document Import From Derivation (IFD) policy

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Valentin Gagarin 2022-12-05 16:24:52 +01:00
parent 5b9b93b9be
commit 53b5a47c12
2 changed files with 16 additions and 1 deletions

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@ -670,3 +670,18 @@ stdenv.mkDerivation {
...
}
```
### Import From Derivation {#ssec-import-from-derivation}
Import From Derivation (IFD) is disallowed in Nixpkgs for performance reasons:
[Hydra] evaluates the entire package set, and sequential builds during evalation would increase evaluation times to become impractical.
[Hydra]: https://github.com/NixOS/hydra
Import From Derivation can be worked around in some cases by committing generated intermediate files to version control and reading those instead.
<!-- TODO: remove the following and link to Nix manual once https://github.com/NixOS/nix/pull/7332 is merged -->
See also [NixOS Wiki: Import From Derivation].
[NixOS Wiki: Import From Derivation]: https://nixos.wiki/wiki/Import_From_Derivation

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@ -332,7 +332,7 @@ mkYarnPackage rec {
## Outside of nixpkgs {#javascript-outside-nixpkgs}
There are some other options available that can't be used inside nixpkgs. Those other options are written in Nix. Importing them in nixpkgs will require moving the source code into nixpkgs. Using [Import From Derivation](https://nixos.wiki/wiki/Import_From_Derivation) is not allowed in Hydra at present. If you are packaging something outside nixpkgs, those can be considered
There are some other options available that can't be used inside nixpkgs. Those other options are written in Nix. Importing them in nixpkgs will require moving the source code into nixpkgs. Using [Import From Derivation](#ssec-import-from-derivation) is not allowed in Hydra at present. If you are packaging something outside nixpkgs, those can be considered
### npmlock2nix {#javascript-npmlock2nix}