Nepxion Discovery学习笔记5 Sentinel流量防卫兵/服务容错综合方案

笔记1:

Sentinel规则持久化:

通过Dashboard来为每个Sentinel客户端设置各种各样的规则，但是这里有一个问题，就是这些规则默认是存放在内存(一旦服务重启规则就随之删除了)中，极不稳定，所以需要将其持久化。

本地文件数据源会定时轮询文件的变更，读取规则。这样我们既可以在应用本地直接修改文件来更 新规则，也可以通过 Sentinel 控制台推送规则。以本地文件数据源为例，推送过程如下图所示：

首先 Sentinel 控制台通过 API 将规则推送至客户端并更新到内存中，接着注册的写数据源会将新的规则保存到本地的文件中。

Sentinel 持久化的方式有2种:

第一种:通过 API 将规则推送至客户端并更新到内存中，接着注册的写数据源会将新的 规则保存到本地的文件中。

1.添加依赖

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

2.自定义Sentinel存储文件数据源加载类:

import com.alibaba.csp.sentinel.command.handler.ModifyParamFlowRulesCommandHandler;
import com.alibaba.csp.sentinel.datasource.*;
import com.alibaba.csp.sentinel.init.InitFunc;
import com.alibaba.csp.sentinel.slots.block.authority.AuthorityRule;
import com.alibaba.csp.sentinel.slots.block.authority.AuthorityRuleManager;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowRule;
import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowRuleManager;
import com.alibaba.csp.sentinel.slots.system.SystemRule;
import com.alibaba.csp.sentinel.slots.system.SystemRuleManager;
import com.alibaba.csp.sentinel.transport.util.WritableDataSourceRegistry;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * FileDataSourceInit for : 自定义Sentinel存储文件数据源加载类
 *
 * @author <a href="mailto:[email protected]">Isaac.Zhang | 若初</a>
 * @since 2019/7/21
 */
public class FileDataSourceInit implements InitFunc {
    @Override
    public void init() throws Exception {
        // TIPS: 如果你对这个路径不喜欢，可修改为你喜欢的路径
        String ruleDir = System.getProperty("user.home") + "/sentinel/rules";
        String flowRulePath = ruleDir + "/flow-rule.json";
        String degradeRulePath = ruleDir + "/degrade-rule.json";
        String systemRulePath = ruleDir + "/system-rule.json";
        String authorityRulePath = ruleDir + "/authority-rule.json";
        String hotParamFlowRulePath = ruleDir + "/param-flow-rule.json";

        this.mkdirIfNotExits(ruleDir);
        this.createFileIfNotExits(flowRulePath);
        this.createFileIfNotExits(degradeRulePath);
        this.createFileIfNotExits(systemRulePath);
        this.createFileIfNotExits(authorityRulePath);
        this.createFileIfNotExits(hotParamFlowRulePath);
        // 流控规则
        ReadableDataSource<String, List<FlowRule>> flowRuleRDS = new FileRefreshableDataSource<>(
                flowRulePath,
                flowRuleListParser
        );
        // 将可读数据源注册至FlowRuleManager
        // 这样当规则文件发生变化时，就会更新规则到内存
        FlowRuleManager.register2Property(flowRuleRDS.getProperty());
        WritableDataSource<List<FlowRule>> flowRuleWDS = new FileWritableDataSource<>(
                flowRulePath,
                this::encodeJson
        );
        // 将可写数据源注册至transport模块的WritableDataSourceRegistry中
        // 这样收到控制台推送的规则时，Sentinel会先更新到内存，然后将规则写入到文件中
        WritableDataSourceRegistry.registerFlowDataSource(flowRuleWDS);

        // 降级规则
        ReadableDataSource<String, List<DegradeRule>> degradeRuleRDS = new FileRefreshableDataSource<>(
                degradeRulePath,
                degradeRuleListParser
        );
        DegradeRuleManager.register2Property(degradeRuleRDS.getProperty());
        WritableDataSource<List<DegradeRule>> degradeRuleWDS = new FileWritableDataSource<>(
                degradeRulePath,
                this::encodeJson
        );
        WritableDataSourceRegistry.registerDegradeDataSource(degradeRuleWDS);

        // 系统规则
        ReadableDataSource<String, List<SystemRule>> systemRuleRDS = new FileRefreshableDataSource<>(
                systemRulePath,
                systemRuleListParser
        );
        SystemRuleManager.register2Property(systemRuleRDS.getProperty());
        WritableDataSource<List<SystemRule>> systemRuleWDS = new FileWritableDataSource<>(
                systemRulePath,
                this::encodeJson
        );
        WritableDataSourceRegistry.registerSystemDataSource(systemRuleWDS);

        // 授权规则
        ReadableDataSource<String, List<AuthorityRule>> authorityRuleRDS = new FileRefreshableDataSource<>(
                flowRulePath,
                authorityRuleListParser
        );
        AuthorityRuleManager.register2Property(authorityRuleRDS.getProperty());
        WritableDataSource<List<AuthorityRule>> authorityRuleWDS = new FileWritableDataSource<>(
                authorityRulePath,
                this::encodeJson
        );
        WritableDataSourceRegistry.registerAuthorityDataSource(authorityRuleWDS);

        // 热点参数规则
        ReadableDataSource<String, List<ParamFlowRule>> hotParamFlowRuleRDS = new FileRefreshableDataSource<>(
                hotParamFlowRulePath,
                hotParamFlowRuleListParser
        );
        ParamFlowRuleManager.register2Property(hotParamFlowRuleRDS.getProperty());
        WritableDataSource<List<ParamFlowRule>> paramFlowRuleWDS = new FileWritableDataSource<>(
                hotParamFlowRulePath,
                this::encodeJson
        );
        ModifyParamFlowRulesCommandHandler.setWritableDataSource(paramFlowRuleWDS);
    }

    /**
     * 流控规则对象转换
     */
    private Converter<String, List<FlowRule>> flowRuleListParser = source -> JSON.parseObject(
            source,
            new TypeReference<List<FlowRule>>() {
            }
    );
    /**
     * 降级规则对象转换
     */
    private Converter<String, List<DegradeRule>> degradeRuleListParser = source -> JSON.parseObject(
            source,
            new TypeReference<List<DegradeRule>>() {
            }
    );
    /**
     * 系统规则对象转换
     */
    private Converter<String, List<SystemRule>> systemRuleListParser = source -> JSON.parseObject(
            source,
            new TypeReference<List<SystemRule>>() {
            }
    );

    /**
     * 授权规则对象转换
     */
    private Converter<String, List<AuthorityRule>> authorityRuleListParser = source -> JSON.parseObject(
            source,
            new TypeReference<List<AuthorityRule>>() {
            }
    );

    /**
     * 热点规则对象转换
     */
    private Converter<String, List<ParamFlowRule>> hotParamFlowRuleListParser = source -> JSON.parseObject(
            source,
            new TypeReference<List<ParamFlowRule>>() {
            }
    );

    /**
     * 创建目录
     *
     * @param filePath
     */
    private void mkdirIfNotExits(String filePath) {
        File file = new File(filePath);
        if (!file.exists()) {
            file.mkdirs();
        }
    }

    /**
     * 创建文件
     *
     * @param filePath
     * @throws IOException
     */
    private void createFileIfNotExits(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            file.createNewFile();
        }
    }

    private <T> String encodeJson(T t) {
        return JSON.toJSONString(t);
    }
}

3.在resource下创建 resources/META-INF/services 目录并创建文件com.alibaba.csp.sentinel.init.InitFunc写入:

com.sxzhongf.sharedcenter.configuration.sentinel.datasource.FileDataSourceInit

这个方法我没试过,因为缺点很大:

1. 不保证一致性（规则是使用FileRefreshableDataSource定时更新，会有延迟）

2. 实时性不保证（规则是使用FileRefreshableDataSource定时更新）

3. 拉取过于频繁也可能会有性能问题

4. 由于文件存储于本地，容易丢失

 

我推荐使用第二种:

1.导入依赖:

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

2.修改配置

server:
  port: 8091
#  tomcat:
#    max-threads: 10 #tomcat的最大并发值修改为10,默认是200
spring:
  application:
    name: service-order
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/shop?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
    username: root
    password: root
  cloud:
    nacos: #nacos的作用就是一个注册中心
      discovery:
        server-addr: localhost:8848
    sentinel:
    # Sentinel是个springboot项目的控制台, 提供服务容错方案,通过流量控制、熔断降级、系统负载保护来维持服务的稳定性
    # cmd命令窗口启动Sentinel控制台命令:(cd 到 jar包所在目录)
    # java -Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8080 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard-1.7.2.jar
    # -Dserver.port 是sentinel服务地址, -Dcsp.sentinel.dashboard.server是控制台服务地址
    # 若启动多个应用，则需要通过 -Dcsp.sentinel.api.port=xxxx 指定客户端监控 API 的端口
      transport:
        port: 9998 # 指定流控服务的地址, 不同微服务的该端口不可一致
        # 跟控制台交流的端口,随意指定一个未被占用的端口即可
        dashboard: localhost:8080 # Sentinel控制台地址
      filter: # 关闭sentinel的CommonFilter实例化,否则无法实现 链路流控 规则
        enabled: false
      # 流控规则持久化到nacos
      datasource:
        dsl:
          nacos:
            server-addr: localhost:8848
            data-id: ${spring.application.name}
            group-id: DEFAULT_GROUP
            data-type: json
            rule-type: flow # 规则类型，取值见：org.springframework.cloud.alibaba.sentinel.datasource.RuleType
jpa:
  properties:
    hibernate:
      hbm2ddl:
        auto: update
      dialect: org.hibernate.dialect.MySQL5InnoDBDialect

3.在nacos注册中心中,点击配置列表,新建一个配置:

输入配置代码,即可创建限流或降级等规则:

[
    {
        "resource": "/order/message5",  
        "limitApp": "default",         
        "grade": 1,                     
        "count": 5,                     
        "strategy": 0,                  
        "controlBehavior": 0,           
        "clusterMode": false            
    }
]

//resource：资源名，即限流规则的作用对象
//limitApp：流控针对的调用来源，若为default则不区分调用来源
//grade：限流阈值类型（1:QPS, 0:线程数）
//count：限流阈值
//strategy：调用关系限流策略(0:直接, 1:关联, 2:链路)
//controlBehavior：流量控制效果（0:直接拒绝, 1:WarmUp, 2:匀速排队）
//clusterMode: 是否集群

4.测试:重启服务后sentinel中的流控规则永久存在,并和nacos新建的配置对应: