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Alibaba Sentinel 规则持久化-拉模式-手把手教程【基于文件】

目录

本文实现基于拉模式的Alibaba Sentinel规则持久化。

一、拉模式架构

TIPS

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

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

3.2 写代码

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/**
* 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:

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# 改成上面FileDataSourceInit的包名类名全路径即可。
com.itmuch.contentcenter.FileDataSourceInit

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?

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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,可以看我提的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

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