nix flake check: Skip substitutable derivations #134
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...instead of having a bunch of pass-by-reference arguments.
This is already done by Worker::run().
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.
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It looks like this is cutting about 45s off |
cole-h
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Jul 9, 2025
cole-h
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Jul 9, 2025
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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. Cherry-picked from DeterminateSystems#134
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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 <[email protected]>
getchoo
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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 <[email protected]>
getchoo
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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 <[email protected]>
getchoo
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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 <[email protected]>
Mic92
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Sep 15, 2025
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 <[email protected]>
Mic92
pushed a commit
to Mic92/nix-1
that referenced
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Sep 15, 2025
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 <[email protected]>
Mic92
pushed a commit
to Mic92/nix-1
that referenced
this pull request
Sep 15, 2025
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 <[email protected]>
Mic92
pushed a commit
to Mic92/nix-1
that referenced
this pull request
Sep 15, 2025
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 <[email protected]>
Mic92
pushed a commit
to Mic92/nix-1
that referenced
this pull request
Sep 15, 2025
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 <[email protected]>
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Motivation
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
should no longer build anything because the outputs are already in cache.nixos.org.
Includes NixOS#13420.
Context
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