[SOLVED] Packaging a Node.js App with relative import

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1

Hello! I’m trying to package a fastify server using node2nix. I’m following this article’s Node2Nix section for reference.
Here’s my project flake:

{...}: {
  imports = [
    ./nix/docker.nix
  ];
  config = {
    perSystem = {
      system,
      pkgs,
      ...
    }: let
      nodejs = pkgs.nodejs-18_x;
      node2nixOutput = import ./nix {inherit system nodejs pkgs;};
      nodeDeps = node2nixOutput.nodeDependencies;
    in {
      packages = {
        marco = pkgs.stdenv.mkDerivation {
          name = "marco";
          src = ./.;
          propagatedBuildInputs = [nodejs];
          buildPhase = ''
            runHook preBuild
            # this line removes a bug where value of $HOME is set to a non-writable /homeless-shelter dir
            export HOME=$(pwd)
            # symlink the generated node deps to the current directory for building
            ln -sf ${nodeDeps}/lib/node_modules ./node_modules
            export PATH="${nodeDeps}/bin:$PATH"
            npm run build
            runHook postBuild
          '';
          installPhase = ''
            runHook preInstall
            # Note: you need some sort of `mkdir` on $out for any of the following commands to work
            mkdir -p $out/bin
            # copy only whats needed for running the built app
            cp package.json $out/package.json
            cp -r dist $out/dist
            ln -sf ${nodeDeps}/lib/node_modules $out/node_modules

            # copy entry point, in this case our index.ts has the node shebang
            # nix will patch the shebang to be the node version specified in buildInputs
            # you could also copy in a script that is basically `npm run start`
            cp -r dist/index.js $out/bin/marco
            chmod a+x $out/bin/marco
            runHook postInstall
          '';
        };
      };
    };
  };
}

#!/usr/bin/env node
import fastify from 'fastify';

# relative import causes error without this the built instance runs fine
import DbPlugin from './plugins/db';

const server = fastify();

server.register(DbPlugin);

server.get('/ping', async (request, reply) => {
    return 'pong\n';
});

server.listen({ host: '0.0.0.0', port: 8080 }, (err, address) => {
    if (err) {
        console.error(err);
        process.exit(1);
    }
    console.log(`Server listening at ${address}`);
});

Error I get when running nix run .#marco

Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/nix/store/f2wvbx0jzng243w5izm8lqslkh03aa6g-marco/bin/plugins/db

I also tried copying the whole dist folder to bin on installPhase, but then I’m met with:
error: unable to execute '/nix/store/r98aw9b513k2giah846spg0kwiafcag3-marco/bin/marco': Permission denied

2

The Issue is solved. I just copied the contents of the dist to bin AND created an executable from dist/index.js in installPhase.