title: Rails server is still running in a new opened docker container
body: <p>I want to deploy my rails project using Docker. So I use Docker-Compose. But I get one weird error message. When run docker-compose up(this contains db-container with postgresql, redis and web container with rails) I get a </p>
  
  <p><code>web_1   | =&gt; Booting Puma
  web_1   | =&gt; Rails 4.2.4 application starting in production on http://0.0.0.0:3000
  web_1   | =&gt; Run</code>rails server -h<code>for more startup options
  web_1   | =&gt; Ctrl-C to shutdown server
  web_1   | A server is already running. Check /usr/src/app/tmp/pids/server.pid.
  web_1   | Exiting
  </code>
  So I cannot understand why do I get this message, because every time I run docker-compose up, new containers start, not the previous. Even if want to delete these <code>server.pid</code> I am not able to do that, because this container isn't running. </p>
  
  <p>my docker-compose.yml file</p>
  
  <pre><code>web:
    dockerfile: Dockerfile-rails
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    ports:
      - "80:3000"
    links:
      - redis
      - db
    environment:
      - REDISTOGO_URL=redis://user@redis:6379/
  
  redis:
    image: redis
  
  db:
    dockerfile: Dockerfile-db
    build: .
    env_file: .env_db
  </code></pre>
  
  <p>Dockerfile-rails</p>
  
  <pre><code>FROM rails:onbuild
  
  ENV RAILS_ENV=production
  </code></pre>
  
  <p>I don't think I need to post all my Dockerfiles</p>
  
  <p>UPD: I fixed it by myself: i just deleted all my containers and ran the <code>docker-compose up</code> once again</p>