Previously, if any unit had a socket associated with it, stc-ng
counted it as "socket-activated", meaning that the unit would get
stopped and the socket get restarted. That can wreak havoc on units
like systemd-udevd and systemd-networkd.
Instead, let units set the new flag notSocketActivated, which sets a
boolean on the unit indicating to stc-ng that the unit wants to be
treated like any other non-socket-activated unit instead. That will
stop/start or restart these units on upgrades, without unnecessarily
tearing down any machinery that the system needs to run.
This allows us to set things like dependencies in a way that we can
catch typos at eval time.
So instead of
```nix
systemd.services.foo.wants = [ "bar.service" ];
```
we can write
```nix
systemd.services.foo.wants = [ config.systemd.services.bar.name ];
```
which will throw an error if no such service has been defined.
Not all cases can be done like this (eg template services), but in a lot
of cases this will allow to avoid typos.
There is a matching option on the unit option
(`systemd.units."foo.service".name`) as well.
Until this commit, the documentation suggested `multi-user.target`
as `wantedBy` for all services.
Since `multi-user.target` is not available for user services,
propose a different default for those in the documentation.
Co-authored-by: Naïm Favier <n@monade.li>
Co-authored-by: Florian Warzecha <liketechnik@disroot.org>
conversions were done using https://github.com/pennae/nix-doc-munge
using (probably) rev f34e145 running
nix-doc-munge nixos/**/*.nix
nix-doc-munge --import nixos/**/*.nix
the tool ensures that only changes that could affect the generated
manual *but don't* are committed, other changes require manual review
and are discarded.
