Re: systemd as external dependency

[Lennart Poettering <mztabzr 0pointer de>]

On Wed, 18.05.11 14:39, Frederic Peters (fpeters gnome org) wrote:

> 
> Lennart Poettering wrote:
> 
> > I'd like to propose systemd (GPL2+,
> > http://www.freedesktop.org/wiki/Software/systemd) as blessed external
> > dependency for GNOME 3.2. 
> 
> There actually isn't a module proposal period anymore.  We are using
> feature or design proposals now.  But the process for external
> dependencies was different anyway.
> 
> Recently I was trying to categorise our 2.x external dependencies,
> thinking about the way to handle this for 3.x, and came with three
> levels:
> 
> ** 1st level **
> 
>   Established, stable, system modules, they have been in
>   place for a long time, with stable API and ABI, and they exist in
>   sufficient versions in the distributions commonly used by GNOME
>   hackers, even in older but still used versions (Fedora 13 for
>   example).
> 
>   Examples : libxml2, libpng, dbus...
> 
>   Proposed guideline : mentioned as dependencies with a base version,
>   not built by default by jhbuild.
> 
>   Rationale : we want to reduce the number of modules that need to be
>   built to start developing on GNOME.
> 
> 
> ** 2nd level **
> 
>   Modules developed outside GNOME, with little attention to our
>   schedule, but with an active development, and where we want to track
>   recent code.
> 
>   Examples : mozilla (js-185 nowadays), poppler.
> 
>   Proposed guideline : built from tarballs, version bumps whenever a
>   module need a new version.
> 
>   Rationale : we need recent code, but we do not want to arrive on a
>   release days with modules failing to build because they require some
>   code only available in $DVCS.
> 
> 
> ** 3rd level **
> 
>   Modules developed outside GNOME, with attention to our schedule
>   (i.e. we can ask for a tarball and get it in two days).
> 
>   Examples : webkitgtk, polkit.
> 
>   Proposed guideline : treated like any other GNOME module, built from
>   latest git.
> 
>   Rationale : we do not need to put extra burden on modules that are
>   close to us.
> 
> 
> At which level would you see systemd integrated, now, and in the
> future?

Not sure. Depends. systemd is not fully established yet, but it
definitely is a system component, and yes, I do keep an eye on GNOME
schedules.

In the long run I hope that systemd takes a position next to
D-Bus. i.e. outside of GNOME, shared with other systems, a basic OS
building block, but pretty close to GNOME.

> Also you are speaking about (D-Bus) interfaces, and it is already
> envisioned to have them implemented by other components, should we
> talk about D-Bus interfaces that we expect to be available for GNOME,
> instead of saying "systemd"?

Really depends. In some cases dbus interface is fine (for example for
the mechanisms). In some other cases not so much, for example replacing
CK in gdm will be a different kind of interface.

> Something else is the ability to run development GNOME, the most
> common tool those days is jhbuild, which was created way before D-Bus,
> and it's not always straightforward to get it working with D-Bus
> services, do you believe it will be possible to have systemd built and
> useful from jhbuild, or do you expect systemd will have to come from
> the distribution?

systemd is something that needs to be adopted in the distribution, with
some exceptions.

The session management stuff will only work on a systemd system (since
it requires the cgroup hierarchy set up for it to work). There are a few
exceptions though, like the time/locale/hostname mechanisms which should
run without systemd around.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.