Add NEXT_PRIVATE_TARGET when using old serverless

Author: ofhouse

packages/runtime/src/index.ts

@@ -262,6 +262,9 @@ export async function build({
   const nodeVersion = await getNodeVersion(entryPath, undefined, config, meta);
   const spawnOpts = getSpawnOptions(meta, nodeVersion);
 
+  const isServerTarget =
+    nextVersionRange && isServerTargetNext(nextVersionRange);
+
   // Add Vercel build environment variables that some dependencies need
   // to determine a Vercel like build environment
   spawnOpts.env = {
@@ -273,6 +276,15 @@ export async function build({
     INIT_CWD: entryPath,
   };
 
+  // Next.js changed the default output folder beginning with
+  // 10.0.8-canary.15 from `.next/serverless` to `.next/server`.
+  // This is an opt-out of this behavior for older versions.
+  // https://github.com/dealmore/terraform-aws-next-js/issues/86
+  // https://github.com/vercel/next.js/pull/22731
+  if (!isServerTarget) {
+    spawnOpts.env['NEXT_PRIVATE_TARGET'] = 'experimental-serverless-trace';
+  }
+
   const nowJsonPath = await findUp(['now.json', 'vercel.json'], {
     cwd: entryPath,
   });
@@ -351,8 +363,6 @@ export async function build({
     console.warn('WARNING: You should not upload the `.next` directory.');
   }
 
-  const isServerTarget =
-    nextVersionRange && isServerTargetNext(nextVersionRange);
   const isLegacy =
     !isServerTarget && nextVersionRange && isLegacyNext(nextVersionRange);
   debug(