Cedric van Putten
bf7f0d57cc
Summary: At Expo, we use [Expo Tools](https://github.com/expo/vscode-expo/blob/main/src/expoDebuggers.ts) to connect the [built-in vscode-js-debug](https://github.com/microsoft/vscode-js-debug) to Hermes. Since there are a few differences in vscode vs chrome devtools, we need to enable a couple of modifications through the [`customMessageHandler` API](https://github.com/facebook/react-native/pull/43291). Unfortunately, vscode itself doesn't set the `user-agent` header when connecting to the inspector proxy. Becuase of that, we'd need a fallback to "manually" mark the debugger as being vscode ([we use this query parameter here](https://github.com/expo/vscode-expo/blob/main/src/expoDebuggers.ts#L208)). This PR supports setting the `user-agent` through `?userAgent=` when the header is not set. ## Changelog: <!-- Help reviewers and the release process by writing your own changelog entry. Pick one each for the category and type tags: [ANDROID|GENERAL|IOS|INTERNAL] [BREAKING|ADDED|CHANGED|DEPRECATED|REMOVED|FIXED|SECURITY] - Message For more details, see: https://reactnative.dev/contributing/changelogs-in-pull-requests --> [GENERAL] [ADDED] - Fallback to query parameter based `user-agent` when header is unset Pull Request resolved: https://github.com/facebook/react-native/pull/43364 Test Plan: - Install [Expo Tools](https://marketplace.visualstudio.com/items?itemName=expo.vscode-expo-tools) - Start Metro with this change. - Connect a device. - Run the vscode command `"Expo: Debug Expo app ..."` - Debugger should connect, and have it's user-agent marked as: `vscode/1.87.0 vscode-expo-tools/1.3.0` Reviewed By: huntie Differential Revision: D54804556 Pulled By: motiz88 fbshipit-source-id: 1ff558ba5350811ad042d08a713438e046759feb
@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.
GET /debugger-frontend
Subpaths of this endpoint are reserved to serve the JavaScript debugger frontend.
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.