title: Docker installed with snap in Ubuntu 19.04 won't stay started
body: <p>I installed docker via snap in Ubuntu.  It worked fine until I rebooted.  Since reboot, it won't stay started.</p>
  
  <p>So we start the daemon manually:</p>
  
  <pre><code>$ sudo snap start docker
  Started.
  </code></pre>
  
  <p>Cool.  Looks started to me.</p>
  
  <pre><code>$ docker run hello-world
  docker: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?.
  See 'docker run --help'.
  </code></pre>
  
  <p>Nope.  Nope it was not.</p>
  
  <p>What's going on and how do I fix it?</p>
  
  <p>I would like to be able to start it manually, and also for it to start automatically at login.</p>