cbirajdar / spring-boot-eureka-example Goto Github PK

Simple demo of service registration and discovery using Eureka.

Initial work based on this guide:

https://spring.io/guides/gs/service-registration-and-discovery/

Start the server

cd eureka-server
mvn spring-boot:run

Visit the Eureka dashboard at http://localhost:8761

Note that there are no 'Instances' yet registered

Start up a client

cd eureka-client
mvn spring-boot:run

Visit the client directly at http://localhost:8080/

The /whoami endpoint will show the client's self-knowledge of its application name and port

{
  "springApplicationName":"eureka-client",
  "serverPort":"8080"
}

The /instances endpoint will take up to a minute to update, but should eventually show all the instances of eureka-client that have been registered with the Eureka Discovery Client.

[
  {
    "host":"hostname",
    "port":8080,
    "serviceId":"EUREKA-CLIENT",
    "uri":"http://hostname:8080",
    "secure":false
  }
]

You can also visit the Eureka dashoboard again now and see it listed there.

You can see that another client will be registred by doing the following:

cd eureka-client
mvn spring-boot:run -Dspring.application.name=foo -Dserver.port=8081

The /whoami endpoint will show the name foo and the port 8081.

In a minute or so, the /instances endpoint will show the information about this foo instance too.

On the Eureka dashboard, two clients will now be registered.

Now try spinning up another instance of eureka-client by only over-riding the port parameter:

By default, Eureka uses the hostname as the instance name, so you have to override the eureka.instance.metadataMap.instanceId parameter when running two instances locally for testing. (reference)

cd eureka-client
mvn spring-boot:run -Dserver.port=8082 -Deureka.instance.metadataMap.instanceId=instance2

The /whoami endpoint for http://localhost:8082 shows what we expect.

In a minute or so, the /instances endpoint now shows two instances of eureka-client running.

The Eureka dashboard also shows 2 instances of eureka-client running.

Start up the zuul proxy application

cd zuul-proxy
mvn spring-boot:run

The proxy automatically maps a route based on the service names it finds in the eureka registry and uses client side load balancing.

Repeated requests to http://localhost:9999/eureka-client/whoami will show a different port depending on which instance it calls.