title: Should I backup everything in /var/lib/docker?
body: <p>I'm currently running Docker 1.12.6 on Ubuntu 17.04, and I would like to know if all directories under <em>/var/lib/docker</em> should be included in my monthly backup (I backup everything under <em>/</em> with <code>rsnapshot</code>, and then set some <code>exclude</code> rules).</p>
  
  <p>With Vagrant, for example, I exclude from the backup downloaded images and their resulting machines (<em>.vagrant.d/boxes/</em> and <em>.VirtualBox/Machines/</em>), since they can be rebuilt anytime with their respective <em>Vagrantfile</em>.</p>
  
  <p>I don't really understand how the <code>/var/lib/docker</code> directory structure works, though. It is like the following in my system:</p>
  
  <pre><code># tree -L 2 -a -F --dirsfirst --noreport /var/lib/docker/
  /var/lib/docker/
  ├── aufs/
  │   ├── diff/
  │   ├── layers/
  │   └── mnt/
  ├── containers/
  ├── image/
  │   └── aufs/
  ├── network/
  │   └── files/
  ├── swarm/
  ├── tmp/
  ├── trust/
  └── volumes/
      └── metadata.db
  </code></pre>