Subject: Re: bug#54786: Installation tests are failing

From: Ludovic Courtès <[email-masked]>
Date: Thu, 02 Jun 2022 15:13:26 +0200

Hi Maxim,

Maxim Cournoyer <[email-masked]> skribis:

> Ludovic Courtès <[email-masked]> writes:

[...]

>> Before going further, I’d like to understand: this does more than just
>> fix the Jami system tests, right?
>>
>> It would have been nice to have surgical changes to “just” fix the
>> tests, along the lines of <https://issues.guix.gnu.org/54786#9>,
>> possibly followed by a rework of the whole machinery, if that’s
>> possible.
>
> It's not really possible unfortunately, because the rework from talking
> to the D-Bus API via the 'dbus-send' binary to using Guile AC/D-bus was
> needed or at least simplified fixing the issues.

So am I right that the “issues” were not specifically related to the
Shepherd 0.9.0 switch, or at least not just to that?  (Just to make sure
I understand the context.)

>> Besides, I think we should talk to Jami upstream (which shouldn’t be too
>> hard :-)).  It doesn’t seem reasonable to me to have 800+ lines of code
>> in the distro to start one service.  Usually the ‘start’ and ‘stop’
>> methods are between 2 and 10 lines of code.
>>
>> What do you think is missing upstream so that starting Jami is
>> simpler?
>
> 1) Lack of D-Bus support in Shepherd to easily start D-Bus services.
> The upstream systemd service definition for the Jami daemon (jamid) is
> this:
>
> # net.jami.daemon.service
> [D-BUS Service]
> Name=cx.ring.Ring
> Exec=@LIBDIR@/jamid
>
> But that's nearly not where the complexity of our jami-service-type
> lies.

But that should be fine: we have dozens of D-Bus services that happily
get started by dbus-daemon.

> Rather, it's in the following:
>
> 2) The lack of a way to declaratively configure Jami and the need to use
> D-Bus API to issue commands to Jami non-interactively.  For example, to
> have Jami import an account it's necessary to go via either
>
> a) the GUI or
> b) the D-Bus API
>
> The Jami service in Guix makes use of b), which introduces the need for
> some Scheme bindings wrapping the low-level D-Bus interface.  Perhaps
> such bindings could live in Jami itself.
>
> The second point (2) could be addressed upstream, but since it's a
> rather niche use case (the common use case is simply running the client
> GUI), is already achievable via D-Bus, and would probably require a
> considerable amount of work in Jami itself, I think we can keep it as is
> for now, as a Guix System exclusive feature ;-).  Note that even if Jami
> could be configured via configuration files, we'd still want to be able
> to communicate with it via D-Bus to maintain the possible actions
> currently available in our Shepherd service (listing/enabling/disable
> accounts, etc.), so it'd only really help to reduce the start slot, and
> that's it.  We'd still need most of the D-Bus bindings, so it wouldn't
> help that much anyway.

Ah I see.

> I hope that clarifies how our jami-service-type is both complex but also
> unique.

Sure, the ability to configure Jami in a declarative and stateless
fashion is a plus, that’s really cool.

Longer-term I think this should go in Jami proper though.  It’s great
that Guix has an edge over the competition :-), but having to maintain
it is less nice.

Also, in more concrete terms: one goal of the least-authority work at
<https://issues.guix.gnu.org/54997> is to remove
‘make-forkexec-constructor/container’ and the whole (gnu build shepherd)
module.  Jami is one of its last remaining users (adjusting it felt like
beyond my abilities, precisely because it’s much more complex than the
other services I adjusted).

Could you take a look at that eventually, once this patch has been
reviewed?

Thanks,
Ludo’.