fmnxl/yarn2nix

Generate nix expressions from a yarn.lock file

yarn2nix

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)

Requirements

Make sure to generate the lock file with yarn >= 1.10.1

Example default.nix

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

Testing the example

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

Run tests locally

./update-yarn-nix.sh
./tests/no-import-from-derivation/update-yarn-nix.sh
./run-tests.sh

License

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