distro: add sysusers.d file

[bluca]

sysusers.d config files allows a package to use declarative configuration instead of manually written maintainer scripts.
The distro/common/knot.service unit file uses User=knot and Group=knot so the user/group need to be created before it can be started, and this takes care of it automatically.
This also allows image-based systems to be created with /usr/ only, and also allows for factory resetting a system and recreating /etc/ on boot.

https://www.freedesktop.org/software/systemd/man/latest/sysusers.d.html

[salzmdan]

Thanks! I will take a look. It must work with all the distributions that we support.

[bluca]

Thanks! Yeah it's paired with the systemd unit file, so it will work on all distros where that one works (and probably more, there's an independent sysusers.d reimplementation as well in some places)

[salzmdan]

FYI I did a test https://gitlab.nic.cz/knot/knot-dns/-/commit/8b7b54193cd6d76c52b068b94f6710998c3fe2de but it still needs more ❤️ https://gitlab.nic.cz/knot/knot-dns/-/pipelines/145792 😓

[bluca]

Thanks for looking into it, my idea here was to provide only something very basic, but if you are looking for a more complete integration, please check what I have sent as a MR for the debian package: https://salsa.debian.org/dns-team/knot-dns/-/merge_requests/14

[salzmdan]

Nice. We try to synchronize the salsa packaging and our distro packaging.
I think you should create a group knot as well (if I understand the syntax correctly). It's very convenient.

[bluca]

Yeah the sysusers u entry creates both a user and a group by default so that should be covered