feat: stop running middleware at the origin (#125)

Author: eduardoboucas

src/build/content/server.ts

@@ -2,7 +2,7 @@ import type { NetlifyPluginOptions } from '@netlify/build'
 import glob from 'fast-glob'
 import { existsSync } from 'node:fs'
 import { cp, mkdir, readFile, readdir, readlink, symlink, writeFile } from 'node:fs/promises'
-import { join, resolve } from 'node:path'
+import { dirname, join, resolve } from 'node:path'
 import { getPrerenderManifest } from '../config.js'
 import { SERVER_HANDLER_DIR } from '../constants.js'
 
@@ -22,7 +22,18 @@ export const copyNextServerCode = async ({
 
   await Promise.all(
     paths.map(async (path: string) => {
-      await cp(join(srcDir, path), join(destDir, path), { recursive: true })
+      const destPath = join(destDir, path)
+
+      // If this is the middleware manifest file, replace it with an empty
+      // manifest to avoid running middleware again in the server handler.
+      if (path === 'server/middleware-manifest.json') {
+        await mkdir(dirname(destPath), { recursive: true })
+        await writeFile(destPath, getEmptyMiddlewareManifest())
+
+        return
+      }
+
+      await cp(join(srcDir, path), destPath, { recursive: true })
     }),
   )
 }
@@ -117,3 +128,19 @@ export const writeTagsManifest = async ({
     'utf-8',
   )
 }
+
+/**
+ * Generates an empty middleware manifest. We don't want to run middleware in
+ * the server handler, because we'll run it upstream in an edge function. So
+ * we patch the manifest to make it seem like there's no middleware configured.
+ */
+const getEmptyMiddlewareManifest = () => {
+  const manifest = {
+    sortedMiddleware: [],
+    middleware: {},
+    functions: {},
+    version: 2,
+  }
+
+  return JSON.stringify(manifest)
+}

tests/e2e/edge-middleware.test.ts

@@ -19,3 +19,15 @@ test('Runs edge middleware', async ({ page }) => {
   const h1 = page.locator('h1')
   await expect(h1).toHaveText('Other')
 })
+
+test('Does not run edge middleware at the origin', async ({ page }) => {
+  const res = await page.goto(`${ctx.url}/test/next`)
+
+  expect(await res?.headerValue('x-deno')).toBeTruthy()
+  expect(await res?.headerValue('x-node')).toBeNull()
+
+  await expect(page).toHaveTitle('Simple Next App')
+
+  const h1 = page.locator('h1')
+  await expect(h1).toHaveText('Message from middleware: hello')
+})

tests/fixtures/middleware/middleware.ts

@@ -34,6 +34,8 @@ export function middleware(request: NextRequest) {
     response = NextResponse.json({ error: 'Error' }, { status: 500 })
   }
 
+  response.headers.append('Deno' in globalThis ? 'x-deno' : 'x-node', Date.now().toString())
+
   response.headers.set('x-hello-from-middleware-res', 'hello')
   return response
 }

tests/utils/fixture.ts

@@ -13,6 +13,7 @@ import { existsSync } from 'node:fs'
 import { cp, mkdir, mkdtemp, readFile, rm, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { basename, dirname, join, parse, relative, resolve } from 'node:path'
+import { env } from 'node:process'
 import { fileURLToPath } from 'node:url'
 import { v4 } from 'uuid'
 import {
@@ -59,15 +60,22 @@ function installDependencies(cwd: string) {
 export const createFixture = async (fixture: string, ctx: FixtureTestContext) => {
   ctx.cwd = await mkdtemp(join(tmpdir(), 'netlify-next-runtime-'))
   vi.spyOn(process, 'cwd').mockReturnValue(ctx.cwd)
-  ctx.cleanup = [
-    async () => {
+
+  ctx.cleanup = []
+
+  if (env.INTEGRATION_PERSIST) {
+    console.log(
+      `💾 Fixture '${fixture}' has been persisted at '${ctx.cwd}'. To clean up automatically, run tests without the 'INTEGRATION_PERSIST' environment variable.`,
+    )
+  } else {
+    ctx.cleanup.push(async () => {
       try {
         await rm(ctx.cwd, { recursive: true, force: true })
       } catch {
         // noop
       }
-    },
-  ]
+    })
+  }
 
   try {
     const src = fileURLToPath(new URL(`../fixtures/${fixture}`, import.meta.url))