title: can't ssh to docker container of jenkinsci/ssh-slave
body: <p>I'm using the docker image of <a href="https://github.com/jenkinsci/docker-ssh-slave" rel="nofollow">jenkinsci/ssh-slave</a>
  First I generated a key on my machine:</p>
  
  <pre><code>ssh-keygen
  </code></pre>
  
  <p>I paste the content of my public key in my docker run command so it looks like:</p>
  
  <pre><code>$ docker run jenkinsci/ssh-slave "ssh-rsa AAAAB3NzaC1yc2EAAAADA.."
  </code></pre>
  
  <p>When the container is running I try to connect (as root user and as jenkins user). First I need to get the container IP:</p>
  
  <pre><code>$ docker inspect 65ebc0f67879 | grep IP
  
  172.17.0.x
  </code></pre>
  
  <p>I try to ssh:</p>
  
  <pre><code>$ ssh -i id_rsa root@172.17.0.x
  </code></pre>
  
  <p>But <code>Permission denied (publickey).</code>
  What am I doing wrong?
  When I <code>exec</code> the container I see my public key in the <code>authorized_keys</code>: </p>
  
  <pre><code>cat /home/jenkins/.ssh/authorized_keys
  </code></pre>
  
  <p>content: </p>
  
  <pre><code>ssh-rsa AAAAB3NzaC1yc2EAAAADA..
  </code></pre>