feat(amplify): add SPA redirect custom rule (#7320)

Refactor `CustomRule` to an enum-like class and add a static property
`SINGLE_PAGE_APPLICATION_REDIRECT` that sets up a 200 rewrite for all
files to `index.html` except for the following file extensions: css,
gif, ico, jpg, js, png, txt, svg, woff, ttf, map, json, webmanifest.

Author: jogold

packages/@aws-cdk/aws-amplify/README.md

@@ -83,6 +83,16 @@ amplifyApp.addCustomRule({
 });
 ```
 
+When working with a single page application (SPA), use the
+`CustomRule.SINGLE_PAGE_APPLICATION_REDIRECT` to set up a 200
+rewrite for all files to `index.html` except for the following
+file extensions: css, gif, ico, jpg, js, png, txt, svg, woff,
+ttf, map, json, webmanifest.
+
+```ts
+mySinglePageApp.addCustomRule(amplify.CustomRule.SINGLE_PAGE_APPLICATION_REDIRECT);
+```
+
 Add a domain and map sub domains to branches:
 ```ts
 const domain = amplifyApp.addDomain('example.com');

packages/@aws-cdk/aws-amplify/lib/app.ts

@@ -375,30 +375,94 @@ export enum RedirectStatus {
 }
 
 /**
- * Custom rewrite/redirect rule for an Amplify App.
+ * Options for a custom rewrite/redirect rule for an Amplify App.
  */
-export interface CustomRule {
+export interface CustomRuleOptions {
   /**
    * The source pattern for a URL rewrite or redirect rule.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
    */
   readonly source: string;
 
   /**
    * The target pattern for a URL rewrite or redirect rule.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
    */
   readonly target: string
 
   /**
    * The status code for a URL rewrite or redirect rule.
    *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   *
    * @default PERMANENT_REDIRECT
    */
   readonly status?: RedirectStatus;
 
   /**
    * The condition for a URL rewrite or redirect rule, e.g. country code.
    *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   *
    * @default - no condition
    */
   readonly condition?: string;
 }
+
+/**
+ * Custom rewrite/redirect rule for an Amplify App.
+ *
+ * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+ */
+export class CustomRule {
+  /**
+   * Sets up a 200 rewrite for all paths to `index.html` except for path
+   * containing a file extension.
+   */
+  public static readonly SINGLE_PAGE_APPLICATION_REDIRECT = new CustomRule({
+    source: '</^[^.]+$/>',
+    target: '/index.html',
+    status: RedirectStatus.REWRITE,
+  });
+
+  /**
+   * The source pattern for a URL rewrite or redirect rule.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   */
+  public readonly source: string;
+
+  /**
+   * The target pattern for a URL rewrite or redirect rule.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   */
+  public readonly target: string;
+
+  /**
+   * The status code for a URL rewrite or redirect rule.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   *
+   * @default PERMANENT_REDIRECT
+   */
+  public readonly status?: RedirectStatus;
+
+  /**
+   * The condition for a URL rewrite or redirect rule, e.g. country code.
+   *
+   * @see https://docs.aws.amazon.com/amplify/latest/userguide/redirects.html
+   *
+   * @default - no condition
+   */
+  public readonly condition?: string;
+
+  constructor(options: CustomRuleOptions) {
+    this.source = options.source;
+    this.target = options.target;
+    this.status = options.status;
+    this.condition = options.condition;
+  }
+}

packages/@aws-cdk/aws-amplify/test/app.test.ts

@@ -261,6 +261,29 @@ test('with custom rules', () => {
   });
 });
 
+test('with SPA redirect', () => {
+  // WHEN
+  new amplify.App(stack, 'App', {
+    sourceCodeProvider: new amplify.GitHubSourceCodeProvider({
+      owner: 'aws',
+      repository: 'aws-cdk',
+      oauthToken: SecretValue.plainText('secret'),
+    }),
+    customRules: [amplify.CustomRule.SINGLE_PAGE_APPLICATION_REDIRECT],
+  });
+
+  // THEN
+  expect(stack).toHaveResource('AWS::Amplify::App', {
+    CustomRules: [
+      {
+        Source: '</^[^.]+$/>',
+        Status: '200',
+        Target: '/index.html',
+      },
+    ],
+  });
+});
+
 test('with auto branch creation', () => {
   // WHEN
   const app = new amplify.App(stack, 'App', {