[systemd-devel] Using systemd --user to manage graphical sessions?

[Martin Pitt]

Hello Mantas,

thanks for your reply!

Mantas Mikulėnas [2016-05-11 19:54 +0300]:
> AFAIK, the general idea of --user is that there's at most one graphical
> session (per user) at a time, so things like $DISPLAY naturally become per
> user.

Right, I understand that. But that doesn't mean that *always* have a
$DISPLAY. So simply having user units that start with systemd --user
does not work: If the first login is on a VT or through ssh these
would all fail, and if you then actually login on the DM nothing would
restart them.

That could be helped a bit with a ConditionHasEnvironment=DISPLAY or
something such, and an xinit.d script that restarts them. But this can
all be achieved through some good/bad hacks, my main issue is still
that you can't bind those to the system unit with the correct
lifecycle -- session-*.scope.

> I can start this with "systemctl --user start xeyes@${XDG_SESSION_ID}",
> > but this will hang off user at 1000.service instead of session-*.scope
> > and thus it will not be stopped once the X session gets logged out.
> >
> 
> Most X11 clients will exit as soon as the X server goes away, no?

They do, but you get failed units and scary error messages, and this
happens *after* the X session is already gone -- thus no way for them
to gracefully shut down.

> `systemctl --user import-environment DISPLAY` seems to work well enough.

Right, that part works fine, that's not the problem.

> In stock GNOME, I already have a bunch of bus-activated apps running off
> the user bus (dbus.service), such as gedit, nautilus, or gnome-terminal;
> the latter finally got its own gnome-terminal.service in 3.20.2.

gnome-terminal is what I looked at too, and what I referred to in the
bug report: https://bugzilla.gnome.org/show_bug.cgi?id=744736 -- this
is pretty broken right now :-( This is essentially one program trying
to work around (and failing) the fundamental issue that a lot of
things don't make sense to start with the first non-X login and keep
around until after the X session ends.

Thanks,

Martin

-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)