分布式

Sentinel实现熔断与限流

Sentinel

是什么

Hystrix

下载

https://github.com/alibaba/Sentinel/releases

1598275246796

怎么使用？

https://spring-cloud-alibaba-group.github.io/github-pages/greenwich/spring-cloud-alibaba.html#_spring_cloud_alibaba_sentinel

服务使用中的各种问题

服务雪崩

服务降级

服务熔断

服务限流

安装Sentinel控制台

sentinel组件由2部分组成

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后台

前台8080

安装步骤

下载

https://github.com/alibaba/Sentinel/releases

下载到本地sentinel-dashboard-1.7.0.jar

运行命令

前提:

  • java8环境OK
  • 8080端口不能被占用

命令:

java -jar sentinel-dashboard-1.7.0.jar

访问sentinel管理界面

http://localhost:8080

登录账号密码均为sentinel

初始化演示工程

启动Nacos8848成功

http://localhost:8848/nacos/#/login

Module

cloudalibaba-sentinel-service8401
POM
	<dependencies>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <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>
      
        <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>
YML
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:
        dashboard: localhost:8080
        port: 8719  #默认8719，假如被占用了会自动从8719开始依次+1扫描。直至找到未被占用的端口

management:
  endpoints:
    web:
      exposure:
        include: '*'
主启动
package com.atguigu.springcloud.alibaba;

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


@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}
业务类FlowLimitController
package com.atguigu.springcloud.alibaba.controller;

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

@RestController
public class FlowLimitController
{
    @GetMapping("/testA")
    public String testA() {
        return "------testA";
    }

    @GetMapping("/testB")
    public String testB() {

        return "------testB";
    }
}

启动Sentinel8080

java -jar sentinel-dashboard-1.7.0

启动微服务8401

启动8401微服务后查看sentienl控制台

空空如也，啥都没有

Sentinel采用的懒加载说明

执行一次访问即可

http://localhost:8401/testA

http://localhost:8401/testB

效果

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结论

sentinel8080正在监控微服务8401

流控规则

基本介绍

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进一步解释说明

1598275917235

1598275930554

流控模式

直接（默认）

直接->快速失败
  • 系统默认
配置及说明
1598276075851测试
快速点击访问http://localhost:8401/testA

结果

Blocked by Sentinel (flow limiting)

思考？？？

直接调用默认报错信息，技术方面OK but，是否应该有我们自己的后续处理？

类似有一个fallback的兜底方法？

关联

是什么？

当关联的资源达到阈值时，就限流自己

当与A关联的资源B达到阈值后，就限流自己

B惹事，A挂了

配置A

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postman模拟并发密集访问testB

先把请求save as，保存到Collections

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访问testB成功

  • 1598276623255

postman里新建多线程集合组

  • 1598276640905

将访问地址添加进新线程组

  • 1598276659894

Run

  • 大批量线程高并发访问B，导致A失效了
运行后发现testA挂了

点击访问http://localhost:8401/testA

结果

Blocked by Sentinel (flow limiting)

链路

多个请求调用了同一个微服务

家庭作业试试

流控效果

直接->快速失败（默认的流控处理）

直接失败，抛出异常

  • Blocked by Sentinel (flow limiting)

源码

  • com.alibaba.csp.sentinel.slots.block.flow.controller.DefaultController

预热

说明
  • 公式：阈值除以coldFactor（默认值为3），经过预热时长后才会达到阈值
官网
源码

com.alibaba.csp.sentinel.slots.block.flow.controller.WarmUpController

1598276768339

Warmup配置

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多次点击http://localhost:8401/testB
  • 刚开始不行，后续慢慢OK
应用场景

1598277148535

排队等待

1598276768339

匀速排队，阈值必须设置为QPS
官网
源码

com.alibaba.csp.sentinel.slots.block.flow.controller.RateLimiterController

测试

testB在控制台输出日志sl4j

log.info(thread.currentThread.getName()+"\t"+"...testB")

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降级规则

基本介绍

1598277395163

1598277412123

进一步说明

Sentinel的断路器是没有半开状态的

半开的状态系统自动去检测是否请求有异常，没有异常就关闭断路器恢复使用，有异常则继续打开断路器不可用。具体可以参考Hystrix

复习Hystrix

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1598277592247

降级策略实战

RT

是什么?

1598277795422

1598277815933

测试

代码

    @GetMapping("/testD")
    public String testD()
    {
        try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
        log.info("testD 测试RT");

        return "------testD";
    }

配置

1598277885759

jmeter压测

结论

1598277904111

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异常比例

是什么

1598277953235

1598277965489

测试

  • 代码

    @GetMapping("/testD")
    public String testD()
    {

        log.info("testD 测试RT");
        int age = 10/0;
        return "------testD";
    }

  • 配置

    1598278071559

  • jmeter

    1598278103683

  • 结论

    1598278121021

异常数

是什么

1598278157875

1598278172535

异常数是按照分钟统计的

测试

  • 代码
@GetMapping("/testE")
public String testE()
{
    log.info("testE 测试异常数");
    int age = 10/0;
    return "------testE 测试异常数";
}
  • 配置

http://localhost:8401/testE

1598278242551

  • jmeter

热点key限流

基本介绍

是什么

1598281015660

https://github.com/alibaba/Sentinel/wiki/热点参数限流

承上启下复习start

1598281047415

@SentinelResource

代码

@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false) String p1,
                         @RequestParam(value = "p2",required = false) String p2) {
    //int age = 10/0;
    return "------testHotKey";
}
 
//兜底方法
public String deal_testHotKey (String p1, String p2, BlockException exception){
    return "------deal_testHotKey,o(╥﹏╥)o";  
}

com.alibaba.csp.sentinel.slots.block.BlockException

配置

配置

1598281119051

1

@SentinelResource(value = “testHotKey”)

异常打到了前台用户界面看不到，不友好

2

@SentinelResource(value = “testHotKey”,blockHandler = “deal_testHotKey”)

方法testHostKey里面第一个参数只要QPS超过每秒1次，马上降级处理

用了我们自己定义的

测试

:x: error

http://localhost:8401/testHotKey?p1=abc

:x: error

http://localhost:8401/testHotKey?p1=abc&p2=33

:heavy_check_mark: right

http://localhost:8401/testHotKey?p2=abc

参数例外项

上述案例演示了第一个参数p1,当QPS超过1秒1次点击后马上被限流

特殊情况

普通

  • 超过1秒钟一个后，达到阈值1后马上被限流

我们期望p1参数当它是某个特殊值时，它的限流值和平时不一样

特例

  • 假如当p1的值等于5时，它的阈值可以达到200

配置

1598281694486

1598281694486

  • 添加按钮不能忘
测试

:heavy_check_mark: http://localhost:8401/testHotKey?p1=5

:x:http://localhost:8401/testHotKey?p1=3

当p1等于5的时候，阈值变为200

当p1不等于5的时候，阈值就是平常的1

前提条件

热点参数的注意点，参数必须是基本类型或者String

其他,

添加异常看看….

1598281913264

系统规则

是什么？

https://github.com/alibaba/Sentinel/wiki/%E7%B3%BB%E7%BB%9F%E8%87%AA%E9%80%82%E5%BA%94%E9%99%90%E6%B5%81

各项配置参数说明

1598337022929

配置全局QPS

@SentinelResource

按资源名称限流+后续处理

启动Nacos成功

启动Sentinel成功

Module

cloudalibaba-sentinel-service8401

POM

<dependency>
    <groupId>com.atguigu.springcloud</groupId>
    <artifactId>cloud-api-commons</artifactId>
    <version>${project.version}</version>
</dependency>

yml

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719  #默认8719，假如被占用了会自动从8719开始依次+1扫描。直至找到未被占用的端口

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

业务类RateLimitController

package com.atguigu.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;

import com.atguigu.springcloud.entities.*;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class RateLimitController
{
    @GetMapping("/byResource")
    @SentinelResource(value = "byResource",blockHandler = "handleException")
    public CommonResult byResource()
    {
        return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
    }
    public CommonResult handleException(BlockException exception)
    {
        return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
    }

主启动

package com.atguigu.springcloud.alibaba;

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


@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }

}

配置流控规则

  • 配置步骤

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  • 图形配置和代码关系
  • 表示1秒钟内查询次数大于1，就跑到我们自定义的处流，限流

测试

  • 1秒钟点击1下，OK

  • 超过上述问题，疯狂点击，返回了自己定义的限流处理信息，限流发送

    1598337235793

额外问题

  • 此时关闭微服务8401看看

  • Sentinel控制台，流控规则消失了？？

    临时/持久？

按照Url地址限流+后续处理

通过访问的URL来限流，会返回Sentinel自带默认的限流处理信息

业务类RateLimitController

@GetMapping("/rateLimit/byUrl")
@SentinelResource(value = "byUrl")
public CommonResult byUrl()
{
    return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));
}

访问一次

Sentinel控制台配置

1598337354555

测试

  • 疯狂点击http://localhost:8401/rateLimit/byUrl

  • 1598337380401

上面兜底方法面临的问题

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客户自定义限流处理逻辑

创建customerBlockHandler类用于自定义限流处理逻辑

自定义限流处理类

  • CustomerBlockHandler

    1598337444808

package com.atguigu.springcloud.alibaba.myhandler;

import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.entities.*;

public class CustomerBlockHandler {

    public static CommonResult handleException(BlockException exception) {
        return new CommonResult(2020, "自定义限流处理信息....CustomerBlockHandler");

    }
}

RateLimitController

@GetMapping("/rateLimit/customerBlockHandler")
@SentinelResource(value = "customerBlockHandler",
        blockHandlerClass = CustomerBlockHandler.class,
        blockHandler = "handlerException2")
public CommonResult customerBlockHandler()
{
    return new CommonResult(200,"按客戶自定义",new Payment(2020L,"serial003"));
}

启动微服务后先调用一次

http://localhost:8401/rateLimit/customerBlockHandler

Sentinel控制台配置

测试后我们自定义的出来了

进一步说明:

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更多注解属性说明

1598337561019

1598337573475

多说一句

1598337587461

Sentinel主要有三个核心API

  • SphU定义资源

  • Tracer定义统计

  • ContextUtil定义了上下文

服务熔断功能

sentinel整合ribbon+openFeign+fallback

Ribbon系列

启动nacos和sentinel

提供者9003/9004

新建cloudalibaba-provider-payment9003/9004

POM

<dependencies>
    <!--SpringCloud ailibaba nacos -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
    <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <groupId>com.atguigu.springcloud</groupId>
        <artifactId>cloud-api-commons</artifactId>
        <version>${project.version}</version>
    </dependency>
    <!-- SpringBoot整合Web组件 -->
    <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>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>

yml

server:
  port: 9003

spring:
  application:
    name: nacos-payment-provider
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #配置Nacos地址

management:
  endpoints:
    web:
      exposure:
        include: '*'
  • 记得修改不同的端口号

主启动

package com.atguigu.springcloud.alibaba;

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


@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain9003
{
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain9003.class, args);
    }
}

业务类

package com.atguigu.springcloud.alibaba.controller;

import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;

@RestController
public class PaymentController
{
    @Value("${server.port}")
    private String serverPort;

    public static HashMap<Long, Payment> hashMap = new HashMap<>();
    static{
        hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181"));
        hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182"));
        hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183"));
    }

    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id){
        Payment payment = hashMap.get(id);
        CommonResult<Payment> result = new CommonResult(200,"from mysql,serverPort:  "+serverPort,payment);
        return result;
    }
}

测试地址

http://localhost:9003/paymentSQL/1

消费者84

新建cloudalibaba-consumer-nacos-order84

POM

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <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>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </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>

YML

server:
  port: 84


spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719

service-url:
  nacos-user-service: http://nacos-payment-provider

主启动

package com.atguigu.springcloud.alibaba;

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


@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

业务类

ApplicationContextConfig

package com.atguigu.springcloud.alibaba.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;


@Configuration
public class ApplicationContextConfig
{
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate()
    {
        return new RestTemplate();
    }
}

CircleBreakerController的全部源码

package com.atguigu.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;


@RestController
@Slf4j
public class CircleBreakerController {
   
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
    //@SentinelResource(value = "fallback") //没有配置
    //@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责业务异常
    //@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规
    @SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler",
            exceptionsToIgnore = {IllegalArgumentException.class})
    public CommonResult<Payment> fallback(@PathVariable Long id) {
        CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id, CommonResult.class,id);

        if (id == 4) {
            throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
        }else if (result.getData() == null) {
            throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
        }

        return result;
    }
  
    //fallback
    public CommonResult handlerFallback(@PathVariable  Long id,Throwable e) {
        Payment payment = new Payment(id,"null");
        return new CommonResult<>(444,"兜底异常handlerFallback,exception内容  "+e.getMessage(),payment);
    }
  
    //blockHandler
    public CommonResult blockHandler(@PathVariable  Long id,BlockException blockException) {
        Payment payment = new Payment(id,"null");
        return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException  "+blockException.getMessage(),payment);
    }
}

修改后请重启微服务

  • 热部署对java代码级生效及时
  • 对@SentinelResource注解内属性，有时效果不好

目的

  • fallback管运行异常
  • blockHandler管配置违规

测试地址

  • http://localhost:84/consumer/fallback/1

没有任何配置

  • 给客户error页面，不友好

只配置fallback

  • 编码（那个业务类下面的CircleBreakerController的全部源码）

只配置blockHandler

  • 编码（那个业务类下面的CircleBreakerController的全部源码）

fallback和blockHandler都配置

  • 结果

    1598338239282

忽略属性…

  • 编码（那个业务类下面的CircleBreakerController的全部源码）

    1598338281914

Feign系列

修改84模块

POM

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

yml

server:
  port: 84


spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719

service-url:
  nacos-user-service: http://nacos-payment-provider

#对Feign的支持
feign:
  sentinel:
    enabled: true

业务类

  • 带@FeignClient注解的业务接口

    package com.atguigu.springcloud.alibaba.service;


import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;


@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)
public interface PaymentService
{
    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id);
}

  • fallback = PaymentFallbackService.class

  • PaymentFallbackService实现类

    package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;
import org.springframework.stereotype.Component;

@Component
public class PaymentFallbackService implements PaymentService
{
    @Override
    public CommonResult<Payment> paymentSQL(Long id)
    {
        return new CommonResult<>(44444,"服务降级返回,---PaymentFallbackService",new Payment(id,"errorSerial"));
    }
}

  • Controller

    // OpenFeign
@Resource
private PaymentService paymentService;

@GetMapping(value = "/consumer/paymentSQL/{id}")
public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id) {
    return paymentService.paymentSQL(id);
}

主启动

添加@EnableFeignClients启动Feign的功能

package com.atguigu.springcloud.alibaba;

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

@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

http://lcoalhost:84/consumer/openfeign/1

http://lcoalhost:84/consumer/paymentSQL/1

测试84调用9003，此时故意关闭9003微服务提供者，看84消费侧自动降级，不会被耗死

熔断框架比较

1598339929387

1598339942749

规则持久化

是什么

一旦我们重启应用，Sentinel规则将消失，生产环境需要将配置规则进行持久化

怎么玩

将限流配置规则持久化进Nacos保存，只要刷新8401某个rest地址，sentinel控制台的流控规则就能看到，只要Nacos里面的配置不删除，针对8401上Sentinel上的流控规则持续有效

步骤

修改cloudalibaba-sentinel-service8401

POM

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-nacos</artifactId>
</dependency>

YML

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #Nacos服务注册中心地址
    sentinel:
      transport:
        dashboard: localhost:8080 #配置Sentinel dashboard地址
        port: 8719
      datasource:
        ds1:
          nacos:
            server-addr: localhost:8848
            dataId: cloudalibaba-sentinel-service
            groupId: DEFAULT_GROUP
            data-type: json
            rule-type: flow

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

feign:
  sentinel:
    enabled: true # 激活Sentinel对Feign的支持

添加Nacos数据源配置

spring:
   cloud:
    sentinel:
    datasource:
     ds1:
      nacos:
        server-addr:localhost:8848
        dataid:${spring.application.name}
        groupid:DEFAULT_GROUP
        data-type:json
            rule-type:flow

添加Nacos业务规则配置

1598340101146

1598340112967

内容解析

[
    {
         "resource": "/retaLimit/byUrl",
         "limitApp": "default",
         "grade":   1,
         "count":   1,
         "strategy": 0,
         "controlBehavior": 0,
         "clusterMode": false    
    }
]

1598340151536

启动8401后刷新sentinel发现业务规则有了

1598340340265

快速访问测试接口

  • http://localhost:8401/rateLimit/byUrl

  • 默认

    图像

停止8401再看sentinel

1598340454693

重新启动8401再看sentinel:

扎一看还是没有，稍等一会儿

多次调用

http://localhost:8401/rateLimit/byUrl

重新配置出现了，持久化验证通过

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