SpringCloud Alibaba Sentinel 实现熔断功能

快乐的小三菊2024-04-12 19:30

一、前言

接下来是开展一系列的 SpringCloud 的学习之旅，从传统的模块之间调用，一步步的升级为 SpringCloud 模块之间的调用，此篇文章为第十六篇，即使用 Sentinel实现熔断功能。

二、 Ribbon 系列

首先我们新建两个服务的提供者模块 cloudalibaba-provider-payment9003 和cloudalibaba-provider-payment9004 ，这两个模块除了配置文件里面的端口号和主启动类不一样，其他的都一样，我这里只介绍其中一个模块的创建过程，pom.xml内容如下：

XML 复制代码 
<?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>com.springcloud</groupId>
        <artifactId>SpringCloud</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>cloudalibaba-provider-payment9003</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <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.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>
</project>

application.yml内容如下所示：

ruby 复制代码 
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: '*'

主启动类代码如下：

java 复制代码 
package com.springcloud;

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);
    }
}

对外提供的 controller代码如下：

java 复制代码 
package com.springcloud.controller;

import com.springcloud.entities.CommonResult;
import com.springcloud.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;
    }
}

创建一个服务的消费者模块cloudalibaba-consumer-nacos-order84 ，pom.xml内容如下所示：

XML 复制代码 
<?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>com.springcloud</groupId>
        <artifactId>SpringCloud</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>cloudalibaba-consumer-nacos-order84</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!--SpringCloud openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--SpringCloud ailibaba nacos -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--SpringCloud ailibaba sentinel -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>com.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>
</project>

application.yml代码如下所示：

ruby 复制代码 
server:
  port: 84


spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        #配置Sentinel dashboard地址
        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

#消费者将要去访问的微服务名称(注册成功进nacos的微服务提供者)
service-url:
  nacos-user-service: http://nacos-payment-provider

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

主启动类代码如下：

java 复制代码 
package com.springcloud;

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);
    }
}

配置类代码如下，使其支持负载均衡

java 复制代码 
package com.springcloud.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();
    }
}

业务类 controller代码如下：

java 复制代码 
@Slf4j
@RestController
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
        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;
        }
}

分别启动两个服务提供者和一个消费者，启动完成后，访问 http://localhost:84/consumer/fallback/1，进行测试，多刷新几次，可以看到，服务之间的调用没有任何问题，且负载均衡好用。

当我们访问第四条和第五条数据时，由于我们人为的配置了抛出异常，给用户展示了 error 的界面，效果并不是很好，如下图：

2.1 只配置 fallback

为了解决上面返回给客户不友好的界面，我们可以配置 fallback 属性来解决这个问题，它可以对业务的异常进行兜底，修改 CircleBreakerController 类，加上 fallback属性和其对应的方法，如下：

java 复制代码 
@Slf4j
@RestController
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
    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;
    }

    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);
    }
}

重启模块，当我们再次访问第四条和第五条数据时，效果就很好了，如下图：

2.2 只配置 blockHandler

修改 CircleBreakerController 类，加上 blockHandler属性和其对应的方法，如下：

java 复制代码 
@Slf4j
@RestController
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
    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;
    }

    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);
    }
}

配置完毕后打开 sentinel的管理界面配置降级规则，如下：

在浏览器访问 http://localhost:84/consumer/fallback/4，如果点击一次，返回的还是 java的运行时异常信息，如下图：

如果多点击几次，则显示的是 blockHandler指定的返回信息，如下图：

2.3 配置 fallback 和 blockHandler

若既配置了 fallback ，又配置了 blockHandler ，又会出现什么效果呢？修改 CircleBreakerController类，代码如下：

java 复制代码 
@Slf4j
@RestController
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")
    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;
    }

    // 本例是 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);
    }
    // 本例是 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);
    }
}

在 sentinel中配置一个限流规则，如下：

在浏览器访问 http://localhost:84/consumer/fallback/1，如果点击一次，返回结果如下：

频繁点击，效果如下，可以看到限流效果出现了。

在浏览器访问 http://localhost:84/consumer/fallback/4，点击一次，返回结果如下，是 fallback 生效了。

频繁点击，效果如下，可以看到限流效果出现了。

2.4 结论

若 blockHandler 和 fallback 都进行了配置，则被限流降级而抛出 BlockException 时只会进入 blockHandler处理逻辑。

2.5 忽略属性

假如我有一个异常，我不想让 fallback 方法帮我兜底，我就可以通过配置 exceptionsToIgnore 属性来实现，修改 CircleBreakerController 类的代码，添加 exceptionsToIgnore属性，如下：

java 复制代码 
@Slf4j
@RestController
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;
    }

    // 本例是 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);
    }
    // 本例是 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);
    }
}

在 sentinel中配置降级规则，如下图：

在浏览器中访问 http://localhost:84/consumer/fallback/4，如下图，可以发现，fallback方法并没有生效，但是限流方法方法生效了

三、Feign 系列

3.1 maven 依赖

首先确保消费者模块cloudalibaba-consumer-nacos-order84 的pom.xml 中引入了 openFegin 的依赖，如下：

XML 复制代码 
<!--SpringCloud openfeign -->
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

3.2 修改配置文件

接下来需要在 application.yml 中激活 sentinel 对 Feign的支持，如下：

3.3 相关业务类

编写带有 @FeignClient注解的业务接口，如下：

java 复制代码 
package com.springcloud.service;


import com.springcloud.entities.CommonResult;
import com.springcloud.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);
}

然后编写 fallback参数指定的的兜底方法的类，代码如下：

java 复制代码 
package com.springcloud.service;

import com.springcloud.entities.CommonResult;
import com.springcloud.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"));
    }
}

修改 CircleBreakerController类，在里面添加如下的方法：

java 复制代码 
    @Resource
    private PaymentService paymentService;

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

不要忘了在启动类上添加启用 Feign的注解，如下图：

3.4 测试

分别启动 cloudalibaba-provider-payment9003 模块和 cloudalibaba-consumer-nacos-order84 模块，在浏览器输入：http://localhost:84/consumer/paymentSQL/1，如下图，可以正常的访问：

此时故意关闭 9003 微服务提供者，看 84消费侧自动降级，会不会被耗死，如下图，可以看到，自动进入到了我们指定的兜底方法里面了。

四、熔断框架比较

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