Maximilian Bosch
8cb2306138
Hydra used to support aggregate jobs that only succeeded when their constituents succeed. This is still used by e.g. nixpkgs[1]. Prior art: * https://git.lix.systems/lix-project/nix-eval-jobs/pulls/17: got ported into the CppNix implementation[2] * https://github.com/nix-community/nix-eval-jobs/pull/349: implements glob expressions for constituents - something we needed at work. This also restructures the code a bit which is what I re-used here. The globbing is not part of this patch. Essentially, the following things happen here (assuming `--constituents` is set): * Derivations with `_hydraAggregate = true;` are considered aggregates. These are not written to stdout when received by a worker, but stored until the end. * Constituents can be drv paths or strings (that must be the `attr` of another job). In that case, the derivation of the aggregate job is rewritten so that it depends on the drv of the constituent job. * At the very end the aggregate jobs are also written to stdout. Additionally, this fixes one bug, the old `hydra-eval-jobs` implementation had (and we actually hit at work): Given the leaf jobs `packages.foo` & `packages.bar`, an aggregate job `aggregate0` with _hydraAggregate = true; constituents = [ "packages.bar" "packages.foo" ]; and an aggregate job `aggregate1` with constituents = [ "aggregate0" ]; then it may happen depending on the order of evaluation that `aggregate1` depends on the old derivation of `aggregate0` (i.e. the one without rewritten constituents) and doesn't depend on `packages.foo` and `packages.bar` because it was rewritten before `aggregate0` was rewritten. This is done in here correctly, but topologically sorting the aggregate jobs before rewriting those. [1] https://github.com/NixOS/nixpkgs/blob/bba6b37c9d0898867a7d9c38a1b5b77efcfb07b9/nixos/release-combined.nix#L69 [2] https://github.com/nix-community/nix-eval-jobs/pull/340 Change-Id: I5baad5e57336b4985ef8595e903814de83eb01c1
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