3种规则配置方式

硬编码

sentinel的每种RuleManager提供了API来修改规则（loadRules）

例如：

FlowRuleManager.loadRules(List<FlowRule> rules); // 修改流控规则
DegradeRuleManager.loadRules(List<DegradeRule> rules); // 修改降级规则

DataSource-pull（拉模式）

• 自定义拉取规则：可以继承 AutoRefreshDataSource 抽象类，然后实现 readSource() 方法，在该方法里从指定数据源读取字符串格式的配置数据。

• 官方提供了使用文件配置规则的方式

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-extension</artifactId>
    <version>x.y.z</version>
</dependency>

接入方式：

private void init() throws Exception {
    // 保存了限流规则的文件的地址
    String flowRuleName = yourFlowRuleFileName();
    Converter<String, List<FlowRule>> parser = source -> JSON.parseObject(source,new TypeReference<List<FlowRule>>() {});
    // 创建文件规则数据源
    FileRefreshableDataSource<List<FlowRule>> flowRuleDataSource = new FileRefreshableDataSource<>(flowRuleName, parser);
    // 将Property注册到 RuleManager 中去
    FlowRuleManager.register2Property(flowRuleDataSource.getProperty());
}

FileRefreshableDataSource 会周期性的读取文件以获取规则，当文件有更新时会及时发现，并将规则更新到内存中。

DataSource-push（推模式）

实现推模式的数据源最简单的方式是继承 AbstractDataSource 抽象类，在其构造方法中添加监听器，并实现 readSource() 从指定数据源读取字符串格式的配置数据。

• 官方提供4种规则中心
• redis

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-redis</artifactId>
    <version>x.y.z</version>
</dependency>

接入方式：

private void init() throws Exception {
    String redisHost = yourRedisHost();
    String redisPort = yourRedisPort();
    String ruleKey = yourRuleKey();
    String channel = yourChannel();
    Converter<String, List<FlowRule>> parser = source -> JSON.parseObject(source,new TypeReference<List<FlowRule>>() {});
    RedisConnectionConfig config = RedisConnectionConfig.builder()
        .withHost(redisHost)
        .withPort(redisPort)
        .build();
    ReadableDataSource<String, List<FlowRule>> redisDataSource = new RedisDataSource<>(config, ruleKey, channel, parser);
    FlowRuleManager.register2Property(redisDataSource.getProperty());
}

• nacos

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-nacos</artifactId>
    <version>x.y.z</version>
</dependency>

接入方式：

private void init() throws Exception {
    String remoteAddress = yourRemoteAddress();
    String groupId = yourGroupId();
    String dataId = yourDataId();
    Converter<String, List<FlowRule>> parser = source -> JSON.parseObject(source,new TypeReference<List<FlowRule>>() {});
    ReadableDataSource<String, List<FlowRule>> nacosDataSource = new NacosDataSource<>(remoteAddress, groupId, dataId, parser);
    FlowRuleManager.register2Property(nacosDataSource.getProperty());
}

• ZK

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-zookeeper</artifactId>
    <version>x.y.z</version>
</dependency>

接入方式：

private void init() throws Exception {
    String remoteAddress = yourRemoteAddress();
    String path = yourPath();
    Converter<String, List<FlowRule>> parser = source -> JSON.parseObject(source,new TypeReference<List<FlowRule>>() {});
    ReadableDataSource<String, List<FlowRule>> zookeeperDataSource = new ZookeeperDataSource<>(remoteAddress, path, parser);
    FlowRuleManager.register2Property(zookeeperDataSource.getProperty());
}

• Apollo

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-apollo</artifactId>
    <version>x.y.z</version>
</dependency>

接入方式：

private void init() throws Exception {
    String namespaceName = yourNamespaceName();
    String ruleKey = yourRuleKey();
    String defaultRules = yourDefaultRules();
    Converter<String, List<FlowRule>> parser = source -> JSON.parseObject(source,new TypeReference<List<FlowRule>>() {});
    ReadableDataSource<String, List<FlowRule>> apolloDataSource = new ApolloDataSource<>(namespaceName, ruleKey, path, defaultRules);
    FlowRuleManager.register2Property(apolloDataSource.getProperty());
}