anchor.diff:  # Build production gems
   FROM        bundle as bundle-prod
   LABEL       stage=build
  +LABEL       project=avalon
   RUN         bundle install --without development test --with aws production postgres
   
   
   # Install node modules
   FROM        node:12-buster-slim as node-modules
   LABEL       stage=build
  +LABEL       project=avalon
   RUN         apt-get update && apt-get install -y --no-install-recommends git
   COPY        package.json .
   COPY        yarn.lock .
  
positive.code: # Build production assets
  FROM        base as assets
  LABEL       stage=build
  COPY        --from=bundle-prod --chown=app:app /usr/local/bundle /usr/local/bundle
  COPY        --chown=app:app . .
  COPY        --from=node-modules --chown=app:app /node_modules ./node_modules
  
negative.code: # Base stage for building final images
  FROM        ruby:2.5-slim-buster as base
  LABEL       stage=build
  LABEL       project=avalon
  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 \
  