title: docker: pass arguments to entrypoint
body: <p>If I have a super-dumb dockerfile, like this:</p>
  
  <pre><code>FROM ubuntu:latest
  ENTRYPOINT echo
  </code></pre>
  
  <p>Is it possible to pass arguments to the ENTRYPOINT, so that it will print whatever argument I pass?  I tried <code>docker build -t test . &amp;&amp; docker run test foo</code> but I just got an empty line.</p>