實現Hystrix-Dashboard

首先，創建一個新的項目，名稱就是“hystrix-dashboard”，需要加入的依賴有spring-cloud-starter-hystrix，spring-cloud-starter-hystrix-dashboard，spring-cloud-starter-hystrix-actuator，完整的POM文件如下：

<?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">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-parent</artifactId>
		<version>Finchley.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.sc</groupId>
	<artifactId>hystrix-dashboard</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>hystrix-dashboard</name>
	<description>Demo project for Spring Cloud Hystrix dashboard</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-hystrix</artifactId>
			<version>1.4.6.RELEASE</version>
		</dependency>

		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
			<version>1.4.6.RELEASE</version>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
			<version>2.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
			<version>2.1.1.RELEASE</version>
		</dependency>

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

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

在application層面必須注入@EnableHystrixDashboard

package com.sc.hystrixdashboard;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;

@EnableHystrixDashboard
@SpringBootApplication
public class HystrixDashboardApplication {

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

}

運行後，假設開的端口爲8085，應用名稱爲hystrix-dashboard

spring.application.name=hystrix-dashboard
server.port=8085

打開後的效果如下：http://localhost:8085/hystrix

這裏，我們回到對ribbon-consumer的改造，在pom文件里加入依賴：

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

在application.properties加入配置：

management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always
management.endpoint.shutdown.enabled=true

在應用層面註冊HystrixMetricsStreamServlet進入ServletRegistrationBean

package com.sc.consumerribbon;

import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@EnableCircuitBreaker
@SpringBootApplication
@EnableDiscoveryClient
public class ConsumerRibbonApplication {

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

	@Bean
	@LoadBalanced
	public RestTemplate restTemplate(){
		return new RestTemplate();
	}

	@Bean
	public ServletRegistrationBean getServlet() {
		HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
		ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
		registrationBean.setLoadOnStartup(1);
		registrationBean.addUrlMappings("/hystrix.stream");
		registrationBean.setName("HystrixMetricsStreamServlet");
		return registrationBean;
	}
}

重新運行ribbon-consumer，然後在剛纔的Hystrix-Dashboard輸入http://127.0.0.1:9000/hystrix.stream

點擊Monitor Stream，跳到如下界面：

其中，getHello下面的百分比是最近10秒的錯誤率，比如，連續調用10次；

具體含義如下：

實心圓：其有兩種含義。通過顏色的變化代表了實例的健康程度，如下圖所示，它的健康度從綠色、黃色、橙色、紅色遞減。該實心圓除了顏色的變化之外，它的大小也會根據實例的請求流量發生變化，流量越大該實心圓就越大。所以通過該實心圓的展示，我們可以在大量的實例中快速發現故障實例和高壓力實例。

曲線：用來記錄2分鐘內流量的相對變化，可以通過它來觀察流量的上升和下降趨勢。