Converts yarn.lock files into nix expression.

1. Make yarn and yarn2nix available in your shell.

     cd $GIT_REPO
     nix-env -i yarn2nix -f .
     nix-env -i yarn -f .
   

2. Go to your project dir
3. If you have not generated a yarn.lock file before, run

     yarn install
   

4. Create a yarn.nix via:

  yarn2nix > yarn.nix

5. Create a default.nix to build your application (see the example below)

For example, for the front-end of weave's microservice reference application:

  with (import <nixpkgs> {});
  with (import /home/maarten/code/nixos/yarn2nix { inherit pkgs; });
  rec {
    weave-front-end = mkYarnPackage {
      name = "weave-front-end";
      src = ./.;
      packageJson = ./package.json;
      yarnLock = ./yarn.lock;
      # NOTE: this is optional and generated dynamically if omitted
      yarnNix = ./yarn.nix;
    };
  }

note: you must modify /home/maarten/code/nixos/yarn2nix

To make this work nicely, I exposed the express server in server.js as a binary:

1. Add a bin entry to packages.json with the value server.js
2. Add #!/usr/bin/env node at the top of the file
3. chmod +x server.js

1. Run nix-build In the front-end directory. Copy the result path.
2. Create an isolated environment cd /tmp; nix-shell --pure -p bash.
3. /nix/store/some-path-to-frontend/bin/weave-demo-frontend

yarn2nix is released under the terms of the GPL-3.0 license.