anchor.diff:  # Clone Azrael from GitHub.
   RUN git clone https://github.com/olitheolix/azrael /demo/azrael
   
  -# Expose the webserver and ZeroMQ port.
  +# Expose the necessary Tornado and ZeroMQ ports.
   EXPOSE 8080 5555
   
  -# Export the /demo folder (this is where MongoDB stores its files and
  -# where Azrael puts its logs) to prevent Docker from tracking it via
  -# its Union FS.
  -VOLUME /demo
  -
  +# Home directory.
   WORKDIR /demo/azrael
   
  -#ENTRYPOINT ["/usr/bin/python3", "entrypoint.py"]
  -ENTRYPOINT ["/bin/bash"]
  +ENTRYPOINT ["/usr/bin/python3", "entrypoint.py"]
  +#ENTRYPOINT ["/bin/bash"]
   
   # Default command: start MongoDB and Azrael.
  -CMD ["-h"]
  +CMD ["./demo_forcegrid.py --noviewer --numcubes 4,4,1"]
  
positive.code: # Clean Build: docker build --rm=true --no-cache=true -t="<user>/<name>:<tag>" .
  # Incremental Build: docker build -t="<user>/<name>:<tag>" .
  # Run interactive: docker run -p 8080:8080 -ti "<user>/<name>:<tag>"
  # Run standalone: docker run -d -v /var -v /demo -p 8080:8080 <user>/<name>:<tag> "./demo_forcegrid.py --noviewer --numcubes 4,4,1"
  
  # Base image is Ubuntu 14.04
  FROM ubuntu:14.04
  MAINTAINER Oliver Nagy <olitheolix@gmail.com>
  
  
negative.code:     python3-tornado \
      python3-zmq
  
  # Install PIP packages, download and compile the Bullet-Python
  # bindings, and clean up to reduce the size of the container image.
  WORKDIR /tmp
  RUN apt-get install -y python3-pip && \
      pip3 install cytoolz setproctitle websocket-client==0.15 pymongo \
  