title: Docker creates files as root in mounted volume
body: <p>I'm using Docker (1.3.1) to build RPMs inside a container:</p>
  
  <pre><code>docker run -v /home/matt/build:/build build-rpm /build/build-pkg.sh
  </code></pre>
  
  <p>This works fine (my user is in the <code>docker</code> group, so I don't need to sudo) and drops a completed <code>.rpm</code> file in the current directory. The problem is that the file is created as owned by root. </p>
  
  <p>How can I arrange it so that the file is created owned by the same user as I run docker with?</p>