background

Let's first look at feign's separate article Feign declarative client interface

Many tools in spring cloud are used together. feign integrates ribbon and hystrix and provides a declarative consumer client. We use these tools together

• ribbon -- load balancing, retry

• hystrix - circuit breaker (degraded, fused)

Replace hystrix+ribbon with feign

feign + ribbon load balancing and retry

1 - load balancing

Without additional configuration, feign has enabled ribbon load balancing and retry mechanism, and parameters can be called through configuration

ConnectTimeout=1000
ReadTimeout=1000
MaxAutoRetries=0
MaxAutoRetriesNextServer=1

2 - configure ribbon timeout and retry

• ribbon - global configuration
• Item service -- configuration of a specific service instance

spring:
  application:
    name: feign
    
server:
  port: 3001
  
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka
      
ribbon:
  ConnectTimeout: 1000
  ReadTimeout: 1000
  
item-service:
  ribbon:
    MaxAutoRetries: 1
    MaxAutoRetriesNextServer: 2
    ConnectTimeout: 1000
    ReadTimeout: 500

Start service, access test

http://localhost:3001/item-service/35

Tips:

Overloading is generally not used very much. It depends on the requirements of the project. It can only be used if necessary

Load balancing is available by default. Depending on the situation, it can only be used if the project needs it

feign + hystrix downgrade

Enable hystrix - hyfe1

feign does not enable hystrix by default. Add configuration and enable hystrix

1.1 - application.yml add configuration

feign:
  hystrix:
    enabled: true

1.2 access the service after enabling hystrix

http://localhost:3001/item-service/35

By default, 1 second will fail quickly. When there is no degradation method, the whiteboard page will be displayed

2 - feign implements hystrix degradation

Specify a degraded class in the remote interface

Target: if the remote call fails, the code in the degraded class will be executed

2 - 1 remote interface (Interface)

ItemClient

@FeignClient(name="item-service",fallback = ItemClientFB.class)
public interface ItemClient {
...
...

OrderClient

...
@FeignClient(name="order-service",fallback = OrderClientFB.class)
public interface OrderClient{
...

UserClient

...
@FeignClient(name="user-service",fallback = UserClientFB.class)
public interface UserClient{
...

2 - 2 degraded

Degraded classes need to implement remote interfaces

ItemClientFB

@Component
public class ItemClientFB implements ItemClient{
    @Override
    public JsonResult<List<Item>> getItems(String orderId) {
        return JsonResult.err().msg("Failed to call product");
    }

    @Override
    public JsonResult<?> decreaseNumber(List<Item> items) {
        return JsonResult.err().msg("Failed to call product");
    }
}

OrderClientFB

@Component
public class OrderClientFB implements OrderClient{
    @Override
    public JsonResult<Order> getOrder(String orderId) {
        return JsonResult.err().msg("Call order failed");
    }

    @Override
    public JsonResult<?> saveOrder() {
        return JsonResult.err().msg("Call order failed");
    }
}

UserClientFB

@Component
public class UserClientFB implements UserClient{
    @Override
    public JsonResult<User> getUser(Integer userId) {
        return JsonResult.err().msg("Failed to call user");
    }

    @Override
    public JsonResult<?> addScore(Integer userId, Integer score) {
        return JsonResult.err().msg("Failed to call user");
    }
}

2 - 3 start service, access test

http://localhost:3001/item-service/35

After the call fails, jump to the degraded object (degraded successfully)

feign + hystrix monitoring

1 - pom. Adding hystrix dependency to XML

feign does not contain a complete hystrix dependency

1 - 1 xml dependency

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>

1 - 2 visual dependencies

Add @ enablercircuitbreaker to the main program

@EnableCircuitBreaker
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Sp09FeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(Sp09FeignApplication.class, args);
    }

}

2 - configure actor to expose hystrix Stream monitoring endpoint

View POM XML and confirm that the actor dependency has been added

2 - 1 actor dependency

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

2 - 2 application.yml exposed hystrix Stream endpoint

management:
  endpoints:
    web:
      exposure:
        include: hystrix.stream

3 - start the service and view the monitoring endpoint

http://localhost:3001/actuator

4 - hystrix dashboard

If you don't have a hystrix dashboard instrument or have not learned it, please come in hystrix dashboard circuit breaker instrument panel

Start the hystrix dashboard service, fill in the feign monitoring path, and start monitoring

• To access the instrument server: http://localhost:4001/hystrix

• Fill in feign monitoring path: http://localhost:3001/actuator/hystrix.stream

• Access microservices to generate monitoring data

To access the business server: http://localhost:3001/item-service/35