Re: Project direction with testing changes (branches and patches)

[Christopher Baines]

Ludovic Courtès <ludo@gnu.org> writes:

> Christopher Baines <mail@cbaines.net> skribis:
>
>> So, I think I've recently switched to thinking about the problem as one
>> of testing changes, rather than just testing patches. Since both patch
>> series, and branches are used to propose changes, I think this makes
>> sense.
>>
>> In abstract, when testing a change, I would break down the problem as
>> follows:
>>
>>   - You need to work out what's affected by the change, so that you can
>>     assess the impact
>>
>>   - Once you know what's effected, you can then build those
>>     packages/system tests/... and compare the build statuses and outputs
>>     against some baseline
>>
>>   - Then there's the general UI component, ideally a first time
>>     contributor would be able to take advantage of automatic feedback
>>     about a patch they submit. There's multiple other groups of users
>>     though, like patch reviewers, and committers for example.
>
> Makes sense to me.
>
> I agree that the first problem, seeing what’s affected by a change, is
> solved, but it’s still hard to get that info.  I think we could have a
> special “skin” for the Guix Data Service to make it easier for people to
> view specifically this information.  IMO the current UI has the upside
> that it’s generic and exposes all the available information, but it has
> the downside that it’s generic and exposes all the available
> information.  :-)
>
> Or we could extend Julien’s Gitile¹ to include links from commits to
> lists of changed packages.
>
> The UI doesn’t have to be a web UI actually; we could use the Data
> Service client interface at
> <https://lists.gnu.org/archive/html/guix-devel/2021-06/msg00228.html>
> and write a new CLI, Emacs mode (similar to ‘M-x build-farm’), or
> something.
>
> ¹ https://git.lepiller.eu/gitile

Indeed, the technical side of detecting changes is solved, but I agree
that there's work needed on making that information useful.

>> I think the first two sub-problems are effectively solved. The Guix Data
>> Service is able to determine the changes between two revisions (assuming
>> it's processed them). The Guix Build Coordinator can then be used to
>> build the relevant packages/system tests, and report that information
>> back to the Guix Data Service.
>>
>> The UI part is much less certain, I've done some work with Patchwork,
>> and I do have some ideas in mind, but there's still more thinking and
>> work to do in this area.
>>
>> Before pressing on though, I think it would be good to know if this is a
>> viable direction?
>
> I think we desperately need more automation, even more than when you
> started working on this!
>
> I think a first step could be to make info from the Guix Data Service
> more readily available, as suggested above.  And from there we could
> address #2 and #3.
>
> The Patchwork instance you maintain at
> <https://patches.guix-patches.cbaines.net/project/guix-patches/list/>
> does a large part of what we want, though the UI is not my favorite I
> must say.  ;-)  I wonder if we could again make minimal changes to Mumi
> so that it includes links to the relevant bits at the Data Service.
> That’d make it more readily available.  WDYT?

I think using Patchwork or Mumi is viable, it would probably not be
great to use both in the long term. The most useful thing for me would
be to pick an approach.

Patchwork is closer in terms of features I think, since it has an API
for patch series and checks. I know mumi gained the ability to generate
mbox files for patch series now though.

I think the requirements in terms of Mumi would be to have some way of
querying for patch series to test, or at least all/recent patch
series. I suppose something could just ask for the 1st or latest series
each time there's an email to a issue, that might be the simplest
approach. Then there's the bits you describe about showing relevant
information about whatever tests take place. I guess Mumi would need an
API or some way to find out about that information, and then display
it. Maybe that could happen in the form of emails with machine+human
readable data that Mumi could interpret.

Unfortunately I don't know much about the Mumi internals. Ricardo, are
you able to comment on the feasibility and whether this direction would
make sense?

>> Currently, there's no automated testing of patches, and testing of
>> branches is limited to the information that Cuirass provides on failed
>> builds. What I'm proposing for the future is: using the Guix Data
>> Service together with the Guix Build Coordinator to analyse the effects
>> of changes, whether that be from a patch series or a branch. I realise
>> that I've already been experimenting with this, what I'm mostly
>> referring to here is moving towards this being the documented approach,
>> maintained by the project, not just me.
>
> From an administrative standpoint, I very much agree that this sort of
> infrastructure should be financially supported by the project rather
> than by an individual, and documented so we can maintain it
> collectively.  Of course that involves a bit of overhead, and sometimes
> we’re not all responsive when it comes to paperwork or sysadmin (perhaps
> these are not our preferred activities?), but still, it makes sense to
> build that collectively.
>
> That’s my take.  Thanks for the update!

That sounds promising.

I think trying to change up how branches (staging/core-updates) are
tested is a good place to start. The concrete change I'm proposing is to
use an instance of the Guix Data Service plus an instance of the Guix
Build Coordinator to do the testing and builds, rather than Cuirass on
ci.guix.gnu.org which is the current approach.

The main advantages of that would be the comparison support from the
Guix Data Service, and the build performance and reliability that the
Guix Build Coordinator brings. The main disadvantage is probably the
lack of an admin like interface similar to that of Cuirass (I think this
can be remedied in the medium term though).

This would then hopefully be a stepping stone to starting to test
patches using the same infrastructure as well.

It would be good to hear what people think, particularly the
maintainers, then I can either get on trying to make it happen, or not,
depending on the feedback. I don't particularly want to push ahead
without a strong positive opinion.

Thanks,

Chris

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