GNU bug report logs - #55898
Services depending on new Shepherd features may fail until reboot

Previous Next

Full log

Message #51 received at 55898 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: Maxime Devos <maximedevos <at> telenet.be>, 55898 <at> debbugs.gnu.org
Subject: Re: bug#55898: Services depending on new Shepherd features may fail
 until reboot
Date: Thu, 01 Sep 2022 09:18:01 -0400

Hi,

Ludovic Courtès <ludo <at> gnu.org> writes:

> Hi Maxim,
>
> Maxim Cournoyer <maxim.cournoyer <at> gmail.com> skribis:
>
>> Agreed, but the context differs wildly: while Autoconf or browsers for
>> example really are facing a diversity of configuration, the version of
>> Shepherd used in Guix System is known and controlled.  So the only
>> problems bound to happen are in this context:
>>
>> 1. New Shepherd version introduced in Guix (package upgrade).
>>
>> 2. New Shepherd features used by services.
>>
>> 3. Machine reconfigured using a commit including 1 and 2.
>>
>> The problems are temporary: upon a reboot the running Shepherd version
>> will be the latest, and have all the features needed.
>>
>> Hence my suggestion to use something simple to improve the user
>> experience of a user faced with 3.
>
> So are you suggesting replacing:
>
>   (defined? 'make-inetd-constructor)
>
> by something like:
>
>   (version<? shepherd-version "0.9.0")
>
> or is it something different that you have in mind?

I had something different on mind; I was thinking of some added field to
our shepherd-service object where the minimal version of Shepherd
required could be specified, e.g. "0.9.1".

The check could be abstracted in the shepherd-service implementation,
avoiding services writers to handle that by themselves in *each* service
requiring so.

The benefit would be an improved user experience, and cleaner service
code.  Upon reconfiguring a machine not yet equipped with a new enough
Shepherd, Shepherd could print:

--8<---------------cut here---------------start------------->8---
The x, y and z services won't be started until the next reboot, as they
require a newer Shepherd version.
--8<---------------cut here---------------end--------------->8---

Instead of seeing the new services fail to run without (for the end
user) without any obvious reason.

Does that make sense?

Thanks,

Maxim

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.