title: App in Docker does not update
body: <p>I am trying to run a simple Flask application inside docker. But it seems like even when I update my app.py code and restart the docker container nothing updates.</p>
  
  <p>I am running docker on OS X. IS this something simple I am missing or this is an expected behavior?</p>
  
  <p>This is what my docerfile looks like:</p>
  
  <pre><code>FROM ubuntu:14.04.3
  
  # install dependencies
  RUN apt-get update
  RUN apt-get install -y nginx
  RUN apt-get install -y supervisor
  RUN apt-get install -y python3-pip
  
  # update working directories
  ADD ./app /app
  ADD ./config /config
  ADD requirements.txt /
  
  # install dependencies
  RUN pip3 install -r requirements.txt
  
  # setup config
  RUN echo "\ndaemon off;" &gt;&gt; /etc/nginx/nginx.conf
  RUN rm /etc/nginx/sites-enabled/default
  
  RUN ln -s /config/nginx.conf /etc/nginx/sites-enabled/
  RUN ln -s /config/supervisor.conf /etc/supervisor/conf.d/
  
  EXPOSE 80
  CMD ["supervisord", "-n"]
  </code></pre>