Security is a crucial part of any application, and when we talk about APIs, it is no different. Authorization in API Gateway is a vital part of ensuring that only authorized users have access to API resources. In this chapter, we will explore security in API Gateway in depth, with a focus on authorization.
What is Authorization in API Gateway?
Authorization in API Gateway is the process of determining what an authenticated user can do. For example, an authenticated user might have permission to create, read, update, and delete (CRUD) resources in an API, while another user might only have read permissions.
AWS API Gateway offers several options for access control, including AWS Identity and Access Management (IAM), Lambda authorizers (formerly known as custom authorizers), and Amazon Cognito User Pools.
Authorization with AWS IAM
AWS IAM is a service that helps you control access to AWS resources. With IAM, you can create and manage AWS users and groups, and use permissions to allow or deny access to AWS resources.
To use IAM with API Gateway, you first create an IAM policy that grants permissions to invoke API operations. You then attach this policy to an IAM user, group, or role. When a client makes an API call, API Gateway verifies that the caller has the required credentials and that the associated IAM policy allows the call.
Authorization with Lambda Authorizers
Lambda authorizers are Lambda functions that you create to control access to your APIs. When a client makes a request to an API with a Lambda authorizer, the Lambda authorizer runs the authorization logic you defined to determine whether the caller is authorized to invoke the API.
Lambda authorizers return authorization policies that are used by API Gateway to allow or deny access to the API. You can create Lambda authorizers that authorize access based on identity tokens (for example, a JWT token issued by an identity provider), or you can create Lambda authorizers that authorize access based on custom authorization requests.
Authorization with Amazon Cognito User Pools
Amazon Cognito User Pools is a service that helps you manage users and their authentications. With User Pools, you can create a user directory for your application, allow users to sign up and sign in, and retrieve tokens for users.
To use User Pools with API Gateway, you first create a User Pool and configure API Gateway to use the User Pool as an authorizer. When a client makes an API call, API Gateway verifies that the user's token is valid and that the user is authorized to make the call.
Conclusion
In summary, authorization in API Gateway is an essential part of API security. Whether using IAM, Lambda authorizers, or User Pools, it's important that you correctly configure authorization to protect your API resources. Remember that security is an ongoing aspect of software development and must be considered at every stage of the development lifecycle.
