Commit 7237aa70 authored by Robert Hensing's avatar Robert Hensing
Browse files

devShellTools: Docs, fix args env

parent bde2e05c

doc/build-helpers/dev-shell-tools.chapter.md

+46 −0
Original line number Diff line number Diff line
@@ -27,3 +27,49 @@ devShellTools.valueToString (builtins.toFile "foo" "bar") 
devShellTools.valueToString false

=> ""

```



:::



## `devShellTools.unstructuredDerivationInputEnv` {#sec-devShellTools-unstructuredDerivationInputEnv}



Convert a set of derivation attributes (as would be passed to [`derivation`]) to a set of environment variables that can be used in a shell script.

This function does not support `__structuredAttrs`, but does support `passAsFile`.



:::{.example}

## `unstructuredDerivationInputEnv` usage example



```nix

devShellTools.unstructuredDerivationInputEnv {

  drvAttrs = {

    name = "foo";

    buildInputs = [ hello figlet ];

    builder = bash;

    args = [ "-c" "${./builder.sh}" ];

  };

}

=> {

  name = "foo";

  buildInputs = "/nix/store/...-hello /nix/store/...-figlet";

  builder = "/nix/store/...-bash";

}

```



Note that `args` is not included, because Nix does not added it to the builder process environment.



:::



## `devShellTools.derivationOutputEnv` {#sec-devShellTools-derivationOutputEnv}



Takes the relevant parts of a derivation and returns a set of environment variables, that would be present in the derivation.



:::{.example}

## `derivationOutputEnv` usage example



```nix

let

  pkg = hello;

in

devShellTools.derivationOutputEnv { outputList = pkg.outputs; outputMap = pkg; }

```



:::

pkgs/build-support/dev-shell-tools/default.nix

+7 −1
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ let 
  inherit (builtins) typeOf;

in

rec {

  # Docs: doc/build-helpers/dev-shell-tools.chapter.md

  # Tests: ./tests/default.nix

  # This function closely mirrors what this Nix code does:

  # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/primops.cc#L1102

  # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/eval.cc#L1981-L2036
@@ -18,6 +20,8 @@ rec { 
    else toString value;





  # Docs: doc/build-helpers/dev-shell-tools.chapter.md

  # Tests: ./tests/default.nix

  # https://github.com/NixOS/nix/blob/2.8.0/src/libstore/build/local-derivation-goal.cc#L992-L1004

  unstructuredDerivationInputEnv = { drvAttrs }:

    # FIXME: this should be `normalAttrs // passAsFileAttrs`
@@ -29,13 +33,15 @@ rec { 
        else lib.nameValuePair name str

      )

      (removeAttrs drvAttrs [

        # TODO: there may be more of these

        "args"

      ]);



  # Docs: doc/build-helpers/dev-shell-tools.chapter.md

  # Tests: ./tests/default.nix

  derivationOutputEnv = { outputList, outputMap }:

    # A mapping from output name to the nix store path where they should end up

    # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/primops.cc#L1253

    lib.genAttrs outputList (output: builtins.unsafeDiscardStringContext outputMap.${output}.outPath);





}

pkgs/build-support/dev-shell-tools/tests/default.nix

+4 −0
Original line number Diff line number Diff line
@@ -149,8 +149,12 @@ in 
        )



        ''${args:+fail "args should not be set by Nix. We don't expect it to and unstructuredDerivationInputEnv removes it."}

        if [[ "''${builder:-x}" == x ]]; then

          fail "builder should be set by Nix. We don't remove it in unstructuredDerivationInputEnv."

        fi

      '';

    } // removeAttrs drvAttrs [

      # This would break the derivation. Instead, we have a check in the derivation to make sure Nix doesn't set it.

      "args"

    ]);

}