From 91e03b04eea25cdfe2c1e061f27f437a254c8073 Mon Sep 17 00:00:00 2001
From: Hui Zhao <zhohz@amazon.com>
Date: Tue, 29 Oct 2024 11:21:42 -0700
Subject: [PATCH] chore: adding warnings regarding using custom endpoints

---
 .../__tests__/singleton/Auth/index.test.ts    | 52 +++++++++++++++++++
 packages/core/src/singleton/Auth/index.ts     | 17 ++++++
 packages/core/src/singleton/Auth/types.ts     |  6 +++
 3 files changed, 75 insertions(+)
 create mode 100644 packages/core/__tests__/singleton/Auth/index.test.ts

diff --git a/packages/core/__tests__/singleton/Auth/index.test.ts b/packages/core/__tests__/singleton/Auth/index.test.ts
new file mode 100644
index 00000000000..e08f838cfe5
--- /dev/null
+++ b/packages/core/__tests__/singleton/Auth/index.test.ts
@@ -0,0 +1,52 @@
+import { ConsoleLogger } from '../../../src/Logger';
+import { AuthClass } from '../../../src/singleton/Auth';
+
+jest.mock('../../../src/Logger', () => {
+	const warn = jest.fn();
+
+	return {
+		ConsoleLogger: jest.fn(() => ({
+			warn,
+		})),
+	};
+});
+
+describe('Auth', () => {
+	const auth = new AuthClass();
+	const logger = new ConsoleLogger('Auth');
+	const mockedWarn = logger.warn as jest.Mock;
+
+	describe('configure', () => {
+		const mockConfig = {
+			userPoolClientId: 'userPoolClientId',
+			userPoolId: 'userPoolId',
+		};
+
+		it('prints warning when use custom endpoint for Cognito User Pool', () => {
+			auth.configure({
+				Cognito: {
+					...mockConfig,
+					userPoolEndpoint: 'https://custom-endpoint.com',
+				},
+			});
+
+			expect(mockedWarn).toHaveBeenCalledWith(
+				expect.stringContaining('Amazon Cognito User Pool'),
+			);
+		});
+
+		it('prints warning when use custom endpoint for Cognito Identity Pool', () => {
+			auth.configure({
+				Cognito: {
+					...mockConfig,
+					identityPoolId: 'identityPoolId',
+					identityPoolEndpoint: 'https://custom-endpoint.com',
+				},
+			});
+
+			expect(mockedWarn).toHaveBeenCalledWith(
+				expect.stringContaining('Amazon Cognito Identity Pool'),
+			);
+		});
+	});
+});
diff --git a/packages/core/src/singleton/Auth/index.ts b/packages/core/src/singleton/Auth/index.ts
index 245cc704b0c..e45ca7135f6 100644
--- a/packages/core/src/singleton/Auth/index.ts
+++ b/packages/core/src/singleton/Auth/index.ts
@@ -1,5 +1,7 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+import { ConsoleLogger } from '../../Logger';
+
 import {
 	AuthConfig,
 	AuthSession,
@@ -9,6 +11,8 @@ import {
 	LibraryAuthOptions,
 } from './types';
 
+const logger = new ConsoleLogger('Auth');
+
 export function isTokenExpired({
 	expiresAt,
 	clockDrift,
@@ -41,6 +45,16 @@ export class AuthClass {
 	): void {
 		this.authConfig = authResourcesConfig;
 		this.authOptions = authOptions;
+
+		if (authResourcesConfig.Cognito.userPoolEndpoint) {
+			logger.warn(getCustomEndpointWarningMessage('Amazon Cognito User Pool'));
+		}
+
+		if (authResourcesConfig.Cognito.identityPoolEndpoint) {
+			logger.warn(
+				getCustomEndpointWarningMessage('Amazon Cognito Identity Pool'),
+			);
+		}
 	}
 
 	/**
@@ -106,3 +120,6 @@ export class AuthClass {
 		);
 	}
 }
+
+const getCustomEndpointWarningMessage = (target: string): string =>
+	`You are using a custom Amazon ${target} endpoint, ensure the endpoint is correct.`;
diff --git a/packages/core/src/singleton/Auth/types.ts b/packages/core/src/singleton/Auth/types.ts
index acd61f8d91d..8eb903c0487 100644
--- a/packages/core/src/singleton/Auth/types.ts
+++ b/packages/core/src/singleton/Auth/types.ts
@@ -135,6 +135,9 @@ export interface AuthIdentityPoolConfig {
 
 export interface CognitoIdentityPoolConfig {
 	identityPoolId: string;
+	/**
+	 * Use this field to specify a custom endpoint for the Amazon Cognito identity pool. Ensure this endpoint is correct and valid.
+	 */
 	identityPoolEndpoint?: string;
 	allowGuestAccess?: boolean;
 }
@@ -152,6 +155,9 @@ export type CognitoUserPoolConfigMfaStatus = 'on' | 'off' | 'optional';
 export interface CognitoUserPoolConfig {
 	userPoolClientId: string;
 	userPoolId: string;
+	/**
+	 * Use this field to specify a custom endpoint for the Amazon Cognito user pool. Ensure this endpoint is correct and valid.
+	 */
 	userPoolEndpoint?: string;
 	signUpVerificationMethod?: 'code' | 'link';
 	loginWith?: {