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...