You can walk backward in DockerFile. You can uninstall/cleanup "groups" "packages" to slim down. You can create your custom minimal image from that cloud image.It is like just a snapshot of a specific image at some point.

This is the minimal position. This is when the baby is born.

[docker pull hello-world][1]


[Dockerfile-linux.template][2]

You may want to look at kickstart/preseed if you want deep-diving.It is about being an official image or some image on which you have full control.
][2]


  [1]: https://hub.docker.com/_/hello-world/
  [2]: https://github.com/docker-library/hello-world/blob/master/Dockerfile-linux.template