pnpm-react-native-expo-example

How to run Expo and React Native in a pnpm monorepo.

Reference

Here are notes of all the difficulties encountered:

• Expo v42 - https://github.com/pnpm/pnpm/issues/3731
• React Native v0.65 - https://github.com/pnpm/pnpm/issues/3740

Usage

Ensure watchman is installed.

pnpm i

cd packages/expo-42
npm run ios


cd packages/react-native-v65
npm run start
npm run ios

How it works?

• We replace Metro's resolver with webpack/enhanced-resolve using the resolveRequest config option.
• We patch metro to fix a jest-haste-map issue.

Performance

• enhanced-resolve is super slow, so we use the unsafeCache option and write this to disk.
• Loading the initial Metro dep graph takes a long time in large monorepos but this usually only has to be done once. I think it involves reading all files in your monorepo. I think this data is cached to node_modules/.cache/metro-custom. It would be nice to share this cache if possible across multiple mobile apps.

Upgrading existing project

1. Don't forget to apply package.json#pnpm.overrides to the root of your project. (This could also be done in the pnpmfile.js.)

2. Make sure to add the pnpmfile.js lines.

Be careful of this issue when using pnpmfiles and pnpm update after updating a pnpmfile.

Troubleshooting

Show debug messages about resolving

EXPO_RESOLVE_PROGRESS=1 npm run ios

Reset metro cache and our webpack enhanced-resolve unsafeCache.

rm -rf packages/expo/node_modules/.cache

Reset watchman file watchers.

watchman watch-del-all

ReferenceError: SHA-1 for file

cd packages/expo
pnpm why metro

# Ensure there are NO results

pnpm why @vjpr/metro

# Ensure there are results

Delete all node_modules

This can fix bad dependency issues and will also solve https://github.com/pnpm/pnpm/issues/3735

npm run delete-node-modules
pnpm i

See Github issues

https://github.com/pnpm/pnpm/issues/3731

Todo

• Maybe we don't need to patch metro, and we just patch jest-haste-map because pnpm.overrides is smarter now.

For latest RN I think the issue is fixed anyway.

• Share the metro dep graph cache across projects.