Building with bun2nix.writeBunApplication

writeBunApplication is provided as a library function as a convenient extension over mkDerivation. If you are looking to use writeBunApplication, please take a look over there first to familiarize yourself with its arguments.

This function is intended for use building non-compilable programs that run under bun.

Note: writeBunApplication takes heavy inspiration from pkgs.writeShellApplication. Think of it as an alternative which also manages bun dependencies.

When to use:

• If you need something like a nextjs server that needs the original source directory and a valid node_modules to run
• If you want to run a bunx binary as if it is a regular system executable with bun2nix managed dependencies.

When to avoid:

• You should avoid this at all if you can bundle your application in a way where it produces a standalone artifact. This could be something like a website, a bun binary, or anything else that doesn't care about the original source. Use the hook or the mkDerivation to build those kinds of projects instead.

Example

Currently, basic usage would look something like (to package a nextjs server):

{bun2nix, ...}:
bun2nix.writeBunApplication {
  # Could also be `pname` and `version`
  # See the `mkDerivation` docs if this
  # looks unfamiliar to you
  packageJson = ./package.json;

  src = ./.;

  # Use the `build` script from
  # `package.json` instead of
  # bun's bundler accessed via
  # `bun build`
  #
  # Confusing, isn't it?
  buildPhase = ''
    bun run build
  '';

  # Start script to use to launch
  # your project at runtime
  startScript = ''
    bun run start
  '';

  bunDeps = bun2nix.fetchBunDeps {
    bunNix = ./bun.nix;
  };
}

Or, to package an arbitrary bunx binary (as long as it's in bun.nix somewhere)

{bun2nix, ...}:
bun2nix.writeBunApplication {
  packageJson = ./package.json;

  src = ./.;

  dontUseBunBuild = true;
  dontUseBunCheck = true;

  startScript = ''
    bunx cowsay "$@"
  '';

  bunDeps = bun2nix.fetchBunDeps {
    bunNix = ./bun.nix;
  };
}

Or, to package a simple web server that uses cowsay and a runtime environment variable:

# In your default.nix
{ pkgs, bun2nix, ... }:
bun2nix.writeBunApplication {
  pname = "cowsay-server";
  version = "1.0.0";

  src = ./.;

  startScript = ''
    bun run index.ts
  '';

  runtimeInputs = [ pkgs.cowsay ];
  runtimeEnv = {
    USER = "Nix";
  };

  bunDeps = bun2nix.fetchBunDeps {
    bunNix = ./bun.nix;
  };
}

And the corresponding index.ts:

import { $ } from "bun";

const user = process.env.USER || "World";

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const message = `Hello, ${user}!`;
    const cowsay = await $`cowsay ${message}`.text();
    return new Response(cowsay);
  },
});

console.log(`Listening on http://localhost:${server.port} ...`);

Arguments

The full list of accepted arguments is:

Additionally, the full range of config options from mkDerivation is available too.