title: Can I have a writable Docker volume mounted under a read-only volume?
body: <p>I'm trying to mount a writable Docker volume as a child of a read-only volume, but I get this error:</p>
  
  <pre><code>ERROR: for wordpress  rpc error: code = 2 desc = "oci runtime error: 
  could not synchronise with container process: mkdir /mnt/sda1/var/lib
  /docker/aufs/mnt/.../var/www/html/wp-content/uploads: read-only file 
  system"
  </code></pre>
  
  <p>I'm working with a WordPress image, and the two volumes I want to mount are:</p>
  
  <ul>
  <li>/var/www/html/wp-content: Contains my development code.  Read-only, since I don't want any unexpected changes.</li>
  <li>/var/www/html/wp-content/uploads: Files that are uploaded by users.  Must be writable.</li>
  </ul>
  
  <p>The quick solution is to move <em>uploads</em> somewhere else, but I'd prefer a Docker solution.</p>
  
  <p>Relevant bits of my docker-compose.yml:</p>
  
  <pre><code>volumes:
    uploads:
      driver: local
  
  services:
    wordpress:
      volumes:
        - /dev/workspace/wp-content/:/var/www/html/wp-content/
        - uploads:/var/www/html/wp-content/uploads 
  </code></pre>