anchor.diff:  
   # redis
   RUN rm /etc/service/redis/down
  +
  +# upgrade passenger
  +RUN apt-get update
  +RUN apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" upgrade
  +
  +# native passenger
  +RUN setuser app ruby2.2 -S passenger-config build-native-support
   
   # setup gems
   WORKDIR /tmp
  
positive.code: RUN /pd_build/nodejs.sh
  RUN /pd_build/redis.sh
  
  # native passenger
  RUN setuser app ruby2.2 -S passenger-config build-native-support
  
  # nginx
  RUN rm /etc/service/nginx/down
  RUN rm /etc/nginx/sites-enabled/default
  
negative.code: RUN chown app Gemfile
  RUN chown app Gemfile.lock
  
  # cleanup apt
  RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  
  