Amazon API Gateway

API Gateway is a service that helps you to build RESTful APIs. You need to configure your resources, set the supported HTTP verbs and specify what will handle the requests. You can use it to redirect requests to EC2 instances (virtual machines) or external web servers, but what we'll explore here is to use it to trigger Lambda functions.

Besides, API Gateway has other interesting features. For example, after creating your API endpoints, you can use API Gateway to automatically generate a client SDK for many different platforms, where you can easily test and distribute it to be used by third-party developers. Also, you can create third-party API keys to access your content with fine-grained access permissions, request quota limits, and throttling.

In our architecture, API Gateway will act as a thin layer that exists only to expose our Lambda functions to the world. Additionally, you can set security controls to allow only authenticated users to trigger your code. We are going to use this service in the next chapter, where we'll talk about how to configure our endpoints using the Serverless Framework, we will see more in Chapter 6, Developing the Backend, while building our backend code, and lastly, in Chapter 8, Securing the Serverless Application, when our security measures will be explained.