<p>I just installed Kubernetes on a cluster of Ubuntu's using the explanation of <a href="https://www.digitalocean.com/community/tutorials/how-to-create-a-kubernetes-1-11-cluster-using-kubeadm-on-ubuntu-18-04" rel="nofollow noreferrer">digital ocean</a> with Ansible. Everything seems to be fine; but when verifying the cluster, the master node is in a not ready status:</p>

<pre><code># kubectl get nodes
NAME                STATUS     ROLES    AGE   VERSION
jwdkube-master-01   NotReady   master   44m   v1.12.2
jwdkube-worker-01   Ready      &lt;none&gt;   44m   v1.12.2
jwdkube-worker-02   Ready      &lt;none&gt;   44m   v1.12.2
</code></pre>

<p>This is the version:</p>

<pre><code># kubectl version
Client Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.2", GitCommit:"17c77c7898218073f14c8d573582e8d2313dc740", GitTreeState:"clean", BuildDate:"2018-10-24T06:54:59Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.2", GitCommit:"17c77c7898218073f14c8d573582e8d2313dc740", GitTreeState:"clean", BuildDate:"2018-10-24T06:43:59Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
</code></pre>

<p>When I check the master node, the kube-proxy is hanging in a starting mode:</p>

<pre><code># kubectl describe nodes jwdkube-master-01
Name:               jwdkube-master-01
Roles:              master
...
LastTransitionTime                Reason                       Message
----             ------  -----------------                 ------------------                ------                       -------
OutOfDisk        False   Thu, 08 Nov 2018 10:24:45 +0000   Thu, 08 Nov 2018 09:36:10 +0000   KubeletHasSufficientDisk     kubelet has sufficient disk space available
MemoryPressure   False   Thu, 08 Nov 2018 10:24:45 +0000   Thu, 08 Nov 2018 09:36:10 +0000   KubeletHasSufficientMemory   kubelet has sufficient memory available
DiskPressure     False   Thu, 08 Nov 2018 10:24:45 +0000   Thu, 08 Nov 2018 09:36:10 +0000   KubeletHasNoDiskPressure     kubelet has no disk pressure
PIDPressure      False   Thu, 08 Nov 2018 10:24:45 +0000   Thu, 08 Nov 2018 09:36:10 +0000   KubeletHasSufficientPID      kubelet has sufficient PID available
Ready            False   Thu, 08 Nov 2018 10:24:45 +0000   Thu, 08 Nov 2018 09:36:10 +0000   KubeletNotReady              runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
Addresses:
InternalIP:  104.248.207.107
Hostname:    jwdkube-master-01
Capacity:
cpu:                1
ephemeral-storage:  25226960Ki
hugepages-1Gi:      0
hugepages-2Mi:      0
memory:             1008972Ki
pods:               110
Allocatable:
cpu:                1
ephemeral-storage:  23249166298
hugepages-1Gi:      0
hugepages-2Mi:      0
memory:             906572Ki
pods:               110
System Info:
Machine ID:                 771c0f669c0a40a1ba7c28bf1f05a637
System UUID:                771c0f66-9c0a-40a1-ba7c-28bf1f05a637
Boot ID:                    2532ae4d-c08c-45d8-b94c-6e88912ed627
Kernel Version:             4.18.0-10-generic
OS Image:                   Ubuntu 18.10
Operating System:           linux
Architecture:               amd64
Container Runtime Version:  docker://18.6.1
Kubelet Version:            v1.12.2
Kube-Proxy Version:         v1.12.2
PodCIDR:                     10.244.0.0/24
Non-terminated Pods:         (5 in total)
Namespace                  Name                                         CPU Requests  CPU Limits  Memory Requests  Memory Limits
---------                  ----                                         ------------  ----------  ---------------  -------------
kube-system                etcd-jwdkube-master-01                       0 (0%)        0 (0%)      0 (0%)           0 (0%)
kube-system                kube-apiserver-jwdkube-master-01             250m (25%)    0 (0%)      0 (0%)           0 (0%)
kube-system                kube-controller-manager-jwdkube-master-01    200m (20%)    0 (0%)      0 (0%)           0 (0%)
kube-system                kube-proxy-p8cbq                             0 (0%)        0 (0%)      0 (0%)           0 (0%)
kube-system                kube-scheduler-jwdkube-master-01             100m (10%)    0 (0%)      0 (0%)           0 (0%)
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource  Requests    Limits
--------  --------    ------
cpu       550m (55%)  0 (0%)
memory    0 (0%)      0 (0%)
Events:
Type    Reason                   Age                From                           Message
----    ------                   ----               ----                           -------
Normal  NodeHasSufficientDisk    48m (x6 over 48m)  kubelet, jwdkube-master-01     Node jwdkube-master-01 status is now: NodeHasSufficientDisk
Normal  NodeHasSufficientMemory  48m (x6 over 48m)  kubelet, jwdkube-master-01     Node jwdkube-master-01 status is now: NodeHasSufficientMemory
Normal  NodeHasNoDiskPressure    48m (x6 over 48m)  kubelet, jwdkube-master-01     Node jwdkube-master-01 status is now: NodeHasNoDiskPressure
Normal  NodeHasSufficientPID     48m (x5 over 48m)  kubelet, jwdkube-master-01     Node jwdkube-master-01 status is now: NodeHasSufficientPID
Normal  NodeAllocatableEnforced  48m                kubelet, jwdkube-master-01     Updated Node Allocatable limit across pods
Normal  Starting                 48m                kube-proxy, jwdkube-master-01  Starting kube-proxy.
</code></pre>

<p><strong>update</strong></p>

<p>running <code>kubectl get pods -n kube-system</code>:</p>

<pre><code>NAME                                        READY   STATUS    RESTARTS   AGE
coredns-576cbf47c7-8p7k2                    1/1     Running   0          4h47m
coredns-576cbf47c7-s5tlv                    1/1     Running   0          4h47m
etcd-jwdkube-master-01                      1/1     Running   1          140m
kube-apiserver-jwdkube-master-01            1/1     Running   1          140m
kube-controller-manager-jwdkube-master-01   1/1     Running   1          140m
kube-flannel-ds-5bzrx                       1/1     Running   0          4h47m
kube-flannel-ds-bfs9k                       1/1     Running   0          4h47m
kube-proxy-4lrzw                            1/1     Running   1          4h47m
kube-proxy-57x28                            1/1     Running   0          4h47m
kube-proxy-j8bf5                            1/1     Running   0          4h47m
kube-scheduler-jwdkube-master-01            1/1     Running   1          140m
tiller-deploy-6f6fd74b68-5xt54              1/1     Running   0          112m
</code></pre>

<p>It seems to be a problem of Flannel <code>v0.9.1</code> compatibility with Kubernetes cluster <code>v1.12.2</code>. Once you replace URL in master configuration playbook it should help:</p>

<p><code>kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/
kube-flannel.yml</code></p>

<p>To enforce this solution on the current cluster:</p>

<hr>

<ol>
<li><p>On the master node delete relevant objects for Flannel v0.9.1:</p>

<p><code>kubectl delete clusterrole flannel -n kube-system</code></p>

<p><code>kubectl delete clusterrolebinding flannel-n kube-system</code></p>

<p><code>kubectl delete clusterrolebinding flannel -n kube-system</code></p>

<p><code>kubectl delete serviceaccount flannel -n kube-system</code></p>

<p><code>kubectl delete configmap kube-flannel-cfg -n kube-system</code></p>

<p><code>kubectl delete daemonset.extensions kube-flannel-ds -n kube-system</code></p>

<p>Proceed also with Flannel Pods deletion:</p>

<p><code>kubectl delete pod kube-flannel-ds-5bzrx -n kube-system</code></p>

<p><code>kubectl delete pod kube-flannel-ds-bfs9k -n kube-system</code></p>

<p>And check whether no more objects related to Flannel exist:</p>

<p><code>kubectl get all --all-namespaces</code></p></li>
</ol>

<hr>

<ol start="2">
<li>Install the latest Flannel version to your cluster:</li>
</ol>

<p><code>kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml</code></p>

<p>For me it works, however if you discover any further problems write a comment below this answer.</p>
