如何在AWS上实现OAuth 2.0 Web应用流保护自定义API？相关AWS服务咨询

Here's the breakdown of AWS services you'll need and how to implement the setup:

Core Services to Use #

• Amazon Cognito User Pools: Acts as your OAuth 2.0 identity provider (IdP). It manages user sign-up/sign-in, handles the authorization code grant flow (standard for web apps), and issues JWT access/refresh tokens.
• Amazon API Gateway: Serves as the entry point for your API. You’ll configure a Cognito-powered authorizer here to validate incoming requests—only those with valid tokens will be forwarded to your backend.

Step-by-Step Implementation #

1. Set Up a Cognito User Pool #

• In the AWS Cognito console, create a user pool. Under "App integration," add a web client and enable the Authorization Code Grant type (this is the OAuth 2.0 Web App Flow).
• Configure your web app’s callback and logout URLs (Cognito redirects users to these after authentication or logout).
• Save the User Pool ID, Client ID, and token endpoint URLs—you’ll need these for later integration.

2. Add a Cognito Authorizer to API Gateway #

• In API Gateway, create a new authorizer of type Cognito. Link it to your user pool, and set the token source to the Authorization header (expecting a Bearer <token> format).
• Attach this authorizer to all your API methods (GET, POST, etc.). Requests without a valid Cognito token will now be rejected with a 401 Unauthorized error.

3. Integrate Your Web App with Cognito #

• Implement the OAuth 2.0 Authorization Code Flow in your web app:
  1. Redirect users to Cognito’s authorization endpoint to initiate login.
  2. After successful login, Cognito sends an authorization code to your callback URL.
  3. Exchange this code for an access token and refresh token using Cognito’s token endpoint.
  4. Include the access token in the Authorization: Bearer <token> header when making requests to your API.

4. Optional: Enforce Scoped Access Control #

• For finer-grained permissions, define scopes in your Cognito User Pool (e.g., read:data, write:data).
• In API Gateway, update the authorizer to require specific scopes for each API method, ensuring users only access resources they’re permitted to.

5. Connect to Your Backend #

• API Gateway can forward validated requests to any AWS backend (Lambda, EC2, ECS, etc.). If using Lambda, you can access token claims (like user ID or scopes) directly in the Lambda event to add additional authorization logic.

Key Best Practices #

• Always use HTTPS for all interactions between your web app, Cognito, and API Gateway to prevent token interception.
• Use Cognito’s refresh tokens to obtain new access tokens without forcing users to re-authenticate frequently.
• Leverage Cognito’s Hosted UI to avoid building custom login pages, or integrate with third-party IdPs (Google, Facebook) if needed.

内容的提问来源于stack exchange，提问作者user1517566