<p>I'm Doing some homework ( linuxacademy tutorial ) with kubernetes ( 1 masters and 2 nodes )
Trying add my node1 using command kubeadm join on the node.</p>

<p>The command is pending without any error or result.
I have tried on the node2 and I have the exact same result.
I must kill the process with ctrl+c to exit</p>

<pre><code>[root@K8SNode2 rbo]# kubeadm join 192.168.1.43:6443 --token 9jh998.01jsgbnvsg9373ix \
&gt;     --discovery-token-ca-cert-hash sha256:60df8024a4ee96018136424af429c5c16ffd15805                                                                                                                53128c83d4fc4861829197f
[preflight] Running pre-flight checks
        [WARNING SystemVerification]: this Docker version is not on the list of valid                                                                                                                ated versions: 19.03.1. Latest validated version: 18.09
</code></pre>

<p>running on CentOs7 minimal, installation on master seems good </p>

<pre><code>[rbo@K8SMaster ~]$ kubectl get nodes
NAME        STATUS   ROLES    AGE   VERSION
k8smaster   Ready    master   8h    v1.15.3
</code></pre>

<p>Thaks for help</p>

rab
<p>So, we found the issue wasn't related to unsupported Docker version but to missing Firewalld open port <code>6443</code> on <em>Master</em> node: you can solve it using the simple command <code>firewall-cmd --permanent --add-port=6443/tcp</code> along with a <code>firewall-cmd --reload</code>.</p>

<p>After that, the node joined as expected but <code>&lt;none&gt;</code> role is attached and that's <a href="https://github.com/kubernetes/kubernetes/issues/55232#issuecomment-342471004" rel="nofollow noreferrer">expected</a>: you have to follow <a href="https://stackoverflow.com/a/48856238/10104472">this solution</a> in order to mark the node as <em>worker</em> using the key-value label <code>node.kubernetes.io/role=worker</code> </p>
