[next] Add flag for experimental grouping (#11177)

Just adds a flag for experimenting

.changeset/serious-mirrors-teach.md

@@ -0,0 +1,5 @@
+---
+"@vercel/next": patch
+---
+
+[next] Add flag for experimental grouping

packages/next/src/server-build.ts

@@ -186,6 +186,10 @@ export async function serverBuild({
 }): Promise<BuildResult> {
   lambdaPages = Object.assign({}, lambdaPages, lambdaAppPaths);
 
+  const experimentalAllowBundling = Boolean(
+    process.env.NEXT_EXPERIMENTAL_FUNCTION_BUNDLING
+  );
+
   const lambdas: { [key: string]: Lambda } = {};
   const prerenders: { [key: string]: Prerender } = {};
   const lambdaPageKeys = Object.keys(lambdaPages);
@@ -883,6 +887,7 @@ export async function serverBuild({
     const pageExtensions = requiredServerFilesManifest.config?.pageExtensions;
 
     const pageLambdaGroups = await getPageLambdaGroups({
+      experimentalAllowBundling,
       entryPath: projectDir,
       config,
       functionsConfigManifest,
@@ -904,6 +909,7 @@ export async function serverBuild({
     }
 
     const appRouterLambdaGroups = await getPageLambdaGroups({
+      experimentalAllowBundling,
       entryPath: projectDir,
       config,
       functionsConfigManifest,
@@ -922,6 +928,7 @@ export async function serverBuild({
     });
 
     const appRouteHandlersLambdaGroups = await getPageLambdaGroups({
+      experimentalAllowBundling,
       entryPath: projectDir,
       config,
       functionsConfigManifest,

packages/next/src/utils.ts

@@ -804,6 +804,7 @@ export interface CreateLambdaFromPseudoLayersOptions
   layers: PseudoLayer[];
   isStreaming?: boolean;
   nextVersion?: string;
+  experimentalAllowBundling?: boolean;
 }
 
 // measured with 1, 2, 5, 10, and `os.cpus().length || 5`
@@ -815,6 +816,7 @@ export async function createLambdaFromPseudoLayers({
   layers,
   isStreaming,
   nextVersion,
+  experimentalAllowBundling,
   ...lambdaOptions
 }: CreateLambdaFromPseudoLayersOptions) {
   await createLambdaSema.acquire();
@@ -862,6 +864,7 @@ export async function createLambdaFromPseudoLayers({
       slug: 'nextjs',
       version: nextVersion,
     },
+    experimentalAllowBundling,
   });
 }
 
@@ -1502,6 +1505,7 @@ export async function getPageLambdaGroups({
   internalPages,
   pageExtensions,
   inversedAppPathManifest,
+  experimentalAllowBundling,
 }: {
   entryPath: string;
   config: Config;
@@ -1524,6 +1528,7 @@ export async function getPageLambdaGroups({
   internalPages: string[];
   pageExtensions?: string[];
   inversedAppPathManifest?: Record<string, string>;
+  experimentalAllowBundling?: boolean;
 }) {
   const groups: Array<LambdaGroup> = [];
 
@@ -1565,6 +1570,7 @@ export async function getPageLambdaGroups({
 
     let matchingGroup = groups.find(group => {
       const matches =
+        !experimentalAllowBundling &&
         group.maxDuration === opts.maxDuration &&
         group.memory === opts.memory &&
         group.isPrerenders === isPrerenderRoute &&