spring-boot-microservice-simplest

This github repository consist of 4 microservices:

1. eureka-server: A microservice registry server. All other microservices will register with this server and can used to get information about other microservices.

   Important Annotation(s): @EnableEurekaServer

   Application.properties

   spring.application.name=Eureka-server
   # Eureka server is client as well so prevent registering with itself
   eureka.client.register-with-eureka=false
   # Default Eureka server port
   server.port=8761
   

2. employee-eureka-client: A small microservice with single endpoint . It will register itself with eureka-server.

   Important Annotation(s): @EnableEurekaClient

   Application.properties

   spring.application.name=Employee-service
   # Just a number. If you are deploying multiple instance of this service
   # you can change the number. This will reflect in endpoint response
   number=1
   # Tomcat port
   server.port=3333
   

3. person-eureka-client: It is same as employee-eureka-client but the endpoint will return a different text. Also it has a additional endpoint that make a call to employee-eureka-client using RestTemplate instead of hardcoding the url like this:

   restTemplate.getForObject("http://localhost:3333/", String.class);

   we change to this:

   restTemplate.getForObject("http://employee-service/", String.class);

   In this case employee-service is equivalent to localhost:3333, This information is fetch from Eureka-server and will be stored in cache for further use. if there are muliple employee-eureka-client microservice running then the http call will be load balanced automactically using netflix ribbon.

   Important Annotation(s) : @EnableEurekaClient, @LoadBalanced

   Application.properties

   spring.application.name=Person-service
   # Just a number. If you are deploying multiple instance of this service
   # you can change the number. This will reflect in endpoint response
   number=1
   # Tomcat port
   server.port=4444
   

4. zuul-gateway: It is used as a gateway server which forwards the request to respective microservices along with load balancing. It also register with eureka and uses it to get information about other microservices

   Important Annotation(s): @EnableZuulProxy, @EnableDiscoveryClient

   Application.properties

   spring.application.name=zuul-gateway
   #routes to employee service app
   zuul.routes.employee.service-id=employee-service
   #routes to person service app
   zuul.routes.person.service-id=person-service
   

   Take a look at last two property in the properties file.

   zuul.routes.XXXX.service-id=YYYY

   The XXXX will be the route url and YYYY will be the spring.application.name text. Consider example:

   zuul.routes.person.service-id=person-service

   If any hit came with URL http://localhost:8080/person then it will be forward to person-service's root url . If there are multiple person-service running then it will be load balanced using ribbon . Below is the screenshot. I just changed the number=2 in application.properties of other person-service for identification