75 lines
2.3 KiB
Markdown
75 lines
2.3 KiB
Markdown
# Development Shell helpers {#chap-devShellTools}
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The `nix-shell` command has popularized the concept of transient shell environments for development or testing purposes.
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<!--
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We should try to document the product, not its development process in the Nixpkgs reference manual,
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but *something* needs to be said to provide context for this library.
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This is the most future proof sentence I could come up with while Nix itself does yet make use of this.
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Relevant is the current status of the devShell attribute "project": https://github.com/NixOS/nix/issues/7501
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-->
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However, `nix-shell` is not the only way to create such environments, and even `nix-shell` itself can indirectly benefit from this library.
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This library provides a set of functions that help create such environments.
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## `devShellTools.valueToString` {#sec-devShellTools-valueToString}
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Converts Nix values to strings in the way the [`derivation` built-in function](https://nix.dev/manual/nix/2.23/language/derivations) does.
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:::{.example}
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## `valueToString` usage examples
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```nix
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devShellTools.valueToString (builtins.toFile "foo" "bar")
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=> "/nix/store/...-foo"
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```
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```nix
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devShellTools.valueToString false
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=> ""
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```
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:::
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## `devShellTools.unstructuredDerivationInputEnv` {#sec-devShellTools-unstructuredDerivationInputEnv}
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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.
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This function does not support `__structuredAttrs`, but does support `passAsFile`.
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:::{.example}
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## `unstructuredDerivationInputEnv` usage example
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```nix
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devShellTools.unstructuredDerivationInputEnv {
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drvAttrs = {
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name = "foo";
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buildInputs = [ hello figlet ];
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builder = bash;
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args = [ "-c" "${./builder.sh}" ];
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};
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}
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=> {
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name = "foo";
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buildInputs = "/nix/store/...-hello /nix/store/...-figlet";
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builder = "/nix/store/...-bash";
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}
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```
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Note that `args` is not included, because Nix does not added it to the builder process environment.
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:::
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## `devShellTools.derivationOutputEnv` {#sec-devShellTools-derivationOutputEnv}
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Takes the relevant parts of a derivation and returns a set of environment variables, that would be present in the derivation.
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:::{.example}
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## `derivationOutputEnv` usage example
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```nix
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let
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pkg = hello;
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in
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devShellTools.derivationOutputEnv { outputList = pkg.outputs; outputMap = pkg; }
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```
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:::
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