anchor.diff:  # will be used by attached slave agents:
   EXPOSE 50000
   
  -ENV COPY_REFERENCE_FILE_LOG $JENKINS_HOME/copy_reference_file.log
  +ENV COPY_REFERENCE_FILE_LOG ${JENKINS_HOME}/copy_reference_file.log
   
   USER ${user}
   
  
positive.code: 
  # Jenkins home directory is a volume, so configuration and build history 
  # can be persisted and survive image upgrades
  VOLUME /var/jenkins_home
  
  # `/usr/share/jenkins/ref/` contains all reference configuration we want 
  # to set on a fresh new installation. Use it to bundle additional plugins 
  
negative.code: 
  RUN apt-get update && apt-get install -y git curl zip && rm -rf /var/lib/apt/lists/*
  
  ENV JENKINS_HOME /home/jenkins/jenkins_data
  ENV JENKINS_USER_HOME /home/jenkins
  ENV JENKINS_SLAVE_AGENT_PORT 50000
  
  