27.10. Authentication and Authorization in APIs with API Gateway and Lambda

When it comes to backend development with Python, AWS Lambda and API Gateway are essential tools. However, security is a crucial aspect that must be considered. Authentication and authorization are two core elements of API security. In this chapter, we will discuss best practices for implementing authentication and authorization in APIs with API Gateway and Lambda.

Authentication vs. Authorization

Before diving into best practices, it's important to understand the difference between authentication and authorization. Authentication is the process of verifying a user's identity, while authorization is the process of verifying what an authenticated user is allowed to access.

Authentication with API Gateway and Lambda

There are several ways to implement authentication with API Gateway and Lambda. One of the best practices is to use AWS Cognito, a service that allows you to manage users and their sessions. Cognito allows you to create user pools, which are essentially databases of users. When a user authenticates, they receive a JWT token (JSON Web Token) that can be used to authenticate subsequent requests.

Here are some best practices for authenticating with API Gateway and Lambda:

• Use JWT tokens: JWT tokens are a standard and secure way to represent information between two parties. They are compact, self-contained, and can be sent via a URL, POST header, or in an HTTP header.
• Validate JWT tokens: When you receive a JWT token, always validate it before processing the request. This can be done using the Cognito user pool public key.
• Use HTTPS: Always use HTTPS to protect the transmission of JWT tokens and other sensitive information.

Authorization with API Gateway and Lambda

Authorization is the process of determining what an authenticated user is allowed to do. With API Gateway and Lambda, you can implement authorization at the function level or resource level.

Here are some best practices for authorization with API Gateway and Lambda:

• Use IAM policies: IAM (Identity and Access Management) policies let you control who can access your AWS resources and what they can do with them. You can attach IAM policies to Lambda functions to control access to resources.
• Use AWS Resource Policy: AWS resource policies let you control who can invoke your Lambda functions. You can create a resource policy that only allows invocations from a certain API Gateway.
• Use AWS Cognito for user groups: With Cognito, you can create user groups and assign IAM policies to those groups. This allows you to control access to resources based on a user's user group.

Conclusion

Authentication and authorization are crucial aspects of API security. With API Gateway and Lambda, you can implement these aspects effectively and securely. Keep the best practices discussed in this chapter in mind when developing your APIs.