perf: add option to bundle pages externals

packages/next/src/build/handle-externals.ts

@@ -372,7 +372,8 @@ export function makeExternalHandler({
         config.transpilePackages,
         resolvedExternalPackageDirs
       ) ||
-      (isEsm && isAppLayer)
+      (isEsm && isAppLayer) ||
+      (!isAppLayer && config.experimental.bundlePagesExternals)
 
     if (/node_modules[/\\].*\.[mc]?js$/.test(res)) {
       if (isWebpackServerLayer(layer)) {

packages/next/src/server/config-schema.ts

@@ -520,6 +520,9 @@ const configSchema = {
         serverSourceMaps: {
           type: 'boolean',
         },
+        bundlePagesExternals: {
+          type: 'boolean',
+        },
       },
       type: 'object',
     },

packages/next/src/server/config-shared.ts

@@ -330,6 +330,10 @@ export interface ExperimentalConfig {
    * @internal Used by the Next.js internals only.
    */
   trustHostHeader?: boolean
+  /**
+   * Enables the bundling of node_modules packages (externals) for pages server-side bundles.
+   */
+  bundlePagesExternals?: boolean
 }
 
 export type ExportPathMap = {
@@ -769,6 +773,7 @@ export const defaultConfig: NextConfig = {
     turbotrace: undefined,
     typedRoutes: false,
     instrumentationHook: false,
+    bundlePagesExternals: false,
   },
 }
 

test/integration/externals-pages-bundle/next.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  experimental: {
+    bundlePagesExternals: true,
+  },
+}

test/integration/externals-pages-bundle/pages/index.js

@@ -0,0 +1,13 @@
+import { foo } from 'external-package'
+
+export async function getServerSideProps() {
+  return {
+    props: {
+      foo,
+    },
+  }
+}
+
+export default function Index({ foo }) {
+  return <div>{foo}</div>
+}

test/integration/externals-pages-bundle/test/index.test.js

@@ -0,0 +1,18 @@
+/* eslint-env jest */
+
+import fs from 'fs-extra'
+import { join } from 'path'
+import { nextBuild } from 'next-test-utils'
+
+const appDir = join(__dirname, '../')
+
+describe('bundle pages externals with config.experimental.bundlePagesExternals', () => {
+  it('should have no externals with the config set', async () => {
+    await nextBuild(appDir, [], { stdout: true })
+    const output = await fs.readFile(
+      join(appDir, '.next/server/pages/index.js'),
+      'utf8'
+    )
+    expect(output).not.toContain('require("external-package")')
+  })
+})