app-next,docs: add example for public index entry point in new frontend system

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

packages/app-next/src/App.tsx

@@ -36,18 +36,13 @@ import { convertLegacyApp } from '@backstage/core-compat-api';
 import { FlatRoutes } from '@backstage/core-app-api';
 import { Route } from 'react-router';
 import { CatalogImportPage } from '@backstage/plugin-catalog-import';
-import {
-  createApiFactory,
-  configApiRef,
-  SignInPageProps,
-} from '@backstage/core-plugin-api';
+import { createApiFactory, configApiRef } from '@backstage/core-plugin-api';
 import {
   ScmAuth,
   ScmIntegrationsApi,
   scmIntegrationsApiRef,
 } from '@backstage/integration-react';
-import { createSignInPageExtension } from '@backstage/frontend-plugin-api';
-import { SignInPage } from '@backstage/core-components';
+import { signInPageOverrides } from './overrides/SignInPage';
 
 /*
 
@@ -90,12 +85,6 @@ const homePageExtension = createExtension({
   },
 });
 
-const signInPage = createSignInPageExtension({
-  name: 'guest',
-  loader: async () => (props: SignInPageProps) =>
-    <SignInPage {...props} providers={['guest']} />,
-});
-
 const scmAuthExtension = createApiExtension({
   factory: ScmAuth.createDefaultApiFactory(),
 });
@@ -121,13 +110,13 @@ const app = createApp({
     userSettingsPlugin,
     homePlugin,
     appVisualizerPlugin,
+    signInPageOverrides,
     ...collectedLegacyPlugins,
     createExtensionOverrides({
       extensions: [
         homePageExtension,
         scmAuthExtension,
         scmIntegrationApi,
-        signInPage,
         notFoundErrorPage,
       ],
     }),

packages/app-next/src/index-public-experimental.tsx

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { CookieAuthRedirect } from '@backstage/plugin-auth-react';
+import { createApp } from '@backstage/frontend-app-api';
+import { signInPageOverrides } from './overrides/SignInPage';
+import {
+  coreExtensionData,
+  createExtension,
+  createExtensionOverrides,
+} from '@backstage/frontend-plugin-api';
+
+const authRedirectExtension = createExtension({
+  namespace: 'app',
+  name: 'layout',
+  attachTo: { id: 'app/root', input: 'children' },
+  output: {
+    element: coreExtensionData.reactElement,
+  },
+  factory: () => ({
+    element: <CookieAuthRedirect />,
+  }),
+});
+
+const app = createApp({
+  features: [
+    signInPageOverrides,
+    createExtensionOverrides({
+      extensions: [authRedirectExtension],
+    }),
+  ],
+});
+
+ReactDOM.createRoot(document.getElementById('root')!).render(app.createRoot());

packages/app-next/src/overrides/SignInPage.tsx

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import React from 'react';
+import { SignInPage } from '@backstage/core-components';
+import {
+  createExtensionOverrides,
+  createSignInPageExtension,
+} from '@backstage/frontend-plugin-api';
+
+const signInPage = createSignInPageExtension({
+  name: 'guest',
+  loader: async () => props => <SignInPage {...props} providers={['guest']} />,
+});
+
+export const signInPageOverrides = createExtensionOverrides({
+  extensions: [signInPage],
+});