[PATCH 0/5] Support service activation through Upstart

Lennart Poettering mzqohf at 0pointer.de
Sat Dec 25 08:08:11 PST 2010

On Sat, 25.12.10 10:44, Colin Walters (walters at verbum.org) wrote:

> > We also thought of getting rid of D-Bus service files entirely and
> > replace them completely with systemd service files, but that is really
> > hard since D-Bus reads all services files on boot-up and is able to
> > offer a list of bus-activatable services to clients. systemd is
> > optimized never to load unreferenced service files, so things are
> > fundamentally incompatible here in regards to enumertion of
> > services.
> Sure, but ListNames is similar to "systemctl --all" in that it's
> something for system administrators and debugging/developer tools.  If
> anything in the OS is calling ListNames during bootup e.g. I'd call
> that a bug.

I know that at least Rygel calls it to find possible backends. It will
enumerate all active and all activatable services whose name starts with
a particular prefix and will expose them via upnp. That way if you want
to share some stream with upnp from your app all you need to do is drop
an activation file into the dbus service dir and you will be started at
the right time and found with no need for any further registry.

(And I am to blame for this, i wrote that logic into the mediaserver
spec that rygel uses)

> > The current tandem of D-Bus serivce files AND systemd service
> > files for the same services is suboptimal, but appeared the most
> > sensible thing for now, especially during the transition period where
> > non-systemd systems are still common and matter. I think as soon as
> > sysvinit and Upstart have been phased out on most distros we can rethink
> > what we can do in this area.
> I thought we were discussing the future here =)  So it makes sense to
> work out how we expect all of this to work long term.

I think the smartest thing in the long run is probably to make systemd
service files the only source of configuration, and deprecate bus
.service files (at least on Linux). But well, I guess Scott doesn't like
this idea...


Lennart Poettering - Red Hat, Inc.

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