Spring Cloud has implemented an embedded Zuul proxy to allow frontend application's proxy calls to backend services. This feature is useful for external clients, because it hides system complexity and helps to avoid the need to manage CORS and authentication concerns independently for all microservices. To enable it, you should annotate a Spring Boot main class with @EnableZuulProxy, and this forwards incoming requests to the target service. Of course, Zuul is integrated with the Ribbon load balancer, Hystrix circuit breaker, and service discovery, for example with Eureka.
Let's go back to the example from the previous chapter to append the last element in the microservice-based architecture, API Gateway. What we haven't considered yet is how the external client would call our services. First, we would not want to expose the network addresses of all microservices running inside the system. We may also perform some operations such...