Why do you think it isn't outlined? The website explains exactly what the modifications are, what they do, and what they are good for. The Dockerfile is on Gith

Why do you think it isn't outlined? The website explains exactly what the modifications are, what they do, and what they are good for. The Dockerfile is on Github for everyone to see. The website makes explicit mention that the init system is /sbin/my_init, for which the full source is available on Github. It's trivial to take the my_init script and integrate it into your non-Ubuntu container. You can even write your own init system based on the website description if you so choose.