API Gateway
Lambda Function
Elastic Load Balancer
Legacy Application
A client application makes a request to an API Gateway endpoint.
If the route matches a Lambda Proxy route, traffic is directed to a Lambda function in your serverless component.
The Lambda Function processes the request and performs your business logic (such as fetching data from a DynamoDB Table). The results are returned to API Gateway and sent to the client.
If the route matches a HTTP Proxy route, the request is proxied via HTTP to your existing load balancers.
Your Legacy Application processes the request, performs your business logic, and returns the result through the load balancer to API Gateway, and then back to the client.
The client can be a web browser, an application, or even another service in AWS.
Amazon API Gateway with Lambda Proxy integrations to route traffic to new serverless components, and HTTP Proxy routes to direct traffic to legacy infrastucture.
A Lambda function that is part of a serverless microservice that replaces or enhances existing APIs.
A DynamoDB table that is part of your serverless microservice.
An Elastic Load Balancer (ALB, NLB, or Classic) that is perfoming health checks and routing HTTP traffic.
Your existing application that is handling API traffic from an Elastic Load Balancer.