Redesign the dev server, decouple with Modern.js server

[chenjiahan]

Rsbuild should avoid depending on Modern.js packages, so we need to design a new dev server for Rsbuild, and allow Modern.js to replace the builtin dev server.

[9aoy]

The goal of Rsbuild Server is to be lightweight, simple, and easy to expand:

• Provide dev/preview capability for rsbuild application
• Meet the general configuration capabilities used when starting an application (such as setMiddleware, hmrClient, historyApiFallback,etc).
• Support the expansion of server capabilities to meet the complex needs of upper-level frameworks (such as modern.js) for servers

Detail Design

Rsbuild Server uses a minimalist combination of http + connect , with all built-in/extended logic added via middleware.

var connect = require('connect');
var http = require('http');

var app = connect();

app.use(function (req, res, next) {
  // req is the Node.js http request object
  // res is the Node.js http response object
  // next is a function to call to invoke the next middleware
})

//create node.js http server and listen on port
http.createServer(app).listen(3000);

devServers comparison:

	Rsbuild DevServer	Modern.js DevServer (old)	webpack-dev-server
Middleware mode	connect	modern.js custom	express
Relationship with prodServer	Shared Middleware	DevServer inherits prodServer	No prodServer
depends on route.json	❌	✔️ (depends on route.json and routing Middleware)	❌
support custom middlewares	✔️	✔️	✔️
support custom plugins	❌	✔️	❌
support static directories	❌	✔️	✔️
ssr support	❌	✔️	❌
proxy support	✔️	✔️	✔️

Breaking changes

Compared to modern.js builder, breaking changes include:

• Only match file based on static file paths. For example, if you want to access the page through /, you need to ensure that the html output path is dist/index.html
• SPA and multi-entry SPA are not supported by default, this can be achieved by configuring tools.devServer.historyApiFallback
• tools.devServer.before/after configuration is not supported, you can use tools.devServer.setupMiddlewares instead