Re: Bringing substitutes from the Guix Build Coordinator to users

[Christopher Baines]

Christopher Baines <mail@cbaines.net> writes:

> Andreas Enge <andreas@enge.fr> writes:
>
>> Hello Chris,
>>
>> Am Sat, May 01, 2021 at 07:56:05PM +0100 schrieb Christopher Baines:
>>> I think there are some benefits for using the Guix Build Coordinator to
>>> build things for substitutes, and it would be good to work out how to
>>> get those benefits to users of Guix generally.
>>
>> my question is a bit tangential, but how can we get the substitutes that
>> the build coordinator puts on bayfront? I still have bayfront.guix.info
>> in my list of substitute servers, but does it use the same signing key
>> as before? It would be nice to document what a user should do. In my
>> opinion, a second build farm would be a useful thing, in case one server
>> goes down, or needs to be updated, for instance. (And then it allows for
>> reproducibility checks.)
>
> So, bayfront is currently serving substitutes build through the Guix
> Build Coordinator, the signing key is the same as it was before.
>
> It's only been building things at pace since yesterday though, so it'll
> be a few days at least until it's caught up.
>
> I agree that having multiple independent substitute providers would be
> nice, and getting bayfront working well is a step towards that.

Continuing on the subject of bayfront, it seems like the most feasible
way to get substitutes build through the Guix Build Coordinator to users
might be through it. At least there hasn't been any other leads yet from
this thread.

Luckily, from a thread ("Machine things") on guix-sysadmin [1] a number
of months ago, the suggestion of using the Guix Build Coordinator on
bayfront already came up, so it's actually been running for around a
month, and making progress building things for part of that.

1: https://lists.gnu.org/mailman/private/guix-sysadmin/2021-February/003412.html

Getting some benefit from the substitutes will require a few things
though, firstly getting things in order such that a good proportion and
range of substitutes are available, and secondly amending the default
configuration to include bayfront.

On the default configuration point, what are the prerequsites for that?
Beyond having some substitutes to offer, is there any particular
criteria to consider, perhaps about the machines involved?

On the subject of the machines involved, currently there's:

 - x86_64-linux + i686-linux
   - bayfront (coordinator, agent and serving substitutes)
   - harbourfront
   - milano-guix-1
 - aarch64-linux + armhf-linux
   - monokuma

I'd like to get some childhurd VMs running, they can go on the x86_64
machines, and hopefully there will be enough resources to keep up with
x86_64-linux, i686-linux, while doing some i586-gnu builds. If I have
some luck, I might also be able to get some powerpc64 hardware, and I do
have two Raspberry Pi 4's, but they're not running Guix as the OS yet,
so it would be good to work out if they're suitable, or better left to
other tasks.

There's a few intertangled things, but the main question is, if bayfront
can be a source of substitutes, what's the path to actually have that
benefit users?

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