Allow enabling services declaratively

[JustSoup312]

Currently, the way that OpenRC services are enabled by default in postmarketOS is by running a post-install on packages that runs rc-update add ____ for each service to be enabled. This works for system services, but user services do not work with this model as they are expected to be run by the user, which doesn't work when running a package manager as root.

An idea to get around this and to make pre-enabling services simpler is to create a declarative way to enable services. The idea is to use something similar to systemd presets or perhaps similar to how runit enables services (symlinking them to a folder that enables them). I would be partial to the systemd preset style as it would logically separate what packages enable which service.

The idea would be that OpenRC would read from a file to determine which services to start, then check if the user manually disabled any of the services and only start the services listed in the file, then start the imperatively started services.

[navi-desu]

symlinking them to a folder that enables them

ftr this is already how openrc works, ~/.config/rc/runlevels/$runlevel/$svc -> /etc/user/init.d/$svc, this is all that rc-update does as well

either way, hardcoding such symlink would still be an issue because $XDG_CONFIG_DIR is a thing, so i'm not against a preset-like functionality, if we manage to design it properly

[JustSoup312]

I thought that was how it worked, but I couldn't find info on it in the docs, so I just added that in.

On the design, what would you want out of it? Would it make sense to pretty much just copy the systemd design or make something new?

[forestbeasts]

Hmm, what about just having e.g. /etc/user/runlevels? Then openrc would start a user service if it's in either your local ~/.config runlevel or the /etc/user one.

Disabling services could maybe be implemented by symlinking them to /dev/null in your user runlevel (which I think is what systemd does when you disable a system service, with /etc/systemd/system/blahblah.target.wants/whatever -> /dev/null while /usr/lib/systemd/system/whatever has the original).

-- Frost

[navi-desu]

i've been considering that, not for this issue but i guess it'd work

#942 gives us a list of directories to do searches on, the problem then is just that openrc assumes there's a single unique runlevel directory in a lot of places

i'll play around with it after i fix master (it's kinda broken atm, idk why yet) and implement tests

if it goes well, it could get into a release later this month