ServiceRegistry

https://microservices.io/patterns/service-registry.html

服务注册和发现是分布式系统里面的Naming部分，并不是Communication部分。Communication是Feign做的。

nacos,zookeeper,etcd,consul,eureka

nacos:一个更易于构建云原生应用的动态服务发现、配置管理和服务管理平台。

zookeeper:Apache ZooKeeper is an effort to develop and maintain an open-source server which enables highly reliable distributed coordination.

etcd:A distributed, reliable key-value store for the most critical data of a distributed system

consul:Consul is a service networking solution to automate network configurations, discover services, and enable secure connectivity across any cloud or runtime.

eureka:Eureka is a RESTful (Representational State Transfer) service that is primarily used in the AWS cloud for the purpose of discovery, load balancing and failover of middle-tier servers. It plays a critical role in Netflix mid-tier infra.