bug#43075: Prioritize providing substitutes for security-critical packages with potentially long build times

[Mason Hock]

On Thu Sep 10, 2020 at 1:00 AM PDT, Ludovic Courtès wrote:
> Hi,
>
> chaosmonk <chaosmonk@riseup.net> skribis:
>
> > ungoogled-chromium receives frequent security updates, so it is
> > important for users to keep it up-to-date.  However, binary
> > substitutes for the latest version are usually not available, and it
> > can take a  very long time to build from source, possibly multiple
> > days on low-end hardware.  This might tempt or force some users to put
> > off upgrading the package and run an older, vulnerable version until a
> > binary substitute is available or they have a chance to set aside the
> > uptime needed to build from source.
> >
> > I don't know what Guix's CI system looks like or how packages are
> > queued for building, but if there is a way to prioritize builds for
> > certain packages, I propose that substitutes for packages like
> > ungoogled-chromium should be built as soon as possible once there is a
> > new version.  Other security-critical packages with potentially long
> > build times that come to mind are icecat and linux-libre.
>
> Thanks for your feedback. Our build farm has often been lagging behind
> lately and that’s something we’ve been working on. The
> ungoogled-chromium package is even more problematic because it takes
> more than ~80 CPU-hours to build, and that often times out with our
> current build farm settings (where we don’t allow builds to take more
> than 6h, IIRC).

Yes, Chromium's build time is obscene.  However, not providing
substitutes for it duplicates that problem to the machines of every Guix
user who uses ungoogled-chromium.  In the time that it would take Guix's
build farm to build u-c it could probably build many other packages, but
users are in the exact same situation, so a substitute for u-c is likely
more valuable to them than substitutes for those other packages.  If it
is possible to override the 6h timeout value for individual packages, I
think that it would be worth doing so for u-c, and perhaps for Icecat
and Linux-libre as well.

> Right now we’re trying to improve build throughput in general but your
> proposal makes sense, of course.
>
> Thanks,
> Ludo’.