SpringCloud Alibaba Sentinel实现熔断与限流

1、Sentinel的介绍

随着微服务的流行，服务和服务之间的稳定性变得越来越重要。Sentinel 是面向分布式、多语言异构化服务架构的流量治理组件，主要以流量为切入点，从流量路由、流量控制、流量整形、熔断降级、系统自适应过载保护、热点流量防护等多个维度来帮助开发者保障微服务的稳定性。

2、下载Sentinel和运行

在存放下载的Sentitneljar包位置通过如下命令进行启迪

java -jar sentinel-dashboard-1.8.5.jar

页面访问本机地址的8080端口

需要保证本机的8080端口不被占用

3、初始化演示工程

3.1、启动Nacos8848（win版）

win单节点启动命令

startup.cmd -m standalone

浏览器访问：http://192.168.26.1:8848/nacos/index.html

3.2、创建cloudalibaba-sentinel-service8401模块

3.2.1、添加pom.xml依赖

以后使用阿里巴巴cloud的都使用前三个依赖

<dependencies>
    <!--SpringCloud ailibaba nacos -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
    <!--SpringCloud ailibaba sentinel-datasource-nacos 后续做持久化用到-->
    <dependency>
        <groupId>com.alibaba.csp</groupId>
        <artifactId>sentinel-datasource-nacos</artifactId>
    </dependency>
    <!--SpringCloud ailibaba sentinel -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    </dependency>
    <!--openfeign-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <!-- SpringBoot整合Web组件+actuator -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <!--日常通用jar包配置-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>cn.hutool</groupId>
        <artifactId>hutool-all</artifactId>
        <version>4.6.3</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

</dependencies>

3.2.2、配置YAML文件

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        #Nacos服务注册中心地址
        server-addr: localhost:8848
    sentinel:
      transport:
        #配置Sentinel dashboard地址，8080监控8401
        dashboard: localhost:8080
        #默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
        port: 8719

# 图像化展示，暴露所有端口
management:
  endpoints:
    web:
      exposure:
        include: '*'

3.2.3、添加主启动类

package com.zcl.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * 描述：哨兵启动类
 *
 * @author zhong
 * @date 2022-09-27 22:06
 */
@SpringBootApplication
@EnableDiscoveryClient
public class MainApp8401 {
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}

3.2.4、添加业务控制器接口

package com.zcl.springcloud.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 描述：流控哨兵控制器接口
 *
 * @author zhong
 * @date 2022-09-27 22:07
 */
@RestController
public class FlowLimitController {
    @GetMapping("/testA")
    public String testA()
    {
        return "------testA";
    }

    @GetMapping("/testB")
    public String testB()
    {
        return "------testB";
    }
}

3.2.5、启动项目

3.3、启动Sentinel哨兵

java -jar sentinel-dashboard-1.8.5.jar

Sentinel是懒加载，上面的8401项目已经是跑起来了的，但是直接访问Sentinl是看不到具体的监控服务信息的，需要给服务发送一些请求

http://localhost:8401/testA

http://localhost:8401/testB

访问如上接口后再次查看Sentinel的监控页面