title: domain configuration in docker-compose
body: <p>How to configure hostnames with domains in <code>docker-compose.yml</code>?</p>
  
  <p>Let's say the service <code>worker</code> expects the service <code>web</code> on the <code>http://web.local/</code> address.  But <code>web.local</code> doesn't resolve to an ip address no matter what I configure using the <code>hostname</code> directive. Adding an <code>extra_hosts</code> directive doesn't work either as I should know the ip of the service <code>web</code> for that, which I don't as it is assigned by docker. </p>
  
  <p>docker-compose.yml:</p>
  
  <pre><code>version: '3'
  services:
    worker:
      build: ./worker
      networks:
        - mynet    
    web:
      build: ./web
      ports:
        - 80:80
      hostname: web.local
      networks:
        - mynet
  networks:
    mynet:
  </code></pre>
  
  <p>but <code>ping web.local</code> doesn't resolve inside the service <code>worker</code></p>