Alibaba Sentinel规则持久化-拉模式-手把手教程【基于文件】

文章目录

• ​​一、拉模式架构​​
• ​​二、原理简述​​
• ​​三、编写​​

• ​​3.1 加依赖​​
• ​​3.2 写代码​​
• ​​3.3 配置​​

• ​​四、优缺点分析​​
• ​​五、你可能会有的疑问​​
• ​​六、参考文档​​
• ​​七、案例测试​​

• ​​7.1. 添加流控规则​​
• ​​7.2. 服务停止​​
• ​​7.3. 重新启动服务​​
• ​​7.4. 调用接口​​
• ​​7.5. 查看流控规则​​

本文实现基于拉模式的Alibaba Sentinel规则持久化。

一、拉模式架构

图片来自官方。
引用自 https://github.com/alibaba/Sentinel/wiki/在生产环境中使用-Sentinel

二、原理简述

FileRefreshableDataSource 定时从指定文件中读取规则JSON文件【图中的本地文件】，如果发现文件发生变化，就更新规则缓存。
FileWritableDataSource 接收控制台规则推送，并根据配置，修改规则JSON文件【图中的本地文件】。

三、编写

修改Spring Cloud Alibaba微服务。

3.1 加依赖

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

3.2 写代码

package com.itmuch.contentcenter.sentinel;

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;

/**
 * 拉模式规则持久化
 *
 * @author itmuch.com
 */
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 paramFlowRulePath = ruleDir + "/param-flow-rule.json";

        this.mkdirIfNotExits(ruleDir);
        this.createFileIfNotExits(flowRulePath);
        this.createFileIfNotExits(degradeRulePath);
        this.createFileIfNotExits(systemRulePath);
        this.createFileIfNotExits(authorityRulePath);
        this.createFileIfNotExits(paramFlowRulePath);

        // 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<>(
            authorityRulePath,
            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>> paramFlowRuleRDS = new FileRefreshableDataSource<>(
            paramFlowRulePath,
            paramFlowRuleListParser
        );
        ParamFlowRuleManager.register2Property(paramFlowRuleRDS.getProperty());
        WritableDataSource<List<ParamFlowRule>> paramFlowRuleWDS = new FileWritableDataSource<>(
            paramFlowRulePath,
            this::encodeJson
        );
        ModifyParamFlowRulesCommandHandler.setWritableDataSource(paramFlowRuleWDS);
    }

    private Converter<String, List<FlowRule>> flowRuleListParser = source -> JSON.parseObject(
        source,
        new TypeReference<List<FlowRule>>() {
        }
    );
    private Converter<String, List<DegradeRule>> degradeRuleListParser = source -> JSON.parseObject(
        source,
        new TypeReference<List<DegradeRule>>() {
        }
    );
    private Converter<String, List<SystemRule>> systemRuleListParser = source -> JSON.parseObject(
        source,
        new TypeReference<List<SystemRule>>() {
        }
    );

    private Converter<String, List<AuthorityRule>> authorityRuleListParser = source -> JSON.parseObject(
        source,
        new TypeReference<List<AuthorityRule>>() {
        }
    );

    private Converter<String, List<ParamFlowRule>> paramFlowRuleListParser = source -> JSON.parseObject(
        source,
        new TypeReference<List<ParamFlowRule>>() {
        }
    );

    private void mkdirIfNotExits(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            file.mkdirs();
        }
    }

    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);
    }
}

3.3 配置

在项目的 ​​resources/META-INF/services​​​ 目录下创建文件，名为 ​​com.alibaba.csp.sentinel.init.InitFunc​​ ，内容为：

# 改成上面FileDataSourceInit的包名类名全路径即可。

四、优缺点分析

优点:
简单易懂
没有多余依赖（比如配置中心、缓存等）
缺点:
由于规则是用 FileRefreshableDataSource 定时更新的，所以规则更新会有延迟。如果FileRefreshableDataSource定时时间过大，可能长时间延迟；如果FileRefreshableDataSource过小，又会影响性能；
规则存储在本地文件，如果有一天需要迁移微服务，那么需要把规则文件一起迁移，否则规则会丢失。

五、你可能会有的疑问

Spring Cloud Alibaba不是提供了如下配置了吗？为什么要全部自己写呢？

spring.cloud.sentinel.datasource.ds1.file.file=classpath: degraderule.json
spring.cloud.sentinel.datasource.ds1.file.rule-type=flow

#spring.cloud.sentinel.datasource.ds1.file.file=classpath: flowrule.json
#spring.cloud.sentinel.datasource.ds1.file.data-type=custom
#spring.cloud.sentinel.datasource.ds1.file.converter-class=com.alibaba.cloud.examples.JsonFlowRuleListConverter
#spring.cloud.sentinel.datasource.ds1.file.rule-type=flow

关于这个问题，可以参考提的Issue​​https://github.com/alibaba/spring-cloud-alibaba/issues/756)​​：

六、参考文档

https://github.com/alibaba/Sentinel/wiki/在生产环境中使用-Sentinel#pull模式

七、案例测试

7.1. 添加流控规则

簇点链路-流控

7.2. 服务停止

停止内容中心和Sentinel控制台

7.3. 重新启动服务

重新启动Sentinel控制台和内容中心

7.4. 调用接口

由于Sentinel控制台采用的是懒加载策略，因此，需要请求一次接口，再刷新

http://localhost:8010/shares/1

7.5. 查看流控规则

刷新Sentinel控制台，查看流控规则