Alex Hunt
850e550422
Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/39456 **Fixes new debugger launch flow on Android:** D49158227 aimed to improve proxy-safe behaviour for remote dev servers by auto-detecting the appropriate server URL for clients using the `Host` header (etc) from the HTTP request. However, this approach broke the local case for Android emulators and externally connected devices since they would originate from a device-relative server hostname — e.g. `10.0.2.2` for the stock Android emulator. https://pxl.cl/3mVmR This commit reverts to an explicit approach where callers specify the base URL to the dev server that should be addressible from the development machine — now as a single `serverBaseUrl` option. **Changes** - Adds new `serverBaseUrl` option to `createDevMiddleware`, designed to be the base URL value for constructing dev server URLs returned in endpoints such as `/json/list`. - This changes little for the `localhost` case (now enabling `https://` URLs), but enables remote dev server setups to specify this cleanly. - Updates call site in `community-cli-plugin`. Changelog: [Internal] Reviewed By: robhogan Differential Revision: D49276125 fbshipit-source-id: 2b6a8507073649832993971aa9d0870f54c9bd44
@react-native/dev-middleware
Dev server middleware supporting core React Native development features. This package is preconfigured in all React Native projects.
Usage
Middleware can be attached to a dev server (e.g. Metro) using the createDevMiddleware API.
import { createDevMiddleware } from '@react-native/dev-middleware';
function myDevServerImpl(args) {
...
const {middleware, websocketEndpoints} = createDevMiddleware({
projectRoot: metroConfig.projectRoot,
serverBaseUrl: `http://${args.host}:${args.port}`,
logger,
});
await Metro.runServer(metroConfig, {
host: args.host,
...,
unstable_extraMiddleware: [
middleware,
// Optionally extend with additional HTTP middleware
],
websocketEndpoints: {
...websocketEndpoints,
// Optionally extend with additional WebSocket endpoints
},
});
}
Included middleware
@react-native/dev-middleware is designed for integrators such as @expo/dev-server and @react-native/community-cli-plugin. It provides a common default implementation for core React Native dev server responsibilities.
We intend to keep this to a narrow set of functionality, based around:
- Debugging — The Chrome DevTools protocol (CDP) endpoints supported by React Native, including the Inspector Proxy, which facilitates connections with multiple devices.
- Dev actions — Endpoints implementing core Dev Menu actions, e.g. reloading the app, opening the debugger frontend.
HTTP endpoints
DevMiddlewareAPI.middleware
These are exposed as a connect middleware handler, assignable to Metro.runServer or other compatible HTTP servers.
GET /json/list, /json (CDP)
Returns the list of available WebSocket targets for all connected React Native app sessions.
GET /json/version (CDP)
Returns version metadata used by Chrome DevTools.
POST /open-debugger
Open the JavaScript debugger for a given CDP target (direct Hermes debugging).
Example
curl -X POST 'http://localhost:8081/open-debugger?appId=com.meta.RNTester'
WebSocket endpoints
DevMiddlewareAPI.websocketEndpoints
/inspector/device
WebSocket handler for registering device connections.
/inspector/debug
WebSocket handler that proxies CDP messages to/from the corresponding device.
Contributing
Changes to this package can be made locally and tested against the rn-tester app, per the Contributing guide. During development, this package is automatically run from source with no build step.