title: Add a volume to Docker, but exclude a sub-folder
body: <p>Supposed I have a Docker container and a folder on my host <code>/hostFolder</code>. Now if I want to add this folder to the Docker container as a volume, then I can do this either by using <code>ADD</code> in the <code>Dockerfile</code> or mounting it as a volume.</p>
  
  <p>So far, so good.</p>
  
  <p>Now <code>/hostFolder</code> contains a sub-folder, <code>/hostFolder/subFolder</code>.</p>
  
  <p>I want to mount <code>/hostFolder</code> into the Docker container (whether as read-write or read-only does not matter, works both for me), but I do <strong>NOT</strong> want to have it included <code>/hostFolder/subFolder</code>. I want to exclude this, and I also want the Docker container be able to make changes to this sub-folder, without the consequence of having it changed on the host as well.</p>
  
  <p>Is this possible? If so, how?</p>