anchor.diff:  
   #env vars
   RUN \
  -  mkdir -vp /etc/airstack && \
  +  set -e; mkdir -vp /etc/airstack; \
     echo $AIRSTACK_RUNTIME_VARS | jq '' | tee /etc/airstack/runtime.json
  -
   
   
   ################################################################################
  
positive.code: 
  # password set in sshd/run script at ssh start. allows for override via env var.
  RUN \
    set -e; groupadd --system airstack --gid 432 && \
    useradd --uid 431 --system --base-dir /home --create-home --gid airstack --shell /bin/nologin --comment "airstack user" airstack && \
    chown -R airstack:airstack /home/airstack
  
  # passwordless sudo enabled for airstack user. should only do for development environment.
  # RUN [ $AIRSTACK_TAGS_ENV = "development" ] && echo "airstack  ALL = NOPASSWD: ALL" > /etc/sudoers.d/airstack && usermod --shell /bin/bash airstack
  RUN \
    echo "airstack  ALL = NOPASSWD: ALL" > /etc/sudoers.d/airstack && \
    usermod --shell /bin/bash airstack
  
  #runit install
  
negative.code: # install commands
  # airstack core utilities
  ADD core /package/airstack/core
  RUN set -e; mkdir -v /command; ln -sv /package/airstack/core/command/* /command/
  
  # Try and have binaries that are modified less often up at top of this package section.
  
  