cli: add optional auth entry point for apps

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

.changeset/large-tables-wonder.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Add support for optional `auth` app entry point.

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

@@ -127,6 +127,8 @@ export async function createConfig(
 
   plugins.push(
     new HtmlWebpackPlugin({
+      chunks: ['main'],
+      filename: 'index.html',
       template: paths.targetHtml,
       templateParameters: {
         publicPath,
@@ -135,6 +137,20 @@ export async function createConfig(
     }),
   );
 
+  if (paths.targetAuthEntry) {
+    plugins.push(
+      new HtmlWebpackPlugin({
+        chunks: ['auth'],
+        filename: 'auth/index.html',
+        template: paths.targetHtml,
+        templateParameters: {
+          publicPath,
+          config: frontendConfig,
+        },
+      }),
+    );
+  }
+
   const buildInfo = await readBuildInfo();
   plugins.push(
     new webpack.DefinePlugin({
@@ -172,7 +188,10 @@ export async function createConfig(
     },
     devtool: isDev ? 'eval-cheap-module-source-map' : 'source-map',
     context: paths.targetPath,
-    entry: [...(options.additionalEntryPoints ?? []), paths.targetEntry],
+    entry: {
+      main: [...(options.additionalEntryPoints ?? []), paths.targetEntry],
+      ...(paths.targetAuthEntry ? { auth: paths.targetAuthEntry } : {}),
+    },
     resolve: {
       extensions: ['.ts', '.tsx', '.mjs', '.js', '.jsx', '.json', '.wasm'],
       mainFields: ['browser', 'module', 'main'],

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

@@ -38,6 +38,14 @@ export function resolveBundlingPaths(options: BundlingPathsOptions) {
     return resolvePath(targetDir, `${pathString}.js`);
   };
 
+  const resolveTargetOptionalModule = (pathString: string) => {
+    try {
+      return resolveTargetModule(pathString);
+    } catch {
+      return undefined;
+    }
+  };
+
   let targetPublic = undefined;
   let targetHtml = resolvePath(targetDir, 'public/index.html');
 
@@ -51,12 +59,18 @@ export function resolveBundlingPaths(options: BundlingPathsOptions) {
     }
   }
 
+  let targetAuthHtml = targetHtml;
+  if (fs.pathExistsSync(resolvePath(targetDir, 'public/auth.html'))) {
+    targetAuthHtml = resolvePath(targetDir, 'public/auth.html');
+  }
+
   // Backend plugin dev run file
   const targetRunFile = resolvePath(targetDir, 'src/run.ts');
   const runFileExists = fs.pathExistsSync(targetRunFile);
 
   return {
     targetHtml,
+    targetAuthHtml,
     targetPublic,
     targetPath: resolvePath(targetDir, '.'),
     targetRunFile: runFileExists ? targetRunFile : undefined,
@@ -65,6 +79,7 @@ export function resolveBundlingPaths(options: BundlingPathsOptions) {
     targetSrc: resolvePath(targetDir, 'src'),
     targetDev: resolvePath(targetDir, 'dev'),
     targetEntry: resolveTargetModule(entry),
+    targetAuthEntry: resolveTargetOptionalModule('src/auth'),
     targetTsConfig: paths.resolveTargetRoot('tsconfig.json'),
     targetPackageJson: resolvePath(targetDir, 'package.json'),
     rootNodeModules: paths.resolveTargetRoot('node_modules'),