title: Docker linked containers, Docker Networks, Compose Networks - how should we now 'link' containers
body: <p>I have an existing app that comprises of 4 docker containers running on the same host. They have been linked together using the <code>link</code> command.</p>
  
  <p>However, after some upgrades of docker, the <code>link</code> behaviour has been deprecated, and changed it seems. We are having issues where containers are loosing the link to each other now.</p>
  
  <p>So, docker says to use the new <code>Network</code> feature over <code>link</code>ed containers.  But I can't see how this works.</p>
  
  <p>If 2 containers are in the same network, are the same <code>ENV</code> vars automatically exposed on the containers as if they were linked? </p>
  
  <p>Or is the hosts file updated with the correct container name / ip addresses ? Even after a <code>docker restart</code> ? </p>
  
  <p>I can't see in the docs how a  container can find the location of another in its network?</p>
  
  <p>Also, <code>compose</code> looks to have a simple set up for linking containers, and may automate some of this - would compose be the way to go for defining multi container apps? Or is it too soon to run it in production?  </p>
  
  <p>Does <code>compose</code> support multiple host configuration as well?</p>
  
  <p>at some point in the future we will probably need to move one of the containers to a different host....</p>