Allow node cluster mode as default

package.json

@@ -5,8 +5,9 @@
 	"license": "MIT",
 	"scripts": {
 		"dev": "tsx --watch ./example/index.ts",
-		"test": "bun run test:node",
+		"test": "bun run test:node && bun run test:node-cluster",
 		"test:node": "npm install --prefix ./test/node/cjs/ && npm install --prefix ./test/node/esm/ && node ./test/node/cjs/index.js && node ./test/node/esm/index.js",
+		"test:node-cluster": "node ./test/cluster/cluster.cjs port && node ./test/cluster/cluster.cjs object && node ./test/cluster/cluster.cjs true && node ./test/cluster/cluster.cjs false",
 		"build": "bun build.ts",
 		"release": "npm run build && npm run test && npm publish --access public"
 	},

src/index.ts

@@ -107,9 +107,11 @@ export const node = () => {
 								port: options,
 								silent: true,
 								websocket,
-								fetch: app.fetch
+								fetch: app.fetch,
+								reusePort: true
 							}
 						: {
+								reusePort: true,
 								...options,
 								silent: true,
 								websocket,

test/cluster/cluster.cjs

@@ -0,0 +1,89 @@
+const cluster = require('node:cluster')
+const { Elysia } = require('elysia')
+const { exit, pid } = require('node:process')
+const { node } = require('@elysiajs/node')
+
+const workersAmount = 5
+const port = 3000
+// Use args to differentiate parameter
+// So code is more compact
+const arg2 = process.argv[2]
+let parameter
+if (arg2 === 'port') {
+	parameter = port
+} else if (arg2 === 'object') {
+	parameter = {
+		port
+	}
+} else if (arg2 === 'true') {
+	parameter = {
+		port,
+		reusePort: true
+	}
+} else if (arg2 === 'false') {
+	parameter = {
+		port,
+		reusePort: false
+	}
+} else {
+	console.error(`Unknown argument: ${arg2}. Expected: port, object, true, false`)
+	exit(1)
+}
+
+/**
+ * Method to stop workers and then exit the current program 
+ * @param {Worker[]} workers list of workers
+ * @param {number} code exit code
+ */
+function shutdown(workers, code) {
+	workers.forEach((it) => {
+		it.kill()
+	})
+	exit(code)
+}
+
+/**
+ * Start primary node
+ * This will create workers and then send request to primary which will then
+ * spread the requests to the workers. After that it will check for the result.
+ */
+async function startPrimary() {
+	let workers = []
+	for (let i = 0; i < workersAmount; i++) {
+		workers.push(cluster.fork())
+	}
+	// we need some delay to allow Elysia to initialize
+	await new Promise((resolve) => setTimeout(resolve, 2000))
+
+	// Make n API calls, we should receive n different PIDs back
+	// Checking if a server is run can only be done this way at the moment
+	// because error is really deep in srvx and async
+	// Even callback in Elysia.listen will be still be run even on error
+	const promises = workers.map(async (it) => {
+		const result = await fetch(`http://localhost:${port}`)
+		const workerPid = await result.text()
+		return workerPid
+	})
+	const result = await Promise.all(promises)
+	const pidsCount = new Set(result).size;
+	if (arg2 === 'false') {
+		if (pidsCount !== 1) {
+			console.error('❌ Server should return 1 pid.')
+			shutdown(workers, 1)
+		}
+		console.log('✅ Test exclusive mode succeed!')
+		shutdown(workers, 0)
+	}
+	if (pidsCount !== workersAmount) {
+		console.error("❌ Clustering error, number of pids doesn't match.")
+		shutdown(workers, 1)
+	}
+	console.log('✅ Test cluster mode succeed!')
+	shutdown(workers, 0)
+}
+
+if (cluster.isPrimary) {
+	startPrimary()
+} else {
+	new Elysia({ adapter: node() }).get(`/`, pid).listen(parameter)
+}