netflix-feign.md

Read more about Netflix Feign

Feign is a declarative, templated HTTP client that makes building web service easier. We can use Feign by create a interface and annotate it. Feign supports pluggable annotation, includes Feign annotate and JAX-RS annotate. Feign support pluggable encoders and decoders. When we use Feign, Spring Cloud integrated Ribbon and Eureka to provide load balancing.

In short: 1) Feign is using interface annotation; 2) Feign is integrated with Ribbon

Build Feign service

• Build mvn and name it feign (check pom.xml in example code), core dependencies:

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-ribbon</artifactId>
  </dependency>
  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-feign</artifactId>
  </dependency>       
  

• Start the configuration server by adding @EnableFeignServer in the Application class of application entry

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

• Create a remote call service

  @FeignClient("eureka-service")
  public interface RemoteInvokerService {
       
      @RequestMapping(value = "/demo/show", method = RequestMethod.GET)
      public String remoteInvoker();
  }
  

  eureka-service is the service that we register in the eureka module

  remote call /demo/show REST interface, can replace it with ／demo/index etc.

• Configuration

  spring.application.name=feign
  server.port=5000
  eureka.client.serviceUrl.defaultZone=http://${EUREKA_HOST}:${EUREKA_PORT}/eureka/
  eureka.instance.preferIpAddress=true      
  

  EUREKA_HOST：registry ip

  EUREKA_PORT：registry interface

• Address

  http://DOCKER_HOST:DOCKER_PORT/feign