Singularity.fun

Bootstrap: debootstrap
OSVersion: bionic
MirrorURL: http://us.archive.ubuntu.com/ubuntu/

%help
  A container with a bunch of fun programs installed.

%environment
  export LC_ALL=C.UTF-8
  export LANG=C.UTF-8
  export PATH=/usr/games:"$PATH"

%post
  apt update
  apt install -y software-properties-common
  apt-add-repository universe
  apt update

  # this sets an env variable only for this apt command
  DEBIAN_FRONTEND=noninteractive apt install -y cmatrix cowsay fortune
  echo "export PATH=/usr/games:$PATH" >> "$SINGULARITY_ENVIRONMENT"

# tests don't have access to the env variables that you set for the container, you have to set them again
%test
  export PATH=/usr/games:"$PATH"
  command -v cowsay >/dev/null 2>&1 || \
    { echo >&2 "I require cowsay but it's not installed.  Aborting."; exit 1; }
  command -v fortune >/dev/null 2>&1 || \
    { echo >&2 "I require fortune but it's not installed.  Aborting."; exit 1; }
  command -v cmatrix >/dev/null 2>&1 || \
    { echo >&2 "I require cmatrix but it's not installed.  Aborting."; exit 1; }

%runscript
  if [ $# -eq 0 ]
    then
      fortune | cowsay
  else
    cowsay "$@"
  fi