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https://github.com/Profpatsch/yarn2nix

Build and deploy node packages with nix from yarn.lock files.
https://github.com/Profpatsch/yarn2nix

Last synced: 9 days ago
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Build and deploy node packages with nix from yarn.lock files.

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README 

        

ATTENTION: You are not looking at the `yarn2nix` as packaged in `nixpkgs`. This is an alternative implementation, with different tradeoffs.

For an overview of the history of these tools and current options, see [this nixpkgs issue](https://github.com/NixOS/nixpkgs/issues/20637).



I currently don’t have much time to maintain this project, it should work for some cases, but has not been “battle-tested” very much.



Alternative, more active projects:



* https://github.com/canva-public/js2nix (handles dependency cycles correctly, does not require flakes)

* https://github.com/nix-community/dream2nix (requires flakes)



# yarn2nix



```

yarn2nix [--offline] [path/to/yarn.lock]



  Convert a `yarn.lock` into a synonymous nix expression.

  If no path is given, search for `./yarn.lock`.

  If --offline is given, abort if figuring out a hash

  requires network access.



yarn2nix --template [path/to/package.json]



  Generate a package template nix-expression for your `package.json`.

```



## Features



- Purely transform `yarn.lock` files into very minimal, line-diffable nix expressions.

- Nix is used to its fullest. Every package is a derivation, whole dependency

  subtrees are shared in an optimal way, even between projects.

- The ability to resolve git dependencies by prefetching their repos and including the hashes.

- Completely local transformation if there are no git dependencies (can be used inside nix-build, no large file check-in).

- Extremely fast.

- Nice code that can be easily extended, new repositories introduced, adapt to new versions of the `yarn.lock` format.

- Comes with a [nix library][nix-lib] that uses the power of overlays to make overriding dependencies possible.

- POWERED BY [HNIX](https://github.com/haskell-nix/hnix)™ since before it was cool.



Probably a few more.



## Example Output



The [CodiMD server](https://github.com/codimd/server) is an elaborate npm package with hundreds of

dependencies. `yarn2nix` flawlessly parses the current (2020-07) `yarn.lock`

file distributed with the project, including resolving their manual git forks of

multiple npm packages:



```

$ yarn2nix ~/tmp/server/yarn.lock | wc

   7320   22701  399111

$ wc ~/tmp/server/yarn.lock

 11938  18615 500078 /home/lukas/tmp/server/yarn.lock

```



The output of this conversion [can be seen

here](https://gist.github.com/sternenseemann/0c253305350b2406e38c700b840869f2). Also

note that [git dependencies are resolved

correctly](https://gist.github.com/sternenseemann/0c253305350b2406e38c700b840869f2#file-codimd-dependencies-nix-L2086-L2087).



Pushing it through the provided [library of nix

functions][nix-lib], we get a complete build of CodiMD's

dependencies, using the project template (generated with `--template`), we also

build the CodiMD server. Included executables will be in `node_modules/.bin` as expected and

correctly link to their respective library paths in the nix store, for example:



```

$ /nix/store/zs9jk7yhdxsasn26m0903fq89cmyllzv-CodiMD-1.6.0/node_modules/.bin/markdown-it -v

10.0.0

$ readlink /nix/store/zs9jk7yhdxsasn26m0903fq89cmyllzv-CodiMD-1.6.0/node_modules/.bin/markdown-it

/nix/store/bgas2l5izznq1b61a3jyf3gpb73x8chn-markdown-it-10.0.0/bin/markdown-it.js

```



[nix-lib]: ./nix-lib/default.nix



## Building `yarn2nix`



```

$ nix-build

$ result/bin/yarn2nix

```



## Using the generated nix files to build a project



**Note:** This is a temporary interface. Ideally, the library will be in nixpkgs

and yarn2nix will be callable from inside the build (so the resulting nix files

don’t have to be checked in).



Once you have the `yarn2nix` binary, use it to generate nix files for the

`yarn.lock` file and the `package.json`:



```shell

$ yarn2nix ./jsprotect/yarn.lock > npm-deps.nix

$ yarn2nix --template ./jsproject/package.json > npm-package.nix

```



Then use the library to assemble the generated files in a `default.nix`:



```nix

let

  pkgs = import  {};

  yarn2nix = import /path/to/yarn2nix {};

  nixLib = yarn2nix.nixLib;



in

  nixLib.buildNodePackage

    ( { src = nixLib.removePrefixes [ "node_modules" ] ./.; } //

      nixLib.callTemplate ./npm-package.nix

        (nixLib.buildNodeDeps (pkgs.callPackage ./npm-deps.nix {})))

```



Finally, run `nix-build`, and voilà, in `./result/` you find the project with

all its dependencies correctly linked to their corresponding `node_modules`

folder, recursively.



## Using private package repository



Since `yarn2nix` uses standard `fetchurl` to download packages,

it is possible to authenticate by overriding `fetchurl`

to use the access credentials in `/etc/nix/netrc`.



Refer to the [Enterprise NixOS Wiki article](https://nixos.wiki/wiki/Enterprise)

for instructions.



## Development



```

$ nix-shell

nix-shell> ninja

nix-shell> cabal build yarn2nix

```