Add shared monorepo build setup

[huntie]

Summary:

NOTE: Replaces #38240

Context

RFC: Decoupling Flipper from React Native core: react-native-community/discussions-and-proposals#641

Changes

To support incoming new React Native packages around debugging (including migrating over @react-native-community/cli-plugin-metro) — which target Node.js and require a build step, this PR adds a minimal shared build setup across the react-native monorepo.

The setup is closely inspired/based on the build scripts in Jest, Metro, and React Native CLI — and is a simple set of script wrappers around Babel. These are available as build commands at the root of the repo:

• yarn build — Builds all configured packages. Functionally, this:
  • Outputs a dist/ directory with built files.
  • Rewrites package.json "exports" to update every ./src/* reference to ./dist/* (source of truth).
• scripts/build/babel-register.js — Allows running all Node.js entry points from source, similar to the current setup in facebook/metro. (Example entry point file in this PR: packages/dev-middleware/src/index.js)

Build configuration (i.e. Babel config) is shared as a set standard across the monorepo, and packages are opted-in to requiring a build, configured in scripts/build.config.js.

const buildConfig /*: BuildConfig */ = {
  // The packages to include for build and their build options
  packages: {
    'dev-middleware': {target: 'node'},
  },
};

For now, there is a single target: 'node' option — this is necessary as react-native, unlike the above other projects, is a repository with packages targeting several runtimes. We may, in future, introduce a build step for other, non-Node, packages — which may be useful for things such as auto-generated TypeScript definitions.

Differences from the Metro setup

• References (and compiles out) repo-local scripts/build/babel-register.js — removing need for an npm-published dependency.

Current integration points

• CircleCI — yarn build is added to the build_npm_package and find_and_publish_bumped_packages jobs.

New Node.js package(s) are not load bearing quite yet: There are not yet any built packages added to the dependencies of packages/react-native/, so this will be further tested in a later PR (and is actively being done in an internal commit stack).

Alternative designs

Per-package config file

Replace scripts/build/config.js with a package-defined key in in package.json, similar to Jest's publishConfig.

"buildConfig": {
  "type": "node"
},

This would be the only customisation required, with a single Babel config still standardised. Another option this might receive in future is enableTypeScriptCodgeen.

Rollup

More sophisticated build tool for Node.js, used by the React codebase (albeit within a custom script setup as well).

Lerna and Nx

• Most sophisticated setup enabling caching and optimised cloud runs.
• Probably the most likely thing we'll move towards at a later stage.

Changelog: [Internal]

Differential Revision: D47760330

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D47760330

[github-actions]

	Warnings
⚠️	🔒 package.json - Changes were made to package.json. This will require a manual import by a Facebook employee.

Generated by 🚫 dangerJS against d9f3a0e

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	8,894,554	-1
android	hermes	armeabi-v7a	7,943,106	-4
android	hermes	x86	9,292,438	-2
android	hermes	x86_64	9,193,963	-3
android	jsc	arm64-v8a	9,481,107	-1
android	jsc	armeabi-v7a	8,422,649	-1
android	jsc	x86	9,465,124	-1
android	jsc	x86_64	9,779,363	-3

Base commit: 0fb7163
Branch: main

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D47760330

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D47760330

[github-actions]

This pull request was successfully merged by @huntie in cd8f5d1.

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