In Debian and derivative systems, there are many ways to build images. The simplest tool of choice is often debootstrap. It works by downloading the .deb files from a mirror and unpacking them into a directory which can eventually be chrooted into. More often than not, we want to make some customization on this image, install some extra packages, run a script, add some files, etc debos is a tool to make this kind of trivial tasks easier. debos works using recipe files in YAML listing the actions you want to perform in your image sequentially and finally, choosing the output formats.