Hystrix, Zuul, Eureka

"Hystrix" is a circuit-breaker Pattern created by Netflix. 

https://techblog.constantcontact.com/software-development/circuit-breakers-and-microservices/

Its basically a fault-tolerance management library from spring

<!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-hystrix -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-hystrix</artifactId>
    <version>1.4.7.RELEASE</version>
</dependency>

Spring Cloud Starter Hystrix

Spring Cloud Starter Hystrix (deprecated, please use spring-cloud-starter-netflix-hystrix)

"Zuul"  -> API Gateway

"Eureka"  ->  Service Discovery