title: docker-compose not adding hostname to /etc/hosts
body: <p>I'm working on a docker-compose config which should spin up an openvpn container attached to a dnsmasq container. The openvpn server should automatically discover the dnsmasq container and use it as the dns server. Discovery is done by searching for an entry "dnsmasq" in the /etc/hosts file.</p>
  
  <p>I have the following docker-compose.yml file:</p>
  
  <pre><code>version: '2'
  services:
    data:
      build: ./
    dnsmasq:
      cap_add:
        - NET_ADMIN
      hostname: dnsmasq
      image: &lt;dnsmasq image&gt;
      ports:
        - 53:53/udp
      restart: always
    openvpn:
      cap_add:
        - NET_ADMIN
      depends_on:
        - data
        - dnsmasq
      image: &lt;openvpn image&gt;
      ports:
        - 1194:1194/udp
      restart: always
      volumes_from:
        - data
  </code></pre>
  
  <p>I've specified "dnsmasq" as hostname for the dnsmasq container and expecting it to appear in "/etc/hosts" in the openvpn container. This doesn't seem to happen.</p>
  
  <p>This is a dump from /etc/hosts from within the openvpn container:</p>
  
  <pre><code>openvpn_1  | 127.0.0.1  localhost
  openvpn_1  | ::1    localhost ip6-localhost ip6-loopback
  openvpn_1  | fe00::0    ip6-localnet
  openvpn_1  | ff00::0    ip6-mcastprefix
  openvpn_1  | ff02::1    ip6-allnodes
  openvpn_1  | ff02::2    ip6-allrouters
  openvpn_1  | 172.19.0.4 d44a72f42ef9
  </code></pre>
  
  <p>I expect d44a72f42ef9 to be "dnsmasq".</p>
  
  <p>What am I doing wrong?</p>
  
  <p>I'm running docker-compose 1.8.1.</p>