Configure Discovery Server (HA Setup)

We will set up a Netflix Eureka service registry, to which a client will both registers itself and uses it to resolve its own host. A service registry is useful because it enables client-side load-balancing and decouples service providers from consumers without the need for DNS.

Prerequisites

Before we begin, it’s recommended to have already completed Spring Config Server and Spring Config Client.

Maven Configuration

<dependency>
  <groupId>org.springframework.cloud</groupId>  
  <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>  
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-config</artifactId>
</dependency>

Start a Eureka Service Registry

Spring Cloud’s @EnableEurekaServer is used to stand up a registry with which other applications can communicate.

@SpringBootApplication
@EnableEurekaServer
public class SpringDiscoveryApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringDiscoveryApplication.class, args);
    }
}

Register with Config Server

Configure spring.cloud.config.uri with config server url in bootstrap.yml.

spring:
  application:
    name: discoveryserver
  cloud:
    config:
      uri: ${config.url:http://localhost:8001}
      name: discoveryserver

Setup External Configuration file in config server

Update the files with below naming convention, available under config folder as defined in config server.
discoveryserver-<profile>.yml

Setup Multiple Discovery Nodes

We will be setting up 2 instances (HA) of discovery server.

Node	Port	Profile
Node1	8101	node1
Node2	8102	node2

Setup Node 1

For node1 property file name will be discoveryserver-node1.yml

Add node2 URL for below property. (In our case node2 is running on port 8102)

eureka.client.service.url.defaultZone =http://localhost:8102/eureka/

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8102/eureka/
  region: default
spring:
  profiles: node1

Setup Node 2

For node2 property file name will be discoveryserver-node2.yml

Add node_1 _URL_ for below property. (In our case _node1 is running on port 8101)

eureka.client.service,url.defaultZone=https://localhost:8101/eureka/

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8101/eureka/
  region: default
spring:
  profiles: node2

Once the properties file of both nodes are updated, restart the config server.

Build the project

Execute mvn clean install to build the jar.

Test the Application

In order to test the application, we need to run two instances of jar file.

Run Node1
java -jar -Dspring.profiles.active=node1 -Dserver.port=8101 spring-discovery-1.0.0.jar

Run Node2*
java -jar -Dspring.profiles.active=node2 -Dserver.port=8102 spring-discovery-1.0.0.jar

Note: There might be some exceptions initially till both servers are up as they will try to connect to each other. Those can be ignored.

Once both the applications are running, we can test it by opening below url in browser.
Node 1 – http://localhost:8101/
Node 2 – http://localhost:8102/

You will notice that node1 has registered itself as replica in node2 and vice-versa.