对于规则管理及推送，规则的推送有三种模式：
原始模式：API 将规则推送至客户端并直接更新到内存中，扩展写数据源（WritableDataSource）
这种模式简单，无任何依赖。但是不保证一致性；规则保存在内存中，重启即消失。所以不适用与生产环境，我们需要实现规则的持久话。Sentinel给我们提供了两种持久化方法，就是规则的另外两种推送模式。
Pull 模式：扩展写数据源（WritableDataSource）， 客户端主动向某个规则管理中心定期轮询拉取规则，这个规则中心可以是 RDBMS、文件 等。优点是简单，无任何依赖；规则持久化。缺点是不保证一致性；实时性不保证，拉取过于频繁也可能会有性能问题。
Push 模式：扩展读数据源（ReadableDataSource），规则中心统一推送，客户端通过注册监听器的方式时刻监听变化，比如使用 Nacos、Zookeeper 等配置中心。这种方式有更好的实时性和一致性保证。生产环境下一般采用 push 模式的数据源。优点是规则持久化；一致性；快速。缺点是引入了第三方依赖。
Pull 模式【拉模式】
Pull模式架构图
实现方式
添加依赖
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-extension</artifactId>
</dependency>
持久化代码
/**
* PULL规则持久化
*/
public class FileDataSourceInit implements InitFunc {
@Override
public void init() throws Exception {
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);
// 注册一个可读数据源，用来定时读取本地的json文件，更新到规则缓存中
// 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);
}
}
添加配置
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：
上面FileDataSourceInit的包名类名全路径
Push模式
Push模式架构图
微服务改造
添加依赖
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-nacos</artifactId>
</dependency>
添加配置
spring:
cloud:
sentinel:
datasource:
# 名称随意
flow:
nacos:
server-addr: localhost:8848
dataId: ${spring.application.name}-flow-rules
groupId: SENTINEL_GROUP
# 规则类型，取值见：
# org.springframework.cloud.alibaba.sentinel.datasource.RuleType
rule-type: flow
degrade:
nacos:
server-addr: localhost:8848
dataId: ${spring.application.name}-degrade-rules
groupId: SENTINEL_GROUP
rule-type: degrade
system:
nacos:
server-addr: localhost:8848
dataId: ${spring.application.name}-system-rules
groupId: SENTINEL_GROUP
rule-type: system
authority:
nacos:
server-addr: localhost:8848
dataId: ${spring.application.name}-authority-rules
groupId: SENTINEL_GROUP
rule-type: authority
param-flow:
nacos:
server-addr: localhost:8848
dataId: ${spring.application.name}-param-flow-rules
groupId: SENTINEL_GROUP
rule-type: param-flow
控制台改造
控制台改造主要是为规则实现，需要修改源码，从https://github.com/alibaba/Sentinel 地址下载源码，进入sentinel-dashboard目录进行修改
- 修改pom.xml文件【sentinel-dashboard模块下】
将：
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-nacos</artifactId>
<scope>test</scope>
</dependency>
改为：
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-nacos</artifactId>
</dependency>
找到sentinel-dashboard/src/test/java/com/alibaba/csp/sentinel/dashboard/rule/nacos目录，将整个目录拷贝到 sentinel-dashboard/src/main/java/com/alibaba/csp/sentinel/dashboard/rule/nacos
修改 com.alibaba.csp.sentinel.dashboard.controller.v2.FlowControllerV2
将：
@Autowired
@Qualifier("flowRuleDefaultProvider")
private DynamicRuleProvider<List<FlowRuleEntity>> ruleProvider;
@Autowired
@Qualifier("flowRuleDefaultPublisher")
private DynamicRulePublisher<List<FlowRuleEntity>> rulePublisher;
改为：
@Autowired
@Qualifier("flowRuleNacosProvider")
private DynamicRuleProvider<List<FlowRuleEntity>> ruleProvider;
@Autowired
@Qualifier("flowRuleNacosPublisher")
private DynamicRulePublisher<List<FlowRuleEntity>> rulePublisher;
- 修改 sentinel-dashboard/src/main/webapp/resources/app/scripts/directives/sidebar/sidebar.html
将：
<!--<li ui-sref-active="active" ng-if="entry.appType==0">-->
<!--<a ui-sref="dashboard.flow({app: entry.app})">-->
<!--<i class="glyphicon glyphicon-filter"></i> 流控规则 V1</a>-->
<!--</li>-->
改为：
<li ui-sref-active="active" ng-if="entry.appType==0">
<a ui-sref="dashboard.flow({app: entry.app})">
<i class="glyphicon glyphicon-filter"></i> 流控规则 V1</a>
</li>
自此，流控规则更改为Push持久化，其他规则等照修改
编辑/启动
生产环境使用
推荐使用Push模式
也可以使用阿里云提供的在线托管Sentinel控制台：AHAS