documentation, best practices and examples

[theCalcaholic]

I'm using mkosi for about 7 months now for a project and I'm often encountering questions that I find hard to answer when it comes to implementation details.

One of the root issues is, that the mkosi documentation does an acceptable job in describing how mkosi works as an interface (i.e. what options and configuration settings do, how files and directories are interpreted, etc.) but it only scratches the surface when it comes to how I'm supposed to use it.

Some examples of questions I found hard to answer (not the main point of this discussion, please don't answer them here):

1. Is it a good idea, to use sub images to generate artifacts (rpms, system extensions, oci images, ...) that will be added to the fs tree of the main image? Should I do that kind of thing with mkosi at all or use an external (or wrapper) build system like make?
2. When I'm building some binary in a build script and fetch it's dependencies in a prepare script, what do I need to do in order to cache those dependencies when running in incremental mode? Is that even possible/meant to be used this way?

Maybe, this is by design, because mkosi strives to be very versatile and unopinionated in how it is being used.
If that's the case, it would be extremely helpful to have a curated set of example repositories of varying complexity that can be used to learn good usage practices.
If that's not the case, it would be amazing to have more documentation on how to use mkosi correctly - ideally in addition to those example projects.

For me personally, tremendously helpful projects were e.g. incus-os by @stgraber as well as systemd's own mkosi setup.