Closes#169733
The issue is that Nextcloud fails to start up after a GC because the
symlink from `override.config.php` is stale.
I'm relatively certain that this is not a bug in the Nix GC - that
would've popped up somewhere else already in the past years - and one of
the reporters seems to confirm that: when they restarted
`nextcloud-setup.service` after the issue appeared, an
`override.config.php` pointing to a different hash was there.
This hints that on a deploy `nextcloud-setup` wasn't restarted properly
and thus replacing the symlink update was missed. This is relatively
hard to trigger due to the nature of the bug unfortunately (you usually
keep system generations for a few weeks and you'll need to change the
configuration - or stdenv - to get a different `override.config.php`),
so getting pointers from folks who are affected is rather complicated.
So I decided to work around this by using systemd-tmpfiles which a lot
of other modules already utilize for this use-case. Now,
`override.config.php` and the directory structure aren't created by
`nextcloud-setup`, but by `systemd-tmpfiles`.
With that, the structure is guaranteed to exist
* on boot, since tmpfiles are always created/applied then
* on config activation, since this is done before services are
(re)started which covers the case for new installations and existing
ones.
Also, the recursive `chgrp` was used as transition tool when we switched
from `nginx` as owning group to a dedicated `nextcloud` group[1][2], but
this was several releases ago, so I don't consider this relevant
anymore.
[1] fd9eb16b24
[2] ca916e8cb3
90787dbe89