SpringCloud Alibaba_Sentinel实现熔断与限流

青旅半醒 2023-05-22 05:59 55阅读 0赞

### 文章目录 ###

*  安装Sentinel
 *   *  下载
     *  运行命令
     *  访问sentinel管理界面
 *  流控规则
 *   *  基本介绍
 *  降级规则
 *   *  RT
     *  异常比例
     *  异常数
 *  热点key限流
 *   *  配置
     *  参数例外项
 *  系统规则
 *  @SentinelResource
 *   *  按照资源名称+流控规则限流+后续处理
     *  按照url+流控规则限流+后续处理
     *  现阶段问题
     *  自定义限流处理逻辑
 *  服务熔断
 *   *  消费侧Sentinel整合Ribbon+OpenFeign+FallBack
     *   *  Ribbon
         *  OpenFeign
 *  规则持久化

# 安装Sentinel #

sentinel组件由两个部分组成：

*  核心库（Java客户端），不依赖任何框架和库，能够运行于Java运行时环境，同时对SpringCloud等框架也有较好的支持。
 *  控制台（DashBoard）基于SpringBoot开发，打包后可以直接运行，不需要额外的Tomcat等应用容器

## 下载 ##

[https://github.com/alibaba/Sentinel/releases][https_github.com_alibaba_Sentinel_releases]

## 运行命令 ##

java -jar sentinel-dashboard-1.7.2.jar

注意：8080端口不能被占用

## 访问sentinel管理界面 ##

[http://localhost:8080][http_localhost_8080]  
账号密码：`sentinel`

# 流控规则 #

## 基本介绍 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70]

*  资源名：唯一名称，默认请求路径
 *  针对来源：Sentinel可以针对调用者进行限流，填写微服务名，默认default（不区分来源）
 *  阈值类型/单机阈值
    
     *  QPS（每秒请求数量）：当调用该api的QPS达到阈值的时候，进行限流
     *  线程数：当调用该api的线程数达到阈值的时候，进行限流
 *  是否集群：不需要集群
 *  流控模式：
    
     *  直接：api达到限流条件时，直接限流  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 1]
     *  关联：当关联的资源达到阈值时，就限流自己  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 2]
     *  链路：只记录指定链路上的流量（指定资源从入口资源进来的流量，如果达到阈值，就进行限流）
 *  流控效果
    
     *  快速失败：直接失败。抛异常
     *  Warm up：根据coldfactor（冷加载因子，默认3）的值，从阈值/coldfactor，经过预热时长，才达到设置的QPS阈值  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 3]  
        如：秒杀系统在开启瞬间，会有很多流量上来，很可能把系统打死，预热方式就是为了保护系统，可慢慢的把流量放进来，慢慢的把阈值增长到设置的阈值。
     *  排队等待：匀速排队，让请求以匀速通过，阈值类型必须设置为QPS，否则无效  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 4]  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 5]

# 降级规则 #

## RT ##

![在这里插入图片描述][20200416141826662.png]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 6]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 7]

## 异常比例 ##

![在这里插入图片描述][2020041614194640.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 8]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 9]

## 异常数 ##

![在这里插入图片描述][2020041614220315.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 10]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 11]

# 热点key限流 #

## 配置 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 12]

@GetMapping("/testHotKey")
    @SentinelResource(value = "testHotKey")
    public String testHotKey(@RequestParam(value = "p1",required = false) String p1,
                             @RequestParam(value = "p2",required = false) String p2)
    {
        
        //int age = 10/0;
        return "------testHotKey";
    }

返回异常不友好界面，blocked by sentinel

@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";
    }
    public String deal_testHotKey (String p1, String p2, BlockException exception)
    {
        
        return "------deal_testHotKey,o(╥﹏╥)o";  //sentinel系统默认的提示：Blocked by Sentinel (flow limiting)
        }

自定义blockHandler，处理异常。

## 参数例外项 ##

假如当p1的值等于5时，它的阈值可以达到200：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 13]  
**参数类型仅限于基本数据类型或者String**

# 系统规则 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 14]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 15]  
系统配置管辖太宽泛，可能引起全局范围内的问题，不使用，危险。

# @SentinelResource #

## 按照资源名称+流控规则限流+后续处理 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 16]

@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");
    }

## 按照url+流控规则限流+后续处理 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 17]

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

## 现阶段问题 ##

*  系统默认，没有体现特定的业务要求
 *  自定义Handler与业务逻辑耦合
 *  每个业务逻辑都需要独自的兜底Handler，代码膨胀
 *  没有全局统一的处理方法

## 自定义限流处理逻辑 ##

*  自定义限流处理类

public class CustomerBlockHandler
    {
        
        public static CommonResult handlerException(BlockException exception)
        {
        
            return new CommonResult(4444,"按客戶自定义,global handlerException----1");
        }
        public static CommonResult handlerException2(BlockException exception)
        {
        
            return new CommonResult(4444,"按客戶自定义,global handlerException----2");
        }
    }

*  修改@SentinelResource

@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"));
    }

# 服务熔断 #

## 消费侧Sentinel整合Ribbon+OpenFeign+FallBack ##

*  pom

<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>

*  yml

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

### Ribbon ###

*  配置RestTemplate

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

*  业务逻辑

@RequestMapping("/consumer/fallback/{id}")
    //fallback只负责业务异常
    //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);
    }

### OpenFeign ###

*  Service

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

*  FallBackService

@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

@Resource
    private PaymentService paymentService;
    
    @GetMapping(value = "/consumer/paymentSQL/{id}")
    @SentinelResource(value = "fallback",blockHandler = "blockHandler")
    public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id)
    {
        
        return paymentService.paymentSQL(id);
    }

# 规则持久化 #

一旦重启应用,sentinel规则消失,生产环境需要将配置规则进行持久化。  
将限流规则持久进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得到,只要Nacos里面的配置不删除,针对8401上的流控规则持续有效

*  pom

<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>

*  yaml

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业务规则配置  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 18]  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 19]  
    ![在这里插入图片描述][20200514194844570.png]

[https_github.com_alibaba_Sentinel_releases]: https://github.com/alibaba/Sentinel/releases
[http_localhost_8080]: http://localhost:8080
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70]: /images/20230521/48a2378316cc429bab99ae27e11b7592.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 1]: /images/20230521/e7cb91ca80574cbe98fce67a145e614a.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 2]: /images/20230521/568a432ee66d4a09a13f8b5626c323d1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 3]: /images/20230521/7042b78eff434b969ca62ace5b40ef4c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 4]: /images/20230521/8277d14ceff54d7183d2c4c6e6537f2b.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 5]: /images/20230521/33882a488f1d493bae54a6592ffb61e1.png
[20200416141826662.png]: /images/20230521/0a757cf50f424ae08a1cc9a50fcd3c81.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 6]: /images/20230521/989cc615f0fe43a4bdb1d5890db9edfd.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 7]: /images/20230521/6145c675107d4a069894f54452cdbd09.png
[2020041614194640.png]: /images/20230521/450d5e4acd704075a85ad12848009246.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 8]: /images/20230521/9fd06bc6d0974449aa5762bc4c2fc146.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 9]: /images/20230521/73aad8cfa1d44c5ebf6365580458c543.png
[2020041614220315.png]: /images/20230521/1f01cc9eebfe49ea87d21d654e4fadf7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 10]: /images/20230521/d3586fd0d3c04227b74a44b7f84d5940.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 11]: /images/20230521/f30618ebfb4544338ed36f7db688dba8.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 12]: /images/20230521/b7f19f75158a40578115e4892713e5f2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 13]: /images/20230521/e64cce0485d34ce9a249b68931a58c7b.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 14]: /images/20230521/98325e9e9d58449c94d2e2334f3ee976.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 15]: /images/20230521/445ec7bd76a8460389f1311084e402f8.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 16]: /images/20230521/33dfb1fad863443b82ee62d85b06938d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 17]: /images/20230521/8c9f34b2139a416fa4714738d153b607.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 18]: /images/20230521/3276ba7ad0d044faa9bf2fa22afa1314.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NoaWxsX0x5bg_size_16_color_FFFFFF_t_70 19]: /images/20230521/6c4365216c614043acb8d2269a5044d5.png
[20200514194844570.png]: /images/20230521/3d571834084c4f5893de94d6f05a4705.png