yarn v2 support

[satishbabariya]

Error: node_modules directory is missing. Please run npm install in your project directory.

when using yarn v2 expo can't able to find node_modules folder ( due to yarn v2 dosn't use them instead it uses cache with zip)

Expo DevTools is running at http://localhost:19002
Opening DevTools in the browser... (press shift-d to disable)
Error: node_modules directory is missing. Please run `npm install` in your project directory.
Couldn't start project. Please fix the errors and restart the project.
Set EXPO_DEBUG=true in your env to view the stack trace.

[brentvatne]

@satishbabariya - anything we can do to help you add support for this in expo-cli?

[satishbabariya]

@brentvatne, I think we need to add support for yarn's PnP API.
https://next.yarnpkg.com/advanced/pnpapi
https://next.yarnpkg.com/advanced/pnpify

[brentvatne]

i personally don't have time to work on that but contributions are welcome!

[fson]

Right now Metro doesn't support the Plug'n'Play mode, which is enabled by Berry (Yarn v2) by default (at least in the current 2.0.0-rc.27 version), so the most promising path to get Berry working would be using the node-modules plugin, which creates a backwards compatible node_modules folder. The plugin is enabled by creating a .yarnrc.yml file with the following contents in the project folder:

nodeLinker: node-module

However, there seems to be a bug in Yarn 2.0.0-rc.27, which makes the yarn install command hang indefinitely in this mode:

% rm -rf node_modules 
 % yarn -v 
2.0.0-rc.27
% yarn               
➤ YN0000: ┌ Resolution step
➤ YN0002: │ babel-preset-expo@npm:8.0.0 doesn't provide @babel/core@* requested by metro-react-native-babel-preset@npm:0.56.4
➤ YN0002: │ babel-preset-expo@npm:8.0.0 doesn't provide @babel/core@^7.0.0-0 requested by @babel/plugin-proposal-decorators@npm:7.8.3
➤ YN0002: │ babel-preset-expo@npm:8.0.0 doesn't provide @babel/core@^7.0.0-0 requested by @babel/preset-env@npm:7.8.3
➤ YN0002: │ expo@npm:36.0.2 doesn't provide react-native@* requested by @unimodules/react-native-adapter@npm:5.0.0
➤ YN0002: │ expo@npm:36.0.2 doesn't provide react@* requested by react-native-view-shot@npm:3.0.2
➤ YN0002: │ expo@npm:36.0.2 doesn't provide react-native@* requested by react-native-view-shot@npm:3.0.2
➤ YN0000: └ Completed in 0.32s
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed in 1.26s
➤ YN0000: ┌ Link step
➤ YN0007: │ core-js@npm:2.6.11 must be built because it never did before or the last one failed
➤ YN0000: └ Completed in 22.57s
➤ YN0000: Done with warnings in 24.2s
➤ YN0000: ⠹ ===============================================================================
^C%                                                                                                                                       

The command hangs indefinitely and the progress bar doesn't go away until yarn is terminated with ctrl-c. On the next run it finishes, but it seems that some packages are missing:

Attempting to open the project in a web browser...
(node:15094) UnhandledPromiseRejectionWarning: Error: Cannot find module 'worker-loader'
Require stack:
- /Users/ville/Projects/expo-cli/packages/webpack-config/webpack/loaders/createWorkerLoader.js
...

[tiagob]

This works for me in my expo app

In .yarnrc.yml

nodeLinker: node-module

% yarn --version
2.1.1

Like @fson said, Plug'n'Play has issues with Metro

• Support for resolving Yarn Plug 'n Play modules facebook/metro#308
• Support for Yarn Plug 'n Play react-native-community/cli#27

[github-actions]

This issue is stale because it has been open for 60 days with no activity. If there is no activity in the next 7 days, the issue will be closed.

[alamothe]

bump

[mekwall]

No reason to bump this. It's not something Expo can fix since React Native doesn't support Yarn PnP. It is tracked in react-native-community/cli#27 and facebook/metro#308

[Nantris]

@mekwall this comment seems to suggest maybe otherwise: facebook/metro#308 (comment)

But without some more reading I can't know whether that's truly relevant. I don't think that this issue is solely about PnP support, but correct me if I'm wrong.

[Nantris]

Any movement on this? Expo has been holding us back from upgrading Yarn for years now.

[mekwall]

Any movement on this? Expo has been holding us back from upgrading Yarn for years now.

See my comment above. This is not an Expo issue. You can upgrade Yarn to v3 and use it without PnP and it will work just fine with Expo and React Native. It's documented here: https://yarnpkg.com/getting-started/migration

[byCedric]

Hi all! Expo now supports npm, yarn@1, and bun without any additional setup. yarn@2+ and pnpm requires additional setup for now:

• pnpm requires a .npmrc file, containing node-linker=hoisted (docs)
• yarn v2+ requires a .yarnrc.yml file, containing nodeLinker: node-modules (docs)

Hope this helps!