熔断器Hystrix及服务监控Dashboard

目标

1、服务雪崩效应
2、服务熔断服务降级
3、Hystrix默认超时时间设置
4、Hystrix服务监控Dashboard

服务雪崩效应

当一个请求依赖多个服务的时候：

正常情况下的访问

但是，当请求的服务中出现无法访问、异常、超时等问题时（图中的I），那么用户的请求将会被阻塞。

Hystrix的引入，可以通过服务熔断和服务降级来解决这个问题。

服务熔断服务降级

Hystrix断路器简介

hystrix对应的中文名字是“豪猪”，豪猪周身长满了刺，能保护自己不受天敌的伤害，代表了一种防御机制，这与hystrix本身的功能不谋而合，因此Netflix团队将该框架命名为Hystrix，并使用了对应的卡通形象做作为logo。

在一个分布式系统里，许多依赖不可避免的会调用失败，比如超时、异常等，如何能够保证在一个依赖出问题的情况下，不会导致整体服务失败，这个就是Hystrix需要做的事情。Hystrix提供了熔断、隔离、Fallback、cache、监控等功能，能够在一个、或多个依赖同时出现问题时保证系统依然可用。

Hystrix服务熔断服务降级@HystrixCommand fallbackMethod

熔断机制是应对雪崩效应的一种微服务链路保护机制。

当某个服务不可用或者响应时间超时，会进行服务降级，进而熔断该节点的服务调用，快速返回自定义的错误影响页面信息。

我们写个项目来测试下；

我们写一个新的带服务熔断的服务提供者项目 microservice-student-provider-hystrix-1004

把配置和代码都复制一份到这个项目里；

然后修改；

1，pom.xml加下 hystrix支持

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.jt</groupId>
        <artifactId>microservice</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>microservice-student-provider-hystrix-1004</artifactId>

    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <!--  修改后立即生效，热部署  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <dependency>
            <groupId>com.jt</groupId>
            <artifactId>microservice-common</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-netflix-eureka-client</artifactId>
            <version>1.4.5.RELEASE</version>
            <scope>compile</scope>
        </dependency>
        <!--添加注册中心Eureka相关配置-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <!--Hystrix相关依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <!-- actuator监控引入 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.jt</groupId>
            <artifactId>microservice-student-provider</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

2，application.yml修改下端口和实例名称

server:
  port: 1004
  context-path: /
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/xm1?useUnicode=true&characterEncoding=utf8
    username: root
    password: 123
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  application:
    name: microservice-student
  profiles: provider-hystrix-1004

eureka:
  instance:
    hostname: localhost
    appname: microservice-student
    instance-id: microservice-student:1004
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://eureka2001.jt.com:2001/eureka/,http://eureka2002.jt.com:2002/eureka/,http://eureka2003.jt.com:2003/eureka/

info:
  groupId: com.jt.testSpringcloud
  artifactId: microservice-student-provider-hystrix-1004
  version: 1.0-SNAPSHOT
  userName: http://jt.com
  phone: 123456

3，启动类StudentProviderHystrixApplication_1004加下注解支持 @EnableCircuitBreaker

package com.jt.microservicestudentproviderhystrix1004;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@EnableCircuitBreaker
@EntityScan("com.jt.*.*")
@EnableEurekaClient
@SpringBootApplication
public class MicroserviceStudentProviderHystrix1004Application {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceStudentProviderHystrix1004Application.class, args);
    }

}

4，服务提供者1004中controller新增

package com.jt.microservicestudentproviderhystrix1004.controller;

import com.jt.microservicecommon.entity.Student;
import com.jt.microservicestudentproviderhystrix1004.service.StudentService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/student")
public class StudentProviderController {
 
    @Autowired
    private StudentService studentService;

    @Value("${server.port}")
    private String port;

    @PostMapping(value="/save")
    public boolean save(Student student){
        try{
            studentService.save(student);  
            return true;
        }catch(Exception e){
            return false;
        }
    }
     
    @GetMapping(value="/list")
    public List<Student> list(){
        return studentService.list();
    }
     
    @GetMapping(value="/get/{id}")
    public Student get(@PathVariable("id") Integer id){
        return studentService.findById(id);
    }
     
    @GetMapping(value="/delete/{id}")
    public boolean delete(@PathVariable("id") Integer id){
        try{
            studentService.delete(id);
            return true;
        }catch(Exception e){
            return false;
        }
    }
    @RequestMapping("/ribbon")
    public String ribbon(){
        return "工号【"+port+"】正在为您服务";
    }
    /**
     * 测试Hystrix服务降级
     * @return
     * @throws InterruptedException
     */
    @ResponseBody
    @GetMapping(value="/hystrix")
    @HystrixCommand(fallbackMethod="hystrixFallback")
    public Map<String,Object> hystrix() throws InterruptedException{
        Thread.sleep(2000);
        Map<String,Object> map=new HashMap<String,Object>();
        map.put("code", 200);
        map.put("info","工号【"+port+"】正在为您服务");
        return map;
    }

    public Map<String,Object> hystrixFallback() throws InterruptedException{
        Map<String,Object> map=new HashMap<String,Object>();
        map.put("code", 500);
        map.put("info", "系统【"+port+"】繁忙，稍后重试");
        return map;
    }
}

这里我正常访问返回的是 200 业务数据xxxxx

但是我们这里Thread.sleep(2000) 模拟超时；

这里的话我们加上@HystrixCommand注解以及 fallbackMethod

表明这个方法我们再没有异常以及没有超时(hystrix默认1秒算超时)的情况，才返回正常的业务数据；

否则，进入我们fallback指定的本地方法，我们搞的是500 系统出错，稍后重试，有效的解决雪崩效应，以及返回给用户界面

很好的报错提示信息；

microservice-student-consumer-80项目也要对应的加个方法

package com.jt.microservicestudentconsumer80.controller;

import com.jt.microservicecommon.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/student")
public class StudentConsumerController {

    private final static String SERVER_IP_PORT = "http://MICROSERVICE-STUDENT";
 
     @Autowired
     private RestTemplate restTemplate;
      
     @PostMapping(value="/save")
     private boolean save(Student student){
         return restTemplate.postForObject(SERVER_IP_PORT+"/student/save", student, Boolean.class);
     }
      
    @GetMapping(value="/list")
    public List<Student> list(){
        return restTemplate.getForObject(SERVER_IP_PORT+"/student/list", List.class);
    }
     
    @GetMapping(value="/get/{id}")
    public Student get(@PathVariable("id") Integer id){
        return restTemplate.getForObject(SERVER_IP_PORT+"/student/get/"+id, Student.class);
    }
     
    @GetMapping(value="/delete/{id}")
    public boolean delete(@PathVariable("id") Integer id){
        try{
            restTemplate.getForObject(SERVER_IP_PORT+"/student/delete/"+id, Boolean.class);
            return true;
        }catch(Exception e){
            return false;
        }

    }
    @RequestMapping("/ribbon")
    public String ribbon() {
        return restTemplate.getForObject(SERVER_IP_PORT + "/student/ribbon", String.class);
    }
    /**
     * 测试Hystrix服务降级
     * @return
     */
    @GetMapping(value="/hystrix")
    @ResponseBody
    public Map<String,Object> hystrix(){
        return restTemplate.getForObject(SERVER_IP_PORT+"/student/hystrix/", Map.class);
    }
}

5，然后我们来测试下

先启动三个eureka，再启动带hystrix的provider，最后启动普通的consumer；

Hystrix默认超时时间设置

Hystrix默认超时时间是1秒，我们可以通过hystrix源码看到，

找到 hystrix-core.jar com.netflix.hystrix包下的HystrixCommandProperties类

default_executionTimeoutInMilliseconds属性局势默认的超时时间

我们系统里假如要自定义设置hystrix的默认时间的话；

application.yml配置文件加上

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 3000

Hystrix服务监控Dashboard

Hystrix服务监控Dashboard仪表盘

Hystrix提供了准实时的服务调用监控项目Dashboard，能够实时记录通过Hystrix发起的请求执行情况，

可以通过图表的形式展现给用户看。

我们新建项目：microservice-student-consumer-hystrix-dashboard-90

加依赖：

<!--Hystrix服务监控Dashboard依赖-->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

application.yml配置

server:
  port: 90
  servlet:
    context-path: /

新建启动类：StudentConsumerDashBoardApplication_90

加注解：@EnableHystrixDashboard

package com.jt.microservicestudentconsumerhystrixdashboard90;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;

@SpringBootApplication(exclude={DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
@EnableHystrixDashboard
public class MicroserviceStudentConsumerHystrixDashboard90Application {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceStudentConsumerHystrixDashboard90Application.class, args);
    }

}