[PATCH 0/5] Support service activation through Upstart

[Lennart Poettering]

On Sat, 25.12.10 01:35, Scott James Remnant (scott at netsplit.com) wrote:

> > It's not functionally different from dbus launching it really.
> >
> That's actually why I want to pass the Exec and User lines over to
> Upstart, because then we can do exactly this by default.  Though I
> would rather we didn't pass a path across like that, there's no
> guarantee that init and d-bus are even in the same filesystem
> namespace, for example.

Ugh.

One part of the reasoning for the redefinition of the session/user bus
was actually to declare explicitly that people can assume to have access
to the same FS on both sides of the user and the system bus. I think it
is a great advantage if everybody can rely on that sending path names
across the bus is safe and useful. A lot of software is built on passing
file names around (local crawlers like tracker for obvious reasons for
example) and I think rightfully so.

Losing yourself in namespacing games and trying to support usecases that
don't even exist is quite a waste of time in my eyes, with little
benefit for people who want to use D-BUs and write efficient
applications.

Whether both sides of the bus have access to the same FS is (besides
simplicity) mostly a question of efficiency: if they don't then you must
provide some alternative way to pass along the file contents, since a
reference of a file is seldomly useful without access to the file
itself. But transferring files over non-FS transports is necessarily
ineffective.

> The orthogonal question is then whether D-Bus should also send the
> activation request when it doesn't have a .service file?

No. That would be incompatible with the spec, as you can enumerate
activatable-but-not-activated services according to the spec.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.