[rb-general] Quick reproducible test for GNU Guix

[Ludovic Courtès]

Hi Vagrant!

Vagrant Cascadian <vagrant at reproducible-builds.org> skribis:

> I did some quick reproducibility testing running GNU Guix, and so far
> got pretty good results:
>
> Using guix (and packages) built from commit:
>
>   f83d07f7778b699d46741a5667113342f5f0a737
>
> $ guix challenge --verbose --diff=diffoscope ...
> 2,463 store items were analyzed:
>   - 2,016 (81.9%) were identical
>   - 37 (1.5%) differed
>   - 410 (16.6%) were inconclusive

Woow, nice!  There are 12+K packages now, but at least that gives us a
good overview of the story for core packages.

> The log file produced was 951MB compressed with lz4, including
> diffoscope output.

Still reading it?  ;-)

> At ~82% identical, that's not too bad. The ~17% inconclusive are likely
> substitutes that haven't yet built or failed to build on the substitute
> server, or some local builds that are not yet in guix (e.g. WIP builds
> of reprotest!!). I wonder if "guix challenge" may compare some things
> that are normally only built locally (e.g. grub.cfg or similar ?).

Yes, “guix challenge” without any arguments compares all the items in
your store, which includes file specific to your machine, like
‘grub.cfg’, the initrd, etc.

If you want to focus on packages, you can run something like:

  guix challenge $(guix package -A | cut -f1)

> I did notice that when doing multiple builds in parallel, it uses a
> different user for each build, though I don't know if that's normalized
> within the build environment container. If not, that could fix quite a
> few issues! See issues mentioning "user" at:
>
>   https://salsa.debian.org/reproducible-builds/reproducible-notes/blob/master/issues.yml

The user name in the build environment is canonicalized:

  https://git.savannah.gnu.org/cgit/guix.git/tree/nix/libstore/build.cc#n1858

> Eventually, I'd like to do more systematic test of guix packages, with
> published logs per-package, rather than whatever I happened to build on
> the system so far, but this was a quick start to help flesh out ideas
> for feature requests to "guix challenge" to make this all easier... more
> on that soon!

That’d be great!

Related to that, Christopher Baines developed a nice feature for the
Guix Data Service during and after the summit: for each Guix revision,
there’s a page showing the overall package reproducibility status based
on the info obtained from our two independent build farms.  The URL is
something like
<http://data.guix.gnu.org/revision/e7ce4ef997c3db4d47d943c3e435f395b278bc50/package-reproducibility>
(right now it’s empty for some reason, but normally it shows
identical/different/inconclusive percentages.)

Thanks,
Ludo’.