anchor.diff:  # Base stage for building gems
   FROM        ruby:2.5-buster as bundle
  -
  +LABEL       stage=build
   RUN     echo "deb http://deb.debian.org/debian buster-backports main" >> /etc/apt/sources.list && \
           apt-get update && apt-get upgrade -y build-essential \
            && apt-get install -y --no-install-recommends \
  
positive.code: 
  # Base stage for building final images
  FROM        ruby:2.5-slim-buster as base
  RUN         echo 'APT::Default-Release "stretch";' > /etc/apt/apt.conf.d/99defaultrelease \
           && echo "deb     http://ftp.us.debian.org/debian/    testing main contrib non-free"  >  /etc/apt/sources.list.d/testing.list \
           && echo "deb-src http://ftp.us.debian.org/debian/    testing main contrib non-free"  >> /etc/apt/sources.list.d/testing.list \
  
negative.code: 
  # Build production image
  FROM        base as prod
  LABEL       stage=final
  COPY        --from=assets --chown=app:app /home/app/avalon /home/app/avalon
  COPY        --from=bundle-prod --chown=app:app /usr/local/bundle /usr/local/bundle
  
  