Merge pull request #22434 from backstage/rugvip/authentry

cli: add support for a separate /public entry point

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

@@ -25,7 +25,7 @@ import {
 import formatWebpackMessages from 'react-dev-utils/formatWebpackMessages';
 import { createConfig, resolveBaseUrl } from './config';
 import { BuildOptions } from './types';
-import { resolveBundlingPaths } from './paths';
+import { resolveBundlingPaths, resolveOptionalBundlingPaths } from './paths';
 import chalk from 'chalk';
 import { createDetectedModulesEntryPoint } from './packageDetection';
 
@@ -47,18 +47,44 @@ export async function buildBundle(options: BuildOptions) {
     targetPath: paths.targetPath,
   });
 
-  const config = await createConfig(paths, {
+  const commonConfigOptions = {
     ...options,
     checksEnabled: false,
     isDev: false,
     baseUrl: resolveBaseUrl(options.frontendConfig),
     getFrontendAppConfigs: () => options.frontendAppConfigs,
-    additionalEntryPoints: detectedModulesEntryPoint,
+  };
+  const configs = [
+    await createConfig(paths, {
+      ...commonConfigOptions,
+      additionalEntryPoints: detectedModulesEntryPoint,
+    }),
+  ];
+
+  const publicPaths = await resolveOptionalBundlingPaths({
+    entry: 'src/index-public-experimental',
+    dist: 'dist/public',
   });
+  if (publicPaths) {
+    console.log(
+      chalk.yellow(
+        `⚠️  WARNING: The app /auth entry point is an experimental feature that may receive immediate breaking changes.`,
+      ),
+    );
+    configs.push(
+      await createConfig(publicPaths, {
+        ...commonConfigOptions,
+        publicSubPath: '/public',
+      }),
+    );
+  }
 
   const isCi = yn(process.env.CI, { default: false });
 
   const previousFileSizes = await measureFileSizesBeforeBuild(paths.targetDist);
+  const previousAuthSizes = publicPaths
+    ? await measureFileSizesBeforeBuild(publicPaths.targetDist)
+    : undefined;
   await fs.emptyDir(paths.targetDist);
 
   if (paths.targetPublic) {
@@ -76,33 +102,43 @@ export async function buildBundle(options: BuildOptions) {
     );
   }
 
-  const { stats } = await build(config, isCi);
+  const { stats } = await build(configs, isCi);
 
   if (!stats) {
     throw new Error('No stats returned');
   }
+  const [mainStats, authStats] = stats.stats;
 
   if (statsJsonEnabled) {
     // No @types/bfj
     await require('bfj').write(
       resolvePath(paths.targetDist, 'bundle-stats.json'),
-      stats.toJson(),
+      mainStats.toJson(),
     );
   }
 
   printFileSizesAfterBuild(
-    stats,
+    mainStats,
     previousFileSizes,
     paths.targetDist,
     WARN_AFTER_BUNDLE_GZIP_SIZE,
     WARN_AFTER_CHUNK_GZIP_SIZE,
   );
+  if (publicPaths && previousAuthSizes) {
+    printFileSizesAfterBuild(
+      authStats,
+      previousAuthSizes,
+      publicPaths.targetDist,
+      WARN_AFTER_BUNDLE_GZIP_SIZE,
+      WARN_AFTER_CHUNK_GZIP_SIZE,
+    );
+  }
 }
 
-async function build(config: webpack.Configuration, isCi: boolean) {
-  const stats = await new Promise<webpack.Stats | undefined>(
+async function build(configs: webpack.Configuration[], isCi: boolean) {
+  const stats = await new Promise<webpack.MultiStats | undefined>(
     (resolve, reject) => {
-      webpack(config, (err, buildStats) => {
+      webpack(configs, (err, buildStats) => {
         if (err) {
           if (err.message) {
             const { errors } = formatWebpackMessages({

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

@@ -92,7 +92,7 @@ export async function createConfig(
   paths: BundlingPaths,
   options: BundlingOptions,
 ): Promise<webpack.Configuration> {
-  const { checksEnabled, isDev, frontendConfig } = options;
+  const { checksEnabled, isDev, frontendConfig, publicSubPath = '' } = options;
 
   const { plugins, loaders } = transforms(options);
   // Any package that is part of the monorepo but outside the monorepo root dir need
@@ -102,7 +102,11 @@ export async function createConfig(
 
   const baseUrl = frontendConfig.getString('app.baseUrl');
   const validBaseUrl = new URL(baseUrl);
-  const publicPath = validBaseUrl.pathname.replace(/\/$/, '');
+  let publicPath = validBaseUrl.pathname.replace(/\/$/, '');
+  if (publicSubPath) {
+    publicPath = `${publicPath}${publicSubPath}`.replace('//', '/');
+  }
+
   if (checksEnabled) {
     plugins.push(
       new ForkTsCheckerWebpackPlugin({

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

@@ -23,6 +23,8 @@ export type BundlingPathsOptions = {
   entry: string;
   // Target directory, defaulting to paths.targetDir
   targetDir?: string;
+  // Relative dist directory, defaulting to 'dist'
+  dist?: string;
 };
 
 export function resolveBundlingPaths(options: BundlingPathsOptions) {
@@ -60,7 +62,7 @@ export function resolveBundlingPaths(options: BundlingPathsOptions) {
     targetPublic,
     targetPath: resolvePath(targetDir, '.'),
     targetRunFile: runFileExists ? targetRunFile : undefined,
-    targetDist: resolvePath(targetDir, 'dist'),
+    targetDist: resolvePath(targetDir, options.dist ?? 'dist'),
     targetAssets: resolvePath(targetDir, 'assets'),
     targetSrc: resolvePath(targetDir, 'src'),
     targetDev: resolvePath(targetDir, 'dev'),
@@ -72,4 +74,14 @@ export function resolveBundlingPaths(options: BundlingPathsOptions) {
   };
 }
 
+export async function resolveOptionalBundlingPaths(
+  options: BundlingPathsOptions,
+) {
+  const resolvedPaths = resolveBundlingPaths(options);
+  if (await fs.pathExists(resolvedPaths.targetEntry)) {
+    return resolvedPaths;
+  }
+  return undefined;
+}
+
 export type BundlingPaths = ReturnType<typeof resolveBundlingPaths>;

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

@@ -32,7 +32,7 @@ import { loadCliConfig } from '../config';
 import { Lockfile } from '../versioning';
 import { createConfig, resolveBaseUrl } from './config';
 import { createDetectedModulesEntryPoint } from './packageDetection';
-import { resolveBundlingPaths } from './paths';
+import { resolveBundlingPaths, resolveOptionalBundlingPaths } from './paths';
 import { ServeOptions } from './types';
 import { hasReactDomClient } from './hasReactDomClient';
 
@@ -147,7 +147,7 @@ DEPRECATION WARNING: React Router Beta is deprecated and support for it will be
     },
   });
 
-  const config = await createConfig(paths, {
+  const commonConfigOptions = {
     ...options,
     checksEnabled: options.checksEnabled,
     isDev: true,
@@ -156,6 +156,10 @@ DEPRECATION WARNING: React Router Beta is deprecated and support for it will be
     getFrontendAppConfigs: () => {
       return latestFrontendAppConfigs;
     },
+  };
+
+  const config = await createConfig(paths, {
+    ...commonConfigOptions,
     additionalEntryPoints: detectedModulesEntryPoint,
   });
 
@@ -199,7 +203,26 @@ DEPRECATION WARNING: React Router Beta is deprecated and support for it will be
       root: paths.targetPath,
     });
   } else {
-    const compiler = webpack(config);
+    const publicPaths = await resolveOptionalBundlingPaths({
+      entry: 'src/index-public-experimental',
+      dist: 'dist/public',
+    });
+    if (publicPaths) {
+      console.log(
+        chalk.yellow(
+          `⚠️  WARNING: The app /public entry point is an experimental feature that may receive immediate breaking changes.`,
+        ),
+      );
+    }
+    const compiler = publicPaths
+      ? webpack([
+          config,
+          await createConfig(publicPaths, {
+            ...commonConfigOptions,
+            publicSubPath: '/public',
+          }),
+        ])
+      : webpack(config);
 
     webpackServer = new WebpackDevServer(
       {

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

@@ -26,6 +26,8 @@ export type BundlingOptions = {
   baseUrl: URL;
   parallelism?: number;
   additionalEntryPoints?: string[];
+  // Path to append to the detected public path, e.g. '/public'
+  publicSubPath?: string;
 };
 
 export type ServeOptions = BundlingPathsOptions & {