anchor.diff:  
   ENV COPY_REFERENCE_FILE_LOG $JENKINS_HOME/copy_reference_file.log
   
  -USER jenkins
  +USER ${user}
   
   COPY jenkins.sh /usr/local/bin/jenkins.sh
   ENTRYPOINT ["/bin/tini", "--", "/usr/local/bin/jenkins.sh"]
  
positive.code:   && echo "$JENKINS_SHA /usr/share/jenkins/jenkins.war" | sha1sum -c -
  
  ENV JENKINS_UC https://updates.jenkins-ci.org
  RUN chown -R jenkins "$JENKINS_HOME" /usr/share/jenkins/ref
  
  # for main web interface:
  EXPOSE 8080
  
negative.code: ENV JENKINS_HOME /var/jenkins_home
  ENV JENKINS_SLAVE_AGENT_PORT 50000
  
  ARG user=jenkins
  ARG group=jenkins
  ARG uid=1000
  ARG gid=1000
  
  # Jenkins is run with user `jenkins`, uid = 1000
  # If you bind mount a volume from the host or a data container, 
  # ensure you use the same uid
  RUN groupadd -g ${gid} ${group} \
      && useradd -d "$JENKINS_HOME" -u ${uid} -g ${gid} -m -s /bin/bash ${user}
  
  # Jenkins home directory is a volume, so configuration and build history 
  # can be persisted and survive image upgrades
  