Add easy way to add AUR packages to ParticleOS

[PhysicsIsAwesome]

Being able to use AUR packages is essential for many Arch users. It would be nice to have an easy way to add AUR packages to ParticleOS.

[LorbusChris]

related: systemd/mkosi#2578

[EpocSquadron]

It took me a long time to piece this together, but if you are building your particleOS from your particleOS, building AUR packages is problematic, as there may be build dependencies that it will try to install with pacman. Since you're running immutable, that won't work.

Fortunately, I stumbled on the devtools package, which is in the main arch repos and provides tooling for maintainers. One of those is pkgctl build, which will use a systemd-nspawn container to build packages! This is perfect for getting around the build dependencies problem. However, to set up the root filesystem for the nspawn command to use, you need to have a functioning sudo and pacman. This means adding to the tmpfiles.d/etc.conf to ensure /etc/pacman.conf, /etc/pacman.d/mirrorlist are symlinked or copied, and /etc/sudoers.d is created. You'll need to then actually configure them, and also to run pacman-key --init && pacman-key --populate in the host particleOS.

Once you have that set up, find your package on aur.archlinux.org, clone it with git, run pkgctl build, and then copy the .pkg.tar.zst into mkosi.packages and add them to your mkosi.local.conf's Packages array.

It may be possible to work this into the build step of the particleOS image, but that's beyond me as yet.

[PhysicsIsAwesome]

@EpocSquadron Interesting solution. I meant installing AUR packages directly into the immutable image of ParticleOS during build time.

[EpocSquadron]

That's what dropping the built packages into mkosi.packages does for you. mkosi makes the packages in that directory available for installation during build, so you just add their names to your Packages array to get them installed to the image. It's actually building those aur packages on the host that is tricky, and why i mentioned pkgctl as a solution.