anchor.diff:  # support NODEJS_VERSION as ARG to let the user switch between nodejs 6.x and 7.x
   # NODEJS_PACKAGE_MANAGER: you can, additionally to npm, install yarn; if you select yarn here
   # also, if yarn is selected, it would be used while running the base installation
  -ONBUILD ARG OPS_MODE
  +ONBUILD ARG DEV_TOOLS
   ONBUILD ARG APPLICATION_ENV
   ONBUILD ARG NODEJS_VERSION
   ONBUILD ARG NODEJS_PACKAGE_MANAGER
   
   
  -ONBUILD ENV OPS_MODE=${OPS_MODE:-production} \
  +ONBUILD ENV DEV_TOOLS=${DEV_TOOLS:-off} \
               APPLICATION_ENV=${APPLICATION_ENV:-production} \
               NODEJS_VERSION=${NODEJS_VERSION:-6} \
               NODEJS_PACKAGE_MANAGER=${NODEJS_PACKAGE_MANAGER:-npm}
  
positive.code:             && ./entrypoint.sh build_image \
              
              # install ops tools while in debugging and testing stage
              && [ "$OPS_MODE" = "production" ] || apk add vim less tree \
              
              # clean up if in production mode
              && [ "$OPS_MODE" = "development" ] || apk del .base_build_deps
  
negative.code: # 
  
  
  # With DEV_TOOLS=on, we won't clean up the image from build tools and debugging tools.
  # Even further we will add tools like vim, tree and less.
  # supported vaules are (on/off), defaults to "off"
  
  # application env decides in which mode the application is installed/runned.
  # so if you choose development here, e.g. composer and npm/yarn will also install
  