cli: add experimental warning for auth entry point build

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/large-tables-wonder.md

@@ -2,4 +2,4 @@
 '@backstage/cli': patch
 ---
 
-Add support for optional `auth` app entry point.
+Add experimental support for optional `auth` app entry point.

packages/cli/src/lib/bundler/bundle.ts

@@ -66,6 +66,11 @@ export async function buildBundle(options: BuildOptions) {
     dist: 'dist/auth',
   });
   if (authPaths) {
+    console.log(
+      chalk.yellow(
+        `⚠️  WARNING: The app /auth entry point is an experimental feature that may receive immediate breaking changes.`,
+      ),
+    );
     configs.push(
       await createConfig(authPaths, {
         ...commonConfigOptions,

packages/cli/src/lib/bundler/server.ts

@@ -207,6 +207,13 @@ DEPRECATION WARNING: React Router Beta is deprecated and support for it will be
       entry: 'src/auth',
       dist: 'dist/auth',
     });
+    if (authPaths) {
+      console.log(
+        chalk.yellow(
+          `⚠️  WARNING: The app /auth entry point is an experimental feature that may receive immediate breaking changes.`,
+        ),
+      );
+    }
     const compiler = authPaths
       ? webpack([
           config,