Re: Guix, Hydra & Nix

[Ludovic Courtès]

Sree Harsha Totakura <address@hidden> skribis:

> From the sources, I found that build-aux/hydra/*.scm convert packages into a
> format hydra understands for building them.

Yes.  Specifically, build-aux/hydra/*.scm return a list of “jobs”, where
each job is represented as an alist with a number of compulsory items,
such as ‘derivation’ (see ‘package->alist’.)

The result of those scripts is then consumed by Hydra’s
hydra-eval-guile-jobs:

  https://github.com/NixOS/hydra/blob/master/src/script/hydra-eval-guile-jobs.in

hydra-eval-guile-jobs is itself called by hydra-evaluator, from here:

  https://github.com/NixOS/hydra/blob/master/src/lib/Hydra/Helper/AddBuilds.pm

> Hydra refuses to install without nix-store.  So Nix has to be installed as 
> well.
> I'm guessing Hydra uses nix-store command to build and retrieve store paths 
> for
> packages given to it.  Is it true?

Yes.  ‘nix-store’ is essentially a client of {guix,nix}-daemon, just
like ‘guix build’.  Hydra passes ‘nix-store’ a .drv file name, a
low-level representation of the build process; ‘nix-store’ doesn’t have
to care whether it was produced by Guix or Nix, and can’t tell the
difference.  (Similarly, ‘guix build’ can be passed a .drv produced by
Nix.)

> If so, how can hydra nix-store compile Guix packages?

Just like this.  :-)

> Also, does Hydra serve the narinfo files automatically for packages which are
> built through it?  Or does it serve those files for all packages present in 
> the
> store, even the ones present in store before Hydra was installed?

The latter, it serves everything; see:

  https://github.com/NixOS/hydra/blob/master/src/lib/Hydra/View/NARInfo.pm

> The current git master of Hydra requires current git master of Nix.  But, it
> FTBS for me.  See http://pastebin.com/3bdCUrJw and 
> http://pastebin.com/Sa0bezZc.
>  Any hints?

(Please copy logs inline.)

I ignored the Docbook issue, and used a tarball from
<http://hydra.nixos.org/job/nix/trunk/tarball/latest> to work around the
Bison issue.

HTH!

Ludo’.