look at middleware manifest to check if middleware exists

Author: mathu97

packages/@apphosting/adapter-nextjs/src/constants.ts

@@ -1,9 +1,11 @@
 import type {
   PHASE_PRODUCTION_BUILD as NEXT_PHASE_PRODUCTION_BUILD,
   ROUTES_MANIFEST as NEXT_ROUTES_MANIFEST,
+  MIDDLEWARE_MANIFEST as NEXT_MIDDLEWARE_MANIFEST,
 } from "next/constants.js";
 
 // export next/constants ourselves so we don't have to dynamically import them
 // also this gives us a better heads up if the NextJS API changes
 export const PHASE_PRODUCTION_BUILD: typeof NEXT_PHASE_PRODUCTION_BUILD = "phase-production-build";
 export const ROUTES_MANIFEST: typeof NEXT_ROUTES_MANIFEST = "routes-manifest.json";
+export const MIDDLEWARE_MANIFEST: typeof NEXT_MIDDLEWARE_MANIFEST = "middleware-manifest.json";

packages/@apphosting/adapter-nextjs/src/overrides.ts

@@ -1,11 +1,13 @@
+import { MiddlewareManifest } from "next/dist/build/webpack/plugins/middleware-plugin.js";
 import { AdapterMetadata } from "./interfaces.js";
-import { loadRouteManifest, writeRouteManifest, middlewareExists } from "./utils.js";
+import { loadRouteManifest, writeRouteManifest, loadMiddlewareManifest } from "./utils.js";
 
 export async function addRouteOverrides(
   appPath: string,
   distDir: string,
   adapterMetadata: AdapterMetadata,
 ) {
+  const middlewareManifest = await loadMiddlewareManifest(appPath, distDir);
   const routeManifest = await loadRouteManifest(appPath, distDir);
   routeManifest.headers.push({
     source: "/:path*",
@@ -14,7 +16,7 @@ export async function addRouteOverrides(
         key: "x-fah-adapter",
         value: `nextjs-${adapterMetadata.adapterVersion}`,
       },
-      ...(middlewareExists(appPath, distDir)
+      ...(middlewareExists(middlewareManifest)
         ? [
             {
               key: "x-fah-middleware",
@@ -28,3 +30,7 @@ export async function addRouteOverrides(
 
   await writeRouteManifest(appPath, distDir, routeManifest);
 }
+
+function middlewareExists(middlewareManifest: MiddlewareManifest) {
+  return Object.keys(middlewareManifest.middleware).length > 0;
+}

packages/@apphosting/adapter-nextjs/src/utils.ts

@@ -9,6 +9,8 @@ import { OutputBundleOptions, RoutesManifest } from "./interfaces.js";
 import { NextConfigComplete } from "next/dist/server/config-shared.js";
 import { OutputBundleConfig } from "@apphosting/common";
 import { AdapterMetadata } from "./interfaces.js";
+import { MiddlewareManifest } from "next/dist/build/webpack/plugins/middleware-plugin.js";
+import { MIDDLEWARE_MANIFEST } from "next/constants.js";
 
 // fs-extra is CJS, readJson can't be imported using shorthand
 export const { move, exists, writeFile, readJson, readdir, readFileSync, existsSync, mkdir } =
@@ -43,6 +45,15 @@ export async function loadRouteManifest(
   return JSON.parse(json) as RoutesManifest;
 }
 
+export async function loadMiddlewareManifest(
+  standalonePath: string,
+  distDir: string,
+): Promise<MiddlewareManifest> {
+  const manifestPath = join(standalonePath, distDir, MIDDLEWARE_MANIFEST);
+  const json = readFileSync(manifestPath, "utf-8");
+  return JSON.parse(json) as MiddlewareManifest;
+}
+
 export async function writeRouteManifest(
   standalonePath: string,
   distDir: string,
@@ -52,11 +63,6 @@ export async function writeRouteManifest(
   await writeFile(manifestPath, JSON.stringify(customManifest));
 }
 
-export function middlewareExists(standalonePathDir: string, distdir: string): boolean {
-  const middlwarePath = join(standalonePathDir, distdir, "server/middleware.js");
-  return existsSync(middlwarePath);
-}
-
 export const isMain = (meta: ImportMeta): boolean => {
   if (!meta) return false;
   if (!process.argv[1]) return false;