In a pre-existing flake

To install bun2nix in an already existing bun project with a flake.nix, the following steps are recommended:

1. Source the bun2nix repo

Add the bun2nix flake to your inputs as follows:

bun2nix.url = "github:baileyluTCD/bun2nix";
bun2nix.inputs.nixpkgs.follows = "nixpkgs";

1.5. (Optional) Use the binary cache

The bun2nix executable typically takes a while to compile, which is typical for many rust programs, hence, because of the garnix based CI/CD, a convenient binary cache is provided.

To add it include the following in your flake.nix.

nixConfig = {
    extra-substituters = [
      "https://cache.nixos.org"
      "https://cache.garnix.io"
    ];
    extra-trusted-public-keys = [
      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
      "cache.garnix.io:CTFPyKSLcx5RMJKfLo5EEPUObbA78b0YQ2DTCJXqr9g="
    ];
};

2. Add the binary to your environment

Next, add the bun2nix program into your developer environment by adding it to your devshell.

devShells.default = pkgs.mkShell {
  packages = with pkgs; [
    bun
    bun2nix.packages.${system}.default
  ];
};

NOTE: the system variable can be gotten in a variety of convenient ways - including flake-utils or nix-systems.

3. Use the binary in a bun `postinstall` script

To keep the generated bun.nix file produced by bun2nix up to date, add bun2nix as a postinstall script to run it after every bun operation that modifies the packages in some way.

Add the following to package.json:

"scripts": {
    "postinstall": "bun2nix -o bun.nix"
}

4. Build your package with nix

Finally, a convenient package builder is exposed inside bun2nix - mkBunDerivation.

Add the following to flake.nix:

my-package = pkgs.callPackage ./default.nix {
    inherit (bun2nix.lib.${system}) mkBunDerivation;
};

And place this in a file called default.nix

{ mkBunDerivation, ... }:
mkBunDerivation {
  pname = "bun2nix-example";
  version = "1.0.0";

  src = ./.;

  bunNix = ./bun.nix;

  index = "index.ts";
}

A list of available options for mkBunDerivation can be seen at the building packages page.

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