[PATCH 3/3] activation: optionally, use systemd for system bus activation

[Colin Walters]

On Wed, Jul 7, 2010 at 5:01 PM, Lennart Poettering <mzqohf at 0pointer.de> wrote:
>
> I actually like to keep everything on one bus. The bus is just a
> transport, and i see little need to split off a seperate connection only
> for the activation stuff.

To be clear - I wasn't suggesting a separate connection *just* for
activation stuff.  We could move system bus eavesdropping over to
that, for example.  People have also asked for interfaces to dump the
match rules from the bus, etc.  The point is that this interface would
be considered unstable/hidden, separate from org.freedesktop.DBus.

If we could go back in time, I'd put UpdateActivationEnvironment there.

> Note that keeping things on a single bus has a big advantage: the
> activation logic can be used for "activating" systemd itself.

I'll have to think about this a bit more.  But note you can do any
synchronization you want over a management interface too.

> To make it possible to boot the same system with systemd and without
> systemd: the systemd .service file would set --systemd-activation and
> thereby tell D-Bus that it should send activation requests to
> systemd. And the SysV init script would not set it, so that when D-Bus
> is started with a traditional init system this activation hookup would
> not happen.

Couldn't we just notice whether we were started with the systemd:
address family then?