title: overlayfs inside docker container
body: <p>Is it possible to mount an overlay fs inside a (privileged) docker container? At least my intuitive approach, which works fine outside of a container, fails:</p>
  <pre><code>&gt; mkdir /tmp/{up,low,work,merged}
  &gt; mount -t overlay overlay -o lowerdir=/tmp/low/,upperdir=/tmp/up/,workdir=/tmp/work/ /tmp/merged/
  mount: /tmp/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error.
  </code></pre>
  <p>Additional information:</p>
  <ul>
  <li>Docker version 18.09.1, build 4c52b90</li>
  <li>Kernel 4.19.0-8-amd64</li>
  <li>Debian 10 (host and docker-image)</li>
  </ul>