title: Container command could not be invoked
body: <p>Just encountered this error message while trying to bring up a docker-compose stack on my local machine. I have a Dockerfile which is identical to the official Wordpress image. My docker-compose file looks like this:</p>
  
  <pre><code>wordpress:
    image: joystick/wp
    ports:
      - "8000:80"
    links:
      - wordpress_db:mysql
    environment:
      - WORDPRESS_DB_HOST=mysql
      - WORDPRESS_DB_NAME=wordpress
      - WORDPRESS_DB_USER=admin
      - WORDPRESS_DB_PASSWORD=password
  wordpress_db:
    image: tutum/mysql
    environment:
      - ON_CREATE_DB=wordpress
      - MYSQL_PASS=password
  </code></pre>
  
  <p>When I change the "image" part at the beginning of this to "wordpress" and use the official image, everything comes up as I'd expect. But when I try to build my own image first, and then use it in this docker-compose file, I get the error message "Container command could not be invoked".</p>
  
  <p>I tried adding a "command" node into the "wordpress" section of this docker-compose, but that did not work.</p>