title: How do I expose my service to the internal docker network?
body: <p>I'm running a group of services like this:</p>
  
  <pre><code>version: '2'
  services:
    web:
      build: ./web
      ports: 
        - "3000:3000"
      links:
        - api
    api:
      build: ./api
      links:
        - db
    db:
      image: postgres
  </code></pre>
  
  <p>I want to expose the <code>web</code> service to the host's network interface, binding port 3000 on the host to port 3000 on the container. BUT, i only want to expose the <code>api</code> service to the internal network, meaning i only want it to be reachable by the web service. IIRC, that means i need to expose the <code>api</code> service to the <code>bridge</code> network in the docker-compose file.</p>
  
  <p>If I was running the docker-cli, i'd do this by specifying the <code>--net bridge</code> argument. But I'm not sure how to do this in a compose file. Please help!</p>