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Simple build to exercise

Let's start with something easy and fast to build - Install the figlet app in a container.

$ figlet UPPMAX
 _   _ ____  ____  __  __    _    __  __
| | | |  _ \|  _ \|  \/  |  / \   \ \/ /
| | | | |_) | |_) | |\/| | / _ \   \  / 
| |_| |  __/|  __/| |  | |/ ___ \  /  \ 
 \___/|_|   |_|   |_|  |_/_/   \_\/_/\_\

 $ figlet -f slant UPPMAX
   __  ______  ____  __  ______   _  __
  / / / / __ \/ __ \/  |/  /   | | |/ /
 / / / / /_/ / /_/ / /|_/ / /| | |   / 
/ /_/ / ____/ ____/ /  / / ___ |/   |  
\____/_/   /_/   /_/  /_/_/  |_/_/|_|

Let's use Ubuntu from Docker to install the package.

figlet.def 
Bootstrap: docker
From: ubuntu:20.04
  • It is not necessary right now, but it is good to inform the package manager that we are not in a interactive session by export DEBIAN_FRONTEND=noninteractive
  • We need only to install the figlet package by apt-get. Do not forget to apt-get update first, since the package index is empty.
  • apt-get install -y figlet - use -y to avoid the confirmation when installing packages
  • In what section we add these commands?
  • Let's clean a bit with apt-get clean
figlet.def 
Bootstrap: docker
From: ubuntu:20.04

%post
  export DEBIAN_FRONTEND=noninteractive

  apt-get update
  apt-get install -y figlet
  apt-get clean
  • Let's define what to run when we run the container itself.
figlet.def 
Bootstrap: docker
From: ubuntu:20.04

%post
  export DEBIAN_FRONTEND=noninteractive

  apt-get update
  apt-get install -y figlet
  apt-get clean

%runscript
  figlet "$@"
  • Build the recipe
build 
$ sudo singularity build figlet.sif figlet.def