title: Docker link to previously started containers
body: <p>I'd like to carry out a one shot <code>docker-compose run</code> that will run against some previously started containers. My docker-compose.yml file will look like this:</p>
  
  <pre><code>one_shot_service:
   ...
    links:
      - long_running_service:docker
  long_running_service:
    ...
  </code></pre>
  
  <p>My workflow is:</p>
  
  <ol>
  <li>Start the long running service
  <code>docker-compose up long_running_service</code></li>
  <li>Run the one shot service multiple times. <code>docker-compose run --no-deps one_shot_service</code></li>
  </ol>
  
  <p>When I do this the <code>/etc/hosts</code> file on the <code>one_shot_service</code> does not contain an entry for docker. When I run without <code>--no-deps</code> it's fine. The reason I don't want to run without <code>no-deps</code> is beause the <code>long_running_service</code> takes a long time to start up.</p>
  
  <p>So long story short, how can I link to existing containers?</p>