title: How to automatically update your docker containers, if base-images are updated
body: <p>Say I have a trivial container based on the <code>ubuntu:latest</code>. Now there is a security update and <code>ubuntu:latest</code> is updated in the docker repo .</p>
  
  <ol>
  <li><p>How would I know my local image and its containers are running behind? </p></li>
  <li><p>Is there some best practice for automatically updating local images and containers to follow the docker repo updates, which in practice would give you the same niceties of having unattended-upgrades running on a conventional ubuntu-machine</p></li>
  </ol>