Re: Indication of build failure from substitute servers?

[Ricardo Wurmus <rekado@elephly.net>]

"Jonathan Frederickson" <jonathan@terracrypt.net> writes:

> Would it make sense to have some mechanism for substitute servers to be able to provide a sort of "non-existence proof" for a given
> package? Something that the CI system could publish to indicate that its build attempt for that package failed, and that clients could use
> to optionally abort without attempting a local build?

It's something I've been wanting for the past decade.  The CI system
knows when a build has failed but when checking for substitutes there is
no endpoint to ask whether the CI build has failed.

In the past we had discussed enhancements to the substitution mechanism
(with the background of making use of information from "guix challenge")
that would allow people to have a bit more control over it.  In the
meantime we have added a way to let "guix pull" determine the latest
commit with substitutes for the derivations needed for "guix pull" ---
in the same vein we could enhance the substitution mechanism to check an
endpoint on CI and abort if the remote build has been marked as failed.

If you'd like you could think this through and come up with a minimal
set of proposed changes needed to make it work.  Then we could discuss
this here and decide which of the possibile approaches would be most
appropriate.

-- 
Ricardo