title: What does it mean that `docker run --network=container:CONTAINERID`?
body: <p>I know that when running a container, I could set the <code>--network</code> argument whose value could be any from the results of <code>docker network ls</code>.<br>
  However, I have seen that some run containers like this:  </p>
  
  <pre><code>$ docker run --network=container:CONTAINERID IMAGE
  </code></pre>
  
  <p>I have searched this usage but got no docs to explain it.</p>
  
  <p>I have done some experiments and find that the container using another container's network shares the same network stack and it seems that the two containers are on the same <code>host</code> and they could call each other using <code>localhost</code>. </p>
  
  <p>So when running a container by setting <code>--network=container:CONTAINERID</code>, does it mean that the two containers share the same network stack?</p>