1. 簡介

Hystrix是Netflix解決自己業務不穩定性的一個限流容錯框架，可以幫助我們解決微服務架構體系中的限流、降級、熔斷等功能。提高系統穩定性，提供了完善的監控實現，並且Hystrix可以根據監控資料動態調整內部處理機制。

Hystrix Dashboard提供了數字與圖形化的呼叫監控情況。

2. 程式碼實現

2.1 涉及的模組及整體步驟

2.1.1 涉及的模組

• eureka-server-singleton：微服務的服務註冊中心，限流熔斷針對的是服務呼叫異常的處理。
• eureka-hystrix-dashboard：圖形化展示資料監控情況

2.1.2 整體步驟

2. 實現eureka-server-singleton
3. 實現eureka-hystrix-dashboard
4. 呼叫eureka-hystrix-dashboard提供的服務介面
5. 開啟eureka-hystrix-dashboard的監控介面，輸入相關資訊，檢視呼叫情況

2.2 原始碼

2.2.1 Github地址

2.3 eureka-server-singleton

2.4 eureka-hystrix-dashboard

2.4.1 整體實現

1. pom.xml：引入相關依賴，具體檢視下方具體程式碼
2. application.yml：指定埠，應用名，註冊中心訪問地址資訊
3. bootstrap.yml：指定公開SpringBoot的actuator監控端點為所有
4. EurekaHystrixDashboardApplication：Spring boot啟動類，提供一個簡單的REST服務介面

2.4.2 pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"
 
>
    <parent>
        <artifactId>spring-cloud-finchley-demo</artifactId>
        <groupId>org.oscar.scd</groupId>
        <version>1.0.0</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>eureka-hystrix-dashboard</artifactId>

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

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

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-hystrix-dashboard -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
            <version>1.4.5.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-hystrix -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
            <version>1.4.5.RELEASE</version>
        </dependency>
    </dependencies>
</project>

2.4.3 application.yml

server:
  port: 8785

spring:
  application:
    name: eureka-hystrix-dashboard

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

2.4.4 bootstrap.yml

management:
  endpoints:
    web:
      exposure:
        include: '*'

2.4.5 EurekaHystrixDashboardApplication

package org.oscar.scd.eureka.hystrix.dashboard;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@EnableHystrix
@RestController
@EnableEurekaClient
@EnableCircuitBreaker
@EnableDiscoveryClient
@SpringBootApplication
@EnableHystrixDashboard
public class EurekaHystrixDashboardApplication {

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

    @Value("${spring.application.name}")
    private String appName;

    @RequestMapping("/appName")
    @HystrixCommand(fallbackMethod = "errorMsg")
    public String getAppName() {
        return this.appName;
    }

    @SuppressWarnings("unused")
    public String errorMsg() {
        return "Error msg by hystrix.";
    }
}

3. 驗證

3.1 建立SpringBoot啟動類

最簡單的方式新增一個SpringBoot啟動型別的啟動類就行，如果對SpringBoot有所瞭解或者看過前面系列的文章，這裡很簡單。

3.1.1 EurekaServerSingletonApplication

略

3.1.2 EurekaHystrixDashboardApplication

略

3.2 啟動

1. EurekaServerSingletonApplication
2. EurekaHystrixDashboardApplication

3.3 檢視Hystrix Dashboard

eureka-hystrix-dashboard

3. 訪問Hystrix介面前兩個輸入框依次輸入：http://localhost:8785/actuator/hystrix.stream、2000

4. 思考

• 現在的僅限於單機監控，如何在分散式環境下檢視監控資訊
• 如何與呼叫鏈監控整合，也就是如何搭建一個完整的監控平臺
• 現在這個要輸入查詢條件，如何定製化首介面和展示項，更接近於實用和生產

5. 補充

5.1 資料