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Configuration

In this section we describe the blueprint configuration options:

  • prefix: This lets you specify a directory to hold the folders other than the flake.nix location.
  • systems: Defines which systems the project should be used and deployed on.
  • nixpkgs.config: If set, Blueprint will create a new instance of nixpkgs for each system.
  • nixpkgs.overlays: If set, blueprint will create a new instance of nixpkgs for each system.

These are available by changing the flake.nix output invocation with additional parameters.

Below we provide more detail on each, along with examples.

prefix

Set this if you want to load the blueprint from a directory within the repository other than the flake location.

Default: "."

Type: string.

For example, add the following prefix line to your output invocation:

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outputs = inputs:
  inputs.blueprint {
    inherit inputs;
    prefix = "nix/";
  };

Then, you can add a nix folder inside the same folder that holds your flake file, and place all your folders within this nix folder.

Tip: Although you can choose any folder you like, we recommend the name "nix" for your folder, as this is becoming the defacto standard.

systems

Defines for which systems the project should be used and deployed on.

Default: it will load the inputs.systems flake input, first from the current flake, and then fallback to the blueprint one. (see https://github.com/nix-systems/default).

Type: list of <kernel>-<arch> strings.

Example:

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{
  outputs = inputs: inputs.blueprint {
    inherit inputs;
    systems = [ "aarch64-linux" "x86_64-linux" ];
  };
}

nixpkgs.config

If set, blueprint will create a new instance of nixpkgs for each system, with the passed config.

Default: inputs.nixpkgs.legacyPackages.<system>.

Type: attrset.

For example, the following sets the allowUnfree attribute of nixpkgs.config to true:

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{
  outputs = inputs: inputs.blueprint {
    inherit inputs;
    nixpkgs.config.allowUnfree = true;
  };
}

nixpkgs.overlays

NOTE: It's better to use perSystem composition style instead of overlays if you can.

If set, blueprint will create a new overlay with the passed config.

Type: list of functions.

Here's an example that creates a couple of overlays; the first ("otherflake") reuses an overlay defined in another flake, and the second, an inline overlay, defines an overlay that replaces the default git package with the smaller gitMinimal:

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{
  outputs = inputs: inputs.blueprint {
    inherit inputs;
    nixpkgs.overlays = [
      inputs.otherflake.overlays.default
      (final: prev: {
        git = final.gitMinimal;
      })
    ];
  };
}