anchor.diff:  COPY docker/sources.list /etc/apt/sources.list
   
   # packages
  -RUN apt-get update && \
  -  apt-get install --assume-yes \
  +RUN apt-get update \
  +  && apt-get install --assume-yes \
       build-essential \
       curl \
       memcached \
       runit
   
   # imagemagick
  -RUN apt-get install --assume-yes \
  +RUN apt-get update \
  +  && apt-get install --assume-yes \
       inkscape \
       libbz2-dev \
       libfftw3-dev \
  
positive.code:   && rm -rf $(ls -d ruby-* | head -n 1)
  
  # varnish
  RUN apt-get install --assume-yes \
      apt-transport-https \
    && curl https://repo.varnish-cache.org/GPG-key.txt \
      | apt-key add - \
    && echo 'deb https://repo.varnish-cache.org/debian/ jessie varnish-4.1' \
      >> /etc/apt/sources.list.d/varnish-cache.list \
    && apt-get update \
    && apt-get install --assume-yes varnish
  COPY docker/default.vcl /etc/varnish/default.vcl
  RUN varnishd -C -f /etc/varnish/default.vcl
  COPY docker/varnish_defaults /etc/default/varnish
  
  # monit
  RUN apt-get install --assume-yes \
      libpam-dev \
    && curl https://mmonit.com/monit/dist/monit-5.16.tar.gz \
      | tar xz \
  
negative.code: 
  ENV RAILS_SERVE_STATIC_FILES true
  
  RUN apt-get update \
    && apt-get install --assume-yes \
      libpq-dev \
      libsqlite3-dev \
    && export LDFLAGS=-lMagickWand-6.Q16 \
  