What happens when a volume links an existing populated host and container dir
<p>I've searched the docs but nothing came up so time to test it. But for a quick future reference...</p>

<p>Is the host folder populated with the container folder contents?</p>

<p>Is it the opposite?</p>

<p>Are both folder contents merged? (In that case: What happens when a file with the same name is in both folders?)</p>

<p>Or does it produce an error? Is the error thrown on launch or is it thrown when you try to build an image with a VOLUME pointing to an existing populated folder on the container?</p>

<p>Also, another thing that isn't in the docs: Do I have to define the container path as a VOLUME in the Dockerfile in order to use -v against it when launching the container or can I create volumes on the fly?</p>