Previously, we implemented service registration and discovery, and implemented the interface call in load balancing. However, our Eureka server is a single point. Although EurekaClient will connect to EurekaServer regularly to obtain the information in the registry and cache it to the local. If eurekacerver is unavailable, EurekaClient will not be updated, which will affect the call of microservice. Therefore, to have a highly available EurekaServer cluster, EurekaServer can realize highly available deployment by running multiple instances to register with each other. So as to ensure the data consistency.

Configure 3 eurekaservers

spring:
  profiles:  es01
  application:
    name: eurekserver
server:
  port: 8081
eureka:
  instance:
    hostname: localhost
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:8082/eureka/,http://${eureka.instance.hostname}:8083/eureka/

---

spring:
  profiles:  es02
  application:
    name: eurekserver
server:
  port: 8082
eureka:
  instance:
    hostname: localhost
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:8081/eureka/,http://${eureka.instance.hostname}:8083/eureka/

---


spring:
  profiles:  es03
  application:
    name: eurekserver
server:
  port: 8083
eureka:
  instance:
    hostname: localhost
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:8081/eureka/,http://${eureka.instance.hostname}:8082/eureka/

Now let's run through the examples used in the last section.

Eureka discovery configuration. Here we only configure the address of one Eureka server. To test more clearly, we need to copy Eureka server.

spring:
  profiles: dis01
  application:
    name: eurekadiscovery
server:
  port: 8001
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8081/eureka/

---

spring:
  profiles: dis02
  application:
    name: eurekadiscovery
server:
  port: 8002
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8081/eureka/

Eureka discovery 2 configuration. Here we only have the 8082 Eureka server

spring:
  application:
    name: eurekadiscovery2
server:
  port: 8003
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8082/eureka/

Start the three instances respectively.

http://localhost:8081/  http://localhost:8082/   http://localhost:8083/

As you can see, the three instances have been registered successfully, and the three eurekaservers have been replicated. implement http://localhost:8003/hi?name=sl , EurekaDiscovery 2 can successfully discover and call EurekaDiscovery instance.