Nix-build a set of sets of derivations

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1

Consider

nix-build -A foo
  • If foo evaluates to a derivation, it builds that derivation
  • If foo evaluates to a set of derivations, it builds all these derivations
  • If foo evaluates to a set of set of derivations, it builds … nothing

This seems a bit unfortunate if my project consists of many derivations which I may want to build all nix-build or some nix-build -A some.of.them.

Is there a good solution to that? Can I somehow mark a set of derivations so that nix-build (or rather, nix-instantiate) recurses into it?

2

Reading the code I see that

                /* If the value of this attribute is itself a set,
                   should we recurse into it?  => Only if it has a
                   `recurseForDerivations = true' attribute. */

This special attribute does not seem to be documented in the nix manual… let’s see if it works…

Yup, seems to work. TIL! Guess this can be recagorized as a howto… :slight_smile:

3

Although this solution has the downside of confusing hydra :-/

in job ‘tests.recurseForDerivations’:
error: --- TypeError --- hydra-eval-jobs
attribute 'tests.recurseForDerivations' is a Boolean, which is not supported
4

I think recurseIntoAttrs may be closer to what you want

5

This one?

  recurseIntoAttrs =
    attrs: attrs // { recurseForDerivations = true; };

looks it’s wrapping the same concept (and I am actually not convinced it it helpful to have have the same concept available both as an attributed and a similarly named function … more cognitive load, as people need to know about the attribute and recognize what the function does when they see it. At least recurseForDerivations is documentd in the nixpkg manual…

6

Hydra doesn’t understand that, yeah. What pkgs/top-level/release.nix does is, as far as I know, convert all recurseForDerivation attributes to empty sets when generating the set of jobs which are then just ignored by Hydra. Unfortunately this nix expression is pretty convoluted and I can’t point you to the exact location where this is done on the spot.

7

Indeed. I have since used the following simpel function to make the job set hydra-friendly:

…
  removeRecurseForDerivations = nixpkgs.lib.filterAttrsRecursive (k: v: k != "recurseForDerivations");
…