What is an API Gateway? An API gateway is a server (or L7 proxy) between a client and microservices that acts as a centralized entry point for all clients into the system. It is a reverse proxy that accepts client API calls and forwards them to the appropriate microservice (refer to Fig. A below). By providing an API for each client, API gateways encapsulate the complexity of the underlying system and let clients talk to it instead of calling specific services. They also perform security checks (authentication and authorization) before the traffic reaches the service, thus leaving services to focus on their core functionalities. The need for API gateways for microservices The challenges posed by the direct client-to-microservices pattern of communication led to the popularity of API gateways. Let us go through some of them. The problem of service discovery and traffic routing For direct client-to-microservice connection, the clients have to know the specific endpoints of service ...