turbopack: pass dev server address to router

packages/next-swc/crates/next-core/js/src/entry/router.ts

@@ -3,7 +3,7 @@ import type { IncomingMessage, ServerResponse } from "node:http";
 import { Buffer } from "node:buffer";
 import { createServer, makeRequest } from "@vercel/turbopack-next/ipc/server";
 import { toPairs } from "@vercel/turbopack-next/internal/headers";
-import { makeResolver, RouteResult } from "next/dist/server/lib/route-resolver";
+import { makeResolver, RouteResult, ServerAddress } from "next/dist/server/lib/route-resolver";
 import loadConfig from "next/dist/server/config";
 import { PHASE_DEVELOPMENT_SERVER } from "next/dist/shared/lib/constants";
 
@@ -52,7 +52,8 @@ let resolveRouteMemo: Promise<
 >;
 
 async function getResolveRoute(
-  dir: string
+  dir: string,
+  serverAddr: Partial<ServerAddress>
 ): ReturnType<
   typeof import("next/dist/server/lib/route-resolver").makeResolver
 > {
@@ -63,20 +64,22 @@ async function getResolveRoute(
     undefined,
     true
   );
-
-  return await makeResolver(dir, nextConfig, {
+  const middlewareCfg = {
     files: middlewareChunkGroup.filter((f) => /\.[mc]?js$/.test(f)),
     matcher: middlewareConfig.matcher,
-  });
+  }
+
+  return await makeResolver(dir, nextConfig, middlewareCfg, serverAddr);
 }
 
 export default async function route(
   ipc: Ipc<RouterRequest, IpcOutgoingMessage>,
   routerRequest: RouterRequest,
-  dir: string
+  dir: string,
+  serverAddr: Partial<ServerAddress>
 ) {
   const [resolveRoute, server] = await Promise.all([
-    (resolveRouteMemo ??= getResolveRoute(dir)),
+    (resolveRouteMemo ??= getResolveRoute(dir, serverAddr)),
     createServer(),
   ]);
 

packages/next-swc/crates/next-core/src/router.rs

@@ -385,6 +385,7 @@ async fn route_internal(
     let Some(dir) = to_sys_path(project_path).await? else {
         bail!("Next.js requires a disk path to check for valid routes");
     };
+    let server_addr = server_addr.await?;
     let result = evaluate(
         router_asset,
         project_path,
@@ -396,6 +397,10 @@ async fn route_internal(
         vec![
             JsonValueVc::cell(request),
             JsonValueVc::cell(dir.to_string_lossy().into()),
+            JsonValueVc::cell(json!({
+                "hostname": server_addr.ip(),
+                "port": server_addr.port(),
+            })),
         ],
         CompletionsVc::all(vec![next_config_changed, routes_changed]),
         /* debug */ false,

packages/next-swc/crates/next-dev-tests/tests/integration/next/router/middleware-api-fetch/input/middleware.ts

@@ -0,0 +1,13 @@
+import { NextResponse } from 'next/server'
+import type { NextRequest } from 'next/server'
+
+export async function middleware(req: NextRequest) {
+  const origin = new URL(req.url).origin;
+  const res = await fetch(`${origin}/api/endpoint`);
+  const json = await res.json();
+  return NextResponse.json(json);
+}
+
+export const config = {
+  matcher: '/fetch-endpoint',
+}

packages/next-swc/crates/next-dev-tests/tests/integration/next/router/middleware-api-fetch/input/next.config.js

@@ -0,0 +1,2 @@
+/** @type {import('next').NextConfig} */
+module.exports = {}

packages/next-swc/crates/next-dev-tests/tests/integration/next/router/middleware-api-fetch/input/pages/api/endpoint.js

@@ -0,0 +1,3 @@
+export default function handler(_req, res) {
+  res.status(200).json({ name: 'John Doe' })
+}

packages/next-swc/crates/next-dev-tests/tests/integration/next/router/middleware-api-fetch/input/pages/index.js

@@ -0,0 +1,18 @@
+import { useEffect } from 'react'
+
+export default function Foo() {
+  useEffect(() => {
+    // Only run on client
+    import('@turbo/pack-test-harness').then(runTests)
+  })
+
+  return 'index'
+}
+
+function runTests() {
+  it('should include custom env fields in middleware process', async () => {
+    const res = await fetch('/fetch-endpoint')
+    const env = await res.json()
+    expect(env).toHaveProperty('name', 'John Doe')
+  })
+}

packages/next/src/server/lib/route-resolver.ts

@@ -20,11 +20,16 @@ import {
 } from '../../shared/lib/constants'
 import type { BaseNextRequest } from '../base-http'
 
-type MiddlewareConfig = {
+export type MiddlewareConfig = {
   matcher: string[]
   files: string[]
 }
 
+export type ServerAddress = {
+  hostname: string
+  port: number
+}
+
 export type RouteResult =
   | {
       type: 'rewrite'
@@ -78,7 +83,8 @@ class DevRouteMatcherManager extends DefaultRouteMatcherManager {
 export async function makeResolver(
   dir: string,
   nextConfig: NextConfig,
-  middleware: MiddlewareConfig
+  middleware: MiddlewareConfig,
+  serverAddr: Partial<ServerAddress>
 ) {
   const url = require('url') as typeof import('url')
   const { default: Router } = require('../router') as typeof import('../router')
@@ -126,8 +132,8 @@ export async function makeResolver(
   const devServer = new TurbopackDevServerProxy({
     dir,
     conf: nextConfig,
-    hostname: 'localhost',
-    port: 3000,
+    hostname: serverAddr.hostname || 'localhost',
+    port: serverAddr.port || 3000,
   })
 
   await devServer.matchers.reload()