weeks without issue. Earlier today we ran into an open file issue (<a href="https://github.com/kubernetes/kubernetes/pull/12443/files" rel="nofollow">https://github.com/kubernetes/kubernetes/pull/12443/files</a>) and I patched and restarted kube-proxy. </p>

<p>Since then, all rc deployed pods to ALL BUT node-01 get stuck in pending state and there log messages stating the cause.</p>

<p>Looking at the docker daemon on the nodes, the containers in the pod are actually running and a delete of the rc removes them. It appears to be some sort of callback issue between the state according to kubelet and the kube-apiserver.</p>

<p>Cluster is running v1.0.3</p>

<p>Here's an example of the state</p>

<pre><code>docker run --rm -it lachie83/kubectl:prod get pods --namespace=kube-system -o wide
NAME                READY     STATUS    RESTARTS   AGE       NODE
kube-dns-v8-i0yac   0/4       Pending   0          4s        10.1.1.35
kube-dns-v8-jti2e   0/4       Pending   0          4s        10.1.1.34
</code></pre>

<p>get events</p>

<pre><code>Wed, 16 Sep 2015 06:25:42 +0000   Wed, 16 Sep 2015 06:25:42 +0000   1         kube-dns-v8                       ReplicationController                                                successfulCreate   {replication-controller }   Created pod: kube-dns-v8-i0yac
Wed, 16 Sep 2015 06:25:42 +0000   Wed, 16 Sep 2015 06:25:42 +0000   1         kube-dns-v8-i0yac                 Pod                                                                  scheduled          {scheduler }                Successfully assigned kube-dns-v8-i0yac to 10.1.1.35
Wed, 16 Sep 2015 06:25:42 +0000   Wed, 16 Sep 2015 06:25:42 +0000   1         kube-dns-v8-jti2e                 Pod                                                                  scheduled          {scheduler }                Successfully assigned kube-dns-v8-jti2e to 10.1.1.34
Wed, 16 Sep 2015 06:25:42 +0000   Wed, 16 Sep 2015 06:25:42 +0000   1         kube-dns-v8                       ReplicationController                                                successfulCreate   {replication-controller }   Created pod: kube-dns-v8-jti2e
</code></pre>

<p>scheduler log</p>

<pre><code>I0916 06:25:42.897814   10076 event.go:203] Event(api.ObjectReference{Kind:"Pod", Namespace:"kube-system", Name:"kube-dns-v8-jti2e", UID:"c1cafebe-5c3b-11e5-b3c4-020443b6797d", APIVersion:"v1", ResourceVersion:"670117", FieldPath:""}): reason: 'scheduled' Successfully assigned kube-dns-v8-jti2e to 10.1.1.34
I0916 06:25:42.904195   10076 event.go:203] Event(api.ObjectReference{Kind:"Pod", Namespace:"kube-system", Name:"kube-dns-v8-i0yac", UID:"c1cafc69-5c3b-11e5-b3c4-020443b6797d", APIVersion:"v1", ResourceVersion:"670118", FieldPath:""}): reason: 'scheduled' Successfully assigned kube-dns-v8-i0yac to 10.1.1.35
</code></pre>

<p>tailing kubelet log file during pod create</p>

<pre><code>tail -f kubelet.kube-node-03.root.log.INFO.20150916-060744.10668
I0916 06:25:04.448916   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:25:24.449253   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:25:44.449522   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:26:04.449774   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:26:24.450400   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:26:44.450995   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:27:04.451501   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:27:24.451910   10668 config.go:253] Setting pods for source file : {[] 0 file}
I0916 06:27:44.452511   10668 config.go:253] Setting pods for source file : {[] 0 file}
</code></pre>

<p>kubelet process</p>

<pre><code>root@kube-node-03:/var/log/kubernetes# ps -ef | grep kubelet
root     10668     1  1 06:07 ?        00:00:13 /opt/bin/kubelet --address=10.1.1.34 --port=10250 --hostname_override=10.1.1.34 --api_servers=https://kube-master-01.sj.lithium.com:6443 --logtostderr=false --log_dir=/var/log/kubernetes --cluster_dns=10.1.2.53 --config=/etc/kubelet/conf --cluster_domain=prod-kube-sjc1-1.internal --v=4 --tls-cert-file=/etc/kubelet/certs/kubelet.pem --tls-private-key-file=/etc/kubelet/certs/kubelet-key.pem
</code></pre>

<p>node list</p>

<pre><code>docker run --rm -it lachie83/kubectl:prod get nodes
NAME            LABELS                                             STATUS
10.1.1.30   kubernetes.io/hostname=10.1.1.30,name=node-1   Ready
10.1.1.32   kubernetes.io/hostname=10.1.1.32,name=node-2   Ready
10.1.1.34   kubernetes.io/hostname=10.1.1.34,name=node-3   Ready
10.1.1.35   kubernetes.io/hostname=10.1.1.35,name=node-4   Ready
10.1.1.42   kubernetes.io/hostname=10.1.1.42,name=node-5   Ready
10.1.1.43   kubernetes.io/hostname=10.1.1.43,name=node-6   Ready
</code></pre>

<p>The issue turned out to be an MTU issue between the node and the master. Once that was fixed the problem was resolved.</p>
