title: Prevent Docker Compose from creating separate network
body: <p>I discovered that <a href="https://docs.docker.com/compose/" rel="nofollow">Docker Compose</a> places containers in a separate network when using <a href="https://docs.docker.com/compose/compose-file/#version-2" rel="nofollow">version 2</a> of their YAML syntax. This makes linking with existing containers difficult.</p>
  
  <p>Is there a way to prevent this, and revert to the behavior of <a href="https://docs.docker.com/compose/compose-file/#version-1" rel="nofollow">version 1</a>, without actually reverting?</p>