forked from lix-project/lix
5cd72598fe
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.
40 lines
1.6 KiB
Bash
40 lines
1.6 KiB
Bash
source common.sh
|
|
|
|
requireDaemonNewerThan "2.8pre20220311"
|
|
|
|
enableFeatures "ca-derivations ca-references impure-derivations"
|
|
|
|
clearStore
|
|
|
|
# Basic test of impure derivations: building one a second time should not use the previous result.
|
|
printf 0 > $TEST_ROOT/counter
|
|
|
|
json=$(nix build -L --no-link --json --file ./impure-derivations.nix impure)
|
|
path1=$(echo $json | jq -r .[].outputs.out)
|
|
path1_stuff=$(echo $json | jq -r .[].outputs.stuff)
|
|
[[ $(< $path1/n) = 0 ]]
|
|
[[ $(< $path1_stuff/bla) = 0 ]]
|
|
|
|
[[ $(nix path-info --json $path1 | jq .[].ca) =~ fixed:r:sha256: ]]
|
|
|
|
path2=$(nix build -L --no-link --json --file ./impure-derivations.nix impure | jq -r .[].outputs.out)
|
|
[[ $(< $path2/n) = 1 ]]
|
|
|
|
# Test impure derivations that depend on impure derivations.
|
|
path3=$(nix build -L --no-link --json --file ./impure-derivations.nix impureOnImpure -vvvvv | jq -r .[].outputs.out)
|
|
[[ $(< $path3/n) = X2 ]]
|
|
|
|
path4=$(nix build -L --no-link --json --file ./impure-derivations.nix impureOnImpure -vvvvv | jq -r .[].outputs.out)
|
|
[[ $(< $path4/n) = X3 ]]
|
|
|
|
# Test that (self-)references work.
|
|
[[ $(< $path4/symlink/bla) = 3 ]]
|
|
[[ $(< $path4/self/n) = X3 ]]
|
|
|
|
# Input-addressed derivations cannot depend on impure derivations directly.
|
|
nix build -L --no-link --json --file ./impure-derivations.nix inputAddressed 2>&1 | grep 'depends on impure derivation'
|
|
|
|
drvPath=$(nix eval --json --file ./impure-derivations.nix impure.drvPath | jq -r .)
|
|
[[ $(nix show-derivation $drvPath | jq ".[\"$drvPath\"].outputs.out.impure") = true ]]
|
|
[[ $(nix show-derivation $drvPath | jq ".[\"$drvPath\"].outputs.stuff.impure") = true ]]
|