anchor.diff:  #-----------------------------------------------------------------------------#
   # Install PETSc to system path
   #-----------------------------------------------------------------------------#
  -ARG PETSC_REV
  +ARG PETSC_REV=a7279e6a5f0ea1f621d894c55a771197241f8708
   ARG PETSC_OPTIONS
   ENV PETSC_DIR=/usr/local
   COPY scripts/update_and_rebuild_petsc.sh ${MOOSE_DIR}/scripts/update_and_rebuild_petsc.sh
  
positive.code: # involve MOOSE, leading to unneccessary, redundant use of computing
  # resources, bandwidth, and storage.
  #
  # To build a MOOSE image, there are eight optional arguments and two required
  # arguments to be set using the --build-arg flag.
  #
  # DISTRO_NAME: Optional.  Linux distribution (ubuntu, centos)
  # DISTRO_VERSION: Optional with above (20.04, 8 respectively)
  # LIBMESH_METHODS: Optional. Methods with which to build libmesh; defaults to opt dbg.
  # MOOSE_JOBS: Optional.  Sets number of cores for running make.
  # MOOSE_METHODS: Optional. Methods with which to build MOOSE; defaults to opt.
  # PETSC_REV: Commit hash of submodule petsc.
  # PETSC_OPTIONS: Optional. Options to pass to update_and_rebuild_petsc.sh.
  # LIBMESH_REV: Commit hash of submodule libmesh.
  # LIBMESH_OPTIONS: Optional. Options to pass to update_and_rebuild_libmesh.sh.
  # BUILD_MODULES: Optional. Set to build all MOOSE modules.
  #-----------------------------------------------------------------------------#
  ARG DISTRO_NAME=ubuntu
  ARG DISTRO_VERSION=20.04
  
negative.code: #-----------------------------------------------------------------------------#
  # Install Libmesh to system path
  #-----------------------------------------------------------------------------#
  ARG LIBMESH_REV=09da24df01e50defd94bc4f7396f866a808ecea5
  ARG LIBMESH_OPTIONS
  ARG LIBMESH_METHODS="opt dbg"
  ENV LIBMESH_DIR=/usr/local \
  