nix flake check: Skip substitutable derivations#13998
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Mic92 merged 1 commit intoNixOS:masterfrom Sep 15, 2025
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Looking the binary cache download statistics for the github ASN, I would like to see this in - it saves money and time for everyone. It has been now tested for a while (and is not a very complex change) in the other two implementations. |
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Per #13574 (comment) and the following, if we can have some sort of "todo remove" in the code, then I am good with this. |
Ericson2314
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edolstra
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Since `nix flake check` doesn't produce a `result` symlink, it doesn't actually need to build/substitute derivations that are already known to have succeeded, i.e. that are substitutable. This can speed up CI jobs in cases where the derivations have already been built by other jobs. For instance, a command like nix flake check github:NixOS/hydra/aa62c7f7db31753f0cde690f8654dd1907fc0ce2 should no longer build anything because the outputs are already in cache.nixos.org. Based-on: DeterminateSystems#134 Based-on: https://gerrit.lix.systems/c/lix/+/3841 Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
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| // not actually produce the outputs. | ||
| auto missing = store->queryMissing(drvPaths); | ||
| // Only occurs if `drvPaths` contains a `DerivedPath::Opaque`, which should never happen | ||
| assert(missing.unknown.empty()); |
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This assert breaks nix flake check in certain cases, not sure why...
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@Mic92 Can you flesh out the thinking here about why it shouldn't ever happen / what it implies if it does?
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This is a rebased version of #13574 Check the previous discussion there.
Since
nix flake checkdoesn't produce aresultsymlink, it doesn't actually need to build/substitute derivations that are already known to have succeeded, i.e. that are substitutable.This can speed up CI jobs in cases where the derivations have already been built by other jobs. For instance, a command like
nix flake check github:NixOS/hydra/aa62c7f7db31753f0cde690f8654dd1907fc0ce2
should no longer build anything because the outputs are already in cache.nixos.org.
Based-on: DeterminateSystems#134
Based-on: https://gerrit.lix.systems/c/lix/+/3841
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