title: docker-compose can't find services or containers in Docker for Mac
body: <p>I have a docker-compose set up that starts a Rails web application and a PostgreSQL DB container.</p>
  
  <p>Both services start, but I need to run db:seed and db:migrate in the web application container (service = "web").</p>
  
  <p>I try to do this with:</p>
  
  <pre><code>docker-compose exec web rails db:seed
  </code></pre>
  
  <p>But it tells me:</p>
  
  <pre><code>ERROR: No container found for web_1
  </code></pre>
  
  <p>When I try with docker:</p>
  
  <pre><code>docker exec &lt;container-id&gt; rails db:seed
  </code></pre>
  
  <p>Docker does try to execute the command in the container, but it obviously fails, as docker has no knowledge of the PostgreSQL container and can't connect to it to execute the seed comand.</p>
  
  <p>This only appears to be an issue in Docker for Mac. It all works fine in Ubuntu. </p>
  
  <p>I am using Version 1.8.0 of docker-compose and 1.12.1 of docker.</p>