SpringCloud（20）：Sentinel：Feign实现服务降级、Sentinel规则持久化

迷南。 2022-10-25 01:23 211阅读 0赞

### 一、准备工作 ###

需要启动Nacos和Sentinel。

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![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 1][]

### 二、服务消费者 ###

（1）添加依赖

<?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>springcloud</artifactId>
            <groupId>com.buba</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>consumer-80</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework.cloud</groupId>
                        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
                    </exclusion>
                </exclusions>
            </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>
                <version>3.0.0</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.cloud</groupId>
                <artifactId>spring-cloud-loadbalancer</artifactId>
            </dependency>
        </dependencies>
    </project>

（2）业务逻辑代码

package com.buba.springcloud.feign;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    
    @FeignClient(value = "provider", fallback = PaymentFeignCallback.class)
    public interface PaymentFeign {
    
        @GetMapping(value = "/provider/get/{id}")
        String payment(@PathVariable(value = "id") Integer id);
    
    }

package com.buba.springcloud.feign;
    
    import org.springframework.stereotype.Component;
    
    @Component
    public class PaymentFeignCallback implements PaymentFeign {
        @Override
        public String payment(Integer id) {
            return "熔断降级";
        }
    }

package com.buba.springcloud.controller;
    
    import com.buba.springcloud.feign.PaymentFeign;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RestController;
    
    import javax.annotation.Resource;
    
    @RestController
    public class HelloController {
    
        private PaymentFeign paymentFeign;
    
        @GetMapping(value = "/order/{id}")
        public String order(@PathVariable(value = "id") Integer id) {
            return this.paymentFeign.payment(id);
        }
    
        @Resource
        public void setPaymentFeign(PaymentFeign paymentFeign) {
            this.paymentFeign = paymentFeign;
        }
    }

（3）启动类

package com.buba.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;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients
    public class Consumer_80 {
        public static void main(String[] args) {
            SpringApplication.run(Consumer_80.class, args);
        }
    }

（4）启动测试

访问地址：[http://localhost/order/1][http_localhost_order_1]

![20210130162335687.png][]

### 三、Sentinel规则持久化 ###

（1）为什么持久化

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。将Sentinel中的规则持久化到Nacos保存，只要Nacos里面的配置不删除，那么Sentinel中的规则将持续有效。

（2）添加依赖（修改服务消费者）

<?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>springcloud</artifactId>
            <groupId>com.buba</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>consumer-80</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework.cloud</groupId>
                        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            </dependency>
            
            <dependency>
                <groupId>com.alibaba.csp</groupId>
                <artifactId>sentinel-datasource-nacos</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
                <version>3.0.0</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.cloud</groupId>
                <artifactId>spring-cloud-loadbalancer</artifactId>
            </dependency>
        </dependencies>
    </project>

（3）修改application.yml

server:
      port: 80
    spring:
      application:
        name: consumer
      cloud:
        # nocos注册中心
        nacos:
          discovery:
            server-addr: localhost:8848
        sentinel:
          transport:
            # 配置Sentinel Dashboard地址
            dashboard: 127.0.0.1:8080
            # 默认8719端口，假设被占用会自动从8719开始依次加1扫描，直到找到没有被占用的端口
            port: 8719
              # 将Sentinel的规则持久化到Nacos中
          datasource:
            ds1:
              nacos:
                server-addr: 127.0.0.1:8848
                dataId: ${spring.application.name}
                groupId: DEFAULT_GROUP
                data_type: json
                rule_type: flow
          # 取消懒加载
          eager: true
    
        
    management:
      endpoints:
        web:
          exposure:
            include: '*'

（4）在Nacos中添加业务规则配置

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 2][]

[
        {
            "resource": "/hello", 
            "limitApp": "default", 
            "grade": 1, 
            "count": 5, 
            "strategy": 0, 
            "controlBehavior": 0, 
            "clusterMode": false 
        }
    ]

*  resource：资源名称。
 *  limitApp：来源应用。
 *  grade：阈值类型，0表示线程数，1表示QPS。
 *  count：单机阈值。
 *  strategy：流控模式，0表示直接，1表示关联，2表示链路。
 *  controlBehavior：流控效果，0表示快速失败，1表示Warm up，2表示排队等待。
 *  clusterMode：是否集群。

（5）启动微服务消费者，刷新Sentinel

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 3][]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 1]: /images/20221024/f63e8022d2ed4db9a5c653fc6866ac34.png
[http_localhost_order_1]: http://localhost/order/1
[20210130162335687.png]: /images/20221024/f04b20f0fc3f4e1b85e6a213cd667a0f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 2]: /images/20221024/e3dd5f8d92c24c4c8add59cdb2b5a1a5.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 3]: /images/20221024/bc6e7415b09a4eddb20784352ce07a02.png