We can use Microservice Discovery Patterns and Service Registry for explaining this pattern. As the name suggests it will provide to register and discover microservices in the cluster.

As you know that, we have added API Gateways for routing the traffic with client and internal microservices. But How API GWs access the internal backend microservices ? How API Gateways know the target ip and port numbers for backend microservices ?

In that stage, the solution is applying Service Registry Pattern.

Because, in a Microservices based application, we have many instances of the several services on the different server. Due to dynamically changes in the ips and port numbers of these services, it is much more difficult to manage service discovery operations.

https://medium.com/design-microservices-architecture-with-patterns/service-registry-pattern-75f9c4e50d09