In this chapter, we will discuss the next important element of microservice-based architecture, an API gateway. It is not our first encounter with that element in practice. We have already implemented a simple gateway pattern in Chapter 4, Service Discovery, for the purpose of presenting how a zoning mechanism works for service discovery with Eureka. We used Netflix's Zuul library, which is a JVM-based router and server-side load balancer. Netflix designed Zuul to provide features such as authentication, stress and canary testing, dynamic routing, and active/active multiregional traffic management. Although this is not explicitly stated, it also acts as a gateway in microservice architecture and its main task is to hide the complexity of your system from an external client.
Until now, Zuul, in fact, didn't have any competition when it came to API gateway pattern implementation inside the Spring Cloud framework. However, the situation is changing...
