fix(perf): exclude /_next/static/* from generated functions

src/build/functions/server.ts

@@ -106,6 +106,7 @@ const getHandlerFile = async (ctx: PluginContext): Promise<string> => {
 
   const templateVariables: Record<string, string> = {
     '{{useRegionalBlobs}}': ctx.useRegionalBlobs.toString(),
+    '{{excludeStaticPath}}': posixJoin(ctx.buildConfig.basePath || '', '/_next/static/*'),
   }
   // In this case it is a monorepo and we need to use a own template for it
   // as we have to change the process working directory

src/build/templates/handler-monorepo.tmpl.js

@@ -49,4 +49,9 @@ export default async function (req, context) {
 export const config = {
   path: '/*',
   preferStatic: true,
+  excludedPath: [
+    // We use `preferStatic: true` so we already won't run this on *existing* static assets,
+    // but by excluding this entire path we also avoid invoking the function just to 404.
+    '{{excludeStaticPath}}',
+  ],
 }

src/build/templates/handler.tmpl.js

@@ -43,4 +43,9 @@ export default async function handler(req, context) {
 export const config = {
   path: '/*',
   preferStatic: true,
+  excludedPath: [
+    // We use `preferStatic: true` so we already won't run this on *existing* static assets,
+    // but by excluding this entire path we also avoid invoking the function just to 404.
+    '{{excludeStaticPath}}',
+  ],
 }

tests/e2e/page-router.test.ts

@@ -1,6 +1,8 @@
 import { expect } from '@playwright/test'
 import { nextVersionSatisfies } from '../utils/next-version-helpers.mjs'
 import { test } from '../utils/playwright-helpers.js'
+import { join } from 'node:path'
+import { readdir } from 'node:fs/promises'
 
 export function waitFor(millis: number) {
   return new Promise((resolve) => setTimeout(resolve, millis))
@@ -614,6 +616,34 @@ test.describe('Simple Page Router (no basePath, no i18n)', () => {
       /(s-maxage|max-age)/,
     )
   })
+
+  test.describe('static assets and function invocations', () => {
+    test('should return 200 for an existing static asset without invoking a function', async ({
+      page,
+      pageRouter,
+    }) => {
+      // Since assets are hashed, we can't hardcode anything here. Find something to fetch.
+      const [staticAsset] = await readdir(
+        join(pageRouter.isolatedFixtureRoot, '.next', 'static', 'chunks'),
+      )
+      expect(staticAsset).toBeDefined()
+
+      const response = await page.goto(`${pageRouter.url}/_next/static/chunks/${staticAsset}`)
+
+      expect(response?.status()).toBe(200)
+      expect(response?.headers()).not.toHaveProperty('x-nf-function-type')
+    })
+
+    test('should return 404 for a nonexistent static asset without invoking a function', async ({
+      page,
+      pageRouter,
+    }) => {
+      const response = await page.goto(`${pageRouter.url}/_next/static/stale123abcdef.js`)
+
+      expect(response?.status()).toBe(404)
+      expect(response?.headers()).not.toHaveProperty('x-nf-function-type')
+    })
+  })
 })
 
 test.describe('Page Router with basePath and i18n', () => {
@@ -1352,13 +1382,15 @@ test.describe('Page Router with basePath and i18n', () => {
 
   test('requesting a non existing page route that needs to be fetched from the blob store like 404.html', async ({
     page,
-    pageRouter,
+    pageRouterBasePathI18n,
   }) => {
-    const response = await page.goto(new URL('non-existing', pageRouter.url).href)
+    const response = await page.goto(
+      new URL('base/path/non-existing', pageRouterBasePathI18n.url).href,
+    )
     const headers = response?.headers() || {}
     expect(response?.status()).toBe(404)
 
-    expect(await page.textContent('p')).toBe('Custom 404 page')
+    expect(await page.textContent('p')).toBe('Custom 404 page for locale: en')
 
     // https://github.com/vercel/next.js/pull/69802 made changes to returned cache-control header,
     // after that 404 pages would have `private` directive, before that it would not
@@ -1375,13 +1407,15 @@ test.describe('Page Router with basePath and i18n', () => {
 
   test('requesting a non existing page route that needs to be fetched from the blob store like 404.html (notFound: true)', async ({
     page,
-    pageRouter,
+    pageRouterBasePathI18n,
   }) => {
-    const response = await page.goto(new URL('static/not-found', pageRouter.url).href)
+    const response = await page.goto(
+      new URL('base/path/static/not-found', pageRouterBasePathI18n.url).href,
+    )
     const headers = response?.headers() || {}
     expect(response?.status()).toBe(404)
 
-    expect(await page.textContent('p')).toBe('Custom 404 page')
+    expect(await page.textContent('p')).toBe('Custom 404 page for locale: en')
 
     expect(headers['debug-netlify-cdn-cache-control']).toBe(
       nextVersionSatisfies('>=15.0.0-canary.187')
@@ -1390,4 +1424,36 @@ test.describe('Page Router with basePath and i18n', () => {
     )
     expect(headers['cache-control']).toBe('public,max-age=0,must-revalidate')
   })
+
+  test.describe('static assets and function invocations', () => {
+    test('should return 200 for an existing static asset without invoking a function', async ({
+      page,
+      pageRouterBasePathI18n,
+    }) => {
+      // Since assets are hashed, we can't hardcode anything here. Find something to fetch.
+      const [staticAsset] = await readdir(
+        join(pageRouterBasePathI18n.isolatedFixtureRoot, '.next', 'static', 'chunks'),
+      )
+      expect(staticAsset).toBeDefined()
+
+      const response = await page.goto(
+        `${pageRouterBasePathI18n.url}/base/path/_next/static/chunks/${staticAsset}`,
+      )
+
+      expect(response?.status()).toBe(200)
+      expect(response?.headers()).not.toHaveProperty('x-nf-function-type')
+    })
+
+    test('should return 404 for a nonexistent static asset without invoking a function', async ({
+      page,
+      pageRouterBasePathI18n,
+    }) => {
+      const response = await page.goto(
+        `${pageRouterBasePathI18n.url}/base/path/_next/static/stale123abcdef.js`,
+      )
+
+      expect(response?.status()).toBe(404)
+      expect(response?.headers()).not.toHaveProperty('x-nf-function-type')
+    })
+  })
 })

tests/utils/create-e2e-fixture.ts

@@ -21,6 +21,7 @@ export interface DeployResult {
   deployID: string
   url: string
   logs: string
+  isolatedFixtureRoot: string
 }
 
 type PackageManager = 'npm' | 'pnpm' | 'yarn' | 'bun' | 'berry'
@@ -92,6 +93,7 @@ export const createE2EFixture = async (fixture: string, config: E2EConfig = {})
       cleanup: _cleanup,
       deployID: result.deployID,
       url: result.url,
+      isolatedFixtureRoot: result.isolatedFixtureRoot,
     }
   } catch (error) {
     await _cleanup(true)
@@ -292,6 +294,7 @@ async function deploySite(
     url: `https://${deployID}--${siteName}.netlify.app`,
     deployID,
     logs: output,
+    isolatedFixtureRoot,
   }
 }
 

tests/utils/playwright-helpers.ts

@@ -98,7 +98,7 @@ export const test = base.extend<
         if (response.url().includes('/_next/static/')) {
           expect(
             response.headers()['cache-control'],
-            '_next/static assets should have immutable cache control',
+            `_next/static asset (${response.url()}) should have immutable cache control`,
           ).toContain('public,max-age=31536000,immutable')
         }
       })