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path: root/tests/impure-derivations.nix
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2023-12-01Put functional tests in `tests/functional`John Ericson
I think it is bad for these reasons when `tests/` contains a mix of functional and integration tests - Concepts is harder to understand, the documentation makes a good unit vs functional vs integration distinction, but when the integration tests are just two subdirs within `tests/` this is not clear. - Source filtering in the `flake.nix` is more complex. We need to filter out some of the dirs from `tests/`, rather than simply pick the dirs we want and take all of them. This is a good sign the structure of what we are trying to do is not matching the structure of the files. With this change we have a clean: ```shell-session $ git show 'HEAD:tests' tree HEAD:tests functional/ installer/ nixos/ ``` (cherry picked from commit 68c81c737571794f7246db53fb4774e94fcf4b7e)
2022-03-31Provide default values for outputHashAlgo and outputHashModeEelco Dolstra
2022-03-31Support fixed-output derivations depending on impure derivationsEelco Dolstra
2022-03-31Add support for impure derivationsEelco Dolstra
Impure derivations are derivations that can produce a different result every time they're built. Example: stdenv.mkDerivation { name = "impure"; __impure = true; # marks this derivation as impure outputHashAlgo = "sha256"; outputHashMode = "recursive"; buildCommand = "date > $out"; }; Some important characteristics: * This requires the 'impure-derivations' experimental feature. * Impure derivations are not "cached". Thus, running "nix-build" on the example above multiple times will cause a rebuild every time. * They are implemented similar to CA derivations, i.e. the output is moved to a content-addressed path in the store. The difference is that we don't register a realisation in the Nix database. * Pure derivations are not allowed to depend on impure derivations. In the future fixed-output derivations will be allowed to depend on impure derivations, thus forming an "impurity barrier" in the dependency graph. * When sandboxing is enabled, impure derivations can access the network in the same way as fixed-output derivations. In relaxed sandboxing mode, they can access the local filesystem.