title: Why does using DOCKER_OPTS="--iptables=false" break the DNS discovery for docker-compose?
body: <p>When I add this line to my /etc/default/docker</p>
  
  <pre><code>DOCKER_OPTS="--iptables=false"
  </code></pre>
  
  <p>then the DNS no longer works. A group of containers started by docker compose no longer able to find each other:</p>
  
  <pre><code>version: '2'
  services:
      elasticsearch:
         image: elasticsearch:latest
         volumes:
            - ./esdata:/usr/share/elasticsearch/data
      kibana:
         image: kibana:latest
         environment:
            - ELASTICSEARCH_URL=http://elasticsearch:9200
  </code></pre>
  
  <p>The above stops working when iptables=false is set. The kibana container is not able to 'find' the elasticsearch container. But when removed (and docker engine restarted) then this works fine.</p>
  
  <p>Why is this?</p>
  
  <p>(and more to the point, why is iptables=false not the default setting when ufw is used??)</p>
  
  <p>thanks</p>