Spring Boot Hystrix Sample - tomoTaka’s blog

昨日までの、Spring Cloud Eureka server, service discovery, Ribbon に今回はHystrix(Circuit Breaker)を追加してみました。
tomotaka.hatenablog.com

イメージは、こんな感じかな？
f:id:tomoTaka:20180102133929p:plain

work service

1,2,3,4 and 5秒かかるサービスのapi(port:8001,8002 で公開)

package com.example.eurekaclinet.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Random;
import java.util.concurrent.TimeUnit;

@RestController
public class WorkServiceController {
    private static final Logger logger = LoggerFactory.getLogger(WorkServiceController.class);
    @Value("${server.port}")
    private int port;
    private Random random = new Random();

    @RequestMapping("/work")
    public String work() {
        int i = random.nextInt(5) + 1;
        logger.info("start work with {} sec", i);
        try {
            TimeUnit.SECONDS.sleep(Long.valueOf(i));
        } catch (InterruptedException e) {
            logger.error("work error", e);
            throw new RuntimeException(e.getMessage());
        }
        String work = String.format("%d sec work done. port=[%d]", i, port);
        return work;
    }
}

call work service

sample アプリが、上記のapiをcall
@ HystrixCommand annotationで、タイムアウト3100 millisecを設定しているので、4,5秒の処理では、レスポンスがfallbackMethodメソッドで設定している固定値「work not yet done.」を返却。

package com.example.eurekafeign.controller;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class WorkController {
    private static final Logger logger = LoggerFactory.getLogger(WorkController.class);
    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping("/work/eureka")
    @HystrixCommand(fallbackMethod = "workFallback", commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3100")
    })
    public String work() {
        logger.info("start work from eureka");
        String work = restTemplate.getForObject("http://greeting-service/work", String.class);
        logger.info("end work from eureka");
        return work;
    }

    public String workFallback() {
        return "work not yet done.";
    }
}