SentinelSlot扩展实践流控熔断预警实现

  • Z时代
  • 2024-01-10
  • 分类：综合

编程

这是一个再正常不过的生产问题，可能大部分同学都经历过，经历过的大多数是解决问题之后就不了了之，导致事故还有再次发生的可能，最终对用户造成了不好的体验。所以我觉得所有的生产问题都需要进行复盘，当然复盘的目的不是为了追责，而是防止下次再发生同样的错误。那我们就简单分析一下这个问题，首先肯定是业务层面的疏漏导致task发出不合理的大量请求，其二我们的流控只是简单粗暴的流控，没有更好的预警措施，导致影响到用户之后我们才知晓（即流控或熔断已经触发）。

那我们的解决方案呢？首先肯定是业务层面的预防，但这不是本文要说的重点，这里不展开讨论了。其次就是预警，就是我们能否在快要触发流控之前知晓，然后报警到相关负责人提前介入处理，防止触发流控熔断。当然也不能完全避免，但是总比流控或熔断触发之后在报警要好得多。

由于之前流控用的阿里的Sentinel，所以本文介绍的具体实现是用Sentinel的自定义slot功能，这个自定义slot卡槽在Sentinel官方文档里面就一句话带过，然后加上一个demo代码，我在使用的过程中也遇到过不少坑，所以分享一下结果给大家。

如果大家对Sentinel不是很了解，可以先去github先了解简单试用一下在阅读本文。github地址：https://github.com/alibaba/Sentinel

如果想熟悉自定义slot功能建议了解一下Sentinel的工作原理：https://github.com/alibaba/Sentinel/wiki/Sentinel%E5%B7%A5%E4%BD%9C%E4%B8%BB%E6%B5%81%E7%A8%8B

还有源码中的demo对于自定义slot的写法：https://github.com/alibaba/Sentinel/tree/master/sentinel-demo/sentinel-demo-slot-chain-spi

具体实现

下面介绍下Sentinel预警功能的相关实现，使用的前提是你的系统已经在用Sentinel的流控或熔断等功能。

  1. 自定义CustomSlotChainBuilder实现SlotChainBuilder接口，这里主要是把我们自定义的Slot加到SlotChain这个链中

import com.alibaba.csp.sentinel.slotchain.ProcessorSlotChain;
import com.alibaba.csp.sentinel.slotchain.SlotChainBuilder;
import com.alibaba.csp.sentinel.slots.DefaultSlotChainBuilder;
import com.qiaofang.tortoise.gateway.component.ApplicationContextUtil;
import com.qiaofang.tortoise.gateway.config.SentinelProperties;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
/**
 * 自定义slot
 *
 * @author chenhao
 */
public class CustomSlotChainBuilder implements SlotChainBuilder {
@Override
public ProcessorSlotChain build() {
        ProcessorSlotChain chain = new DefaultSlotChainBuilder().build();
SentinelProperties sentinelProperties = (SentinelProperties) ApplicationContextUtil.getContext().getBean("sentinelProperties");
chain.addLast(new FlowEarlyWarningSlot(sentinelProperties));
chain.addLast(new DegradeEarlyWarningSlot(sentinelProperties));
        return chain;
}
}

2.自定义FlowEarlyWarningSlot、DegradeEarlyWarningSlot 流控熔断2个预警slot

import com.alibaba.csp.sentinel.context.Context;
import com.alibaba.csp.sentinel.node.DefaultNode;
import com.alibaba.csp.sentinel.slotchain.AbstractLinkedProcessorSlot;
import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleChecker;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleUtil;
import com.alibaba.csp.sentinel.util.AssertUtil;
import com.google.common.collect.Lists;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.util.CollectionUtils;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
/**
 * 流控预警slot
 *
 * @author chenhao
 */
public class FlowEarlyWarningSlot2 extends AbstractLinkedProcessorSlot<DefaultNode> {
/**
     * log
     */
private Logger logger = LoggerFactory.getLogger(this.getClass());
    private final FlowRuleChecker checker;
    public FlowEarlyWarningSlot2() {
this(new FlowRuleChecker());
}
/**
     * Package-private for test.
     *
     * @param checker flow rule checker
     * @since 1.6.1
     */
FlowEarlyWarningSlot2(FlowRuleChecker checker) {
        AssertUtil.notNull(checker, "flow checker should not be null");
        this.checker = checker;
}
private List<FlowRule> getRuleProvider(String resource) {
// Flow rule map should not be null.
List<FlowRule> rules = FlowRuleManager.getRules();
List<FlowRule> earlyWarningRuleList = Lists.newArrayList();
        for (FlowRule rule : rules) {
            FlowRule earlyWarningRule = new FlowRule();
BeanUtils.copyProperties(rule, earlyWarningRule);
/**
             * 这里是相当于把规则阈值改成原来的80%，达到提前预警的效果，
             * 这里建议把0.8做成配置
             */
earlyWarningRule.setCount(rule.getCount() * 0.8);
earlyWarningRuleList.add(earlyWarningRule);
}
        Map<String, List<FlowRule>> flowRules = FlowRuleUtil.buildFlowRuleMap(earlyWarningRuleList);
        return flowRules.get(resource);
}
/**
     * get origin rule
     *
     * @param resource
* @return
*/
private FlowRule getOriginRule(String resource) {
        List<FlowRule> originRule = FlowRuleManager.getRules().stream().filter(flowRule -> flowRule.getResource().equals(resource)).collect(Collectors.toList());
        if (CollectionUtils.isEmpty(originRule)) {
return null;
}
return originRule.get(0);
}
@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count, boolean prioritized, Object... args)
throws Throwable {
        String resource = context.getCurEntry().getResourceWrapper().getName();
List<FlowRule> rules = getRuleProvider(resource);
        if (rules != null) {
for (FlowRule rule : rules) {
//这里取到的规则都是配置阈值的80%,这里如果检查到阈值了，说明就是到了真实阈值的80%，既可以发报警给对应负责人了
if (!checker.canPassCheck(rule, context, node, count, prioritized)) {
                    FlowRule originRule = getOriginRule(resource);
String originRuleCount = originRule == null ? "未知" : String.valueOf(originRule.getCount());
logger.info("FlowEarlyWarning:服务{}目前的流量指标已经超过{}，接近配置的流控阈值:{},", resource, rule.getCount(), originRuleCount);
//TODO 报警功能自行实现
break;
}
            }
        }
        fireEntry(context, resourceWrapper, node, count, prioritized, args);
}
@Override
public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
        fireExit(context, resourceWrapper, count, args);
}
}

import com.alibaba.csp.sentinel.context.Context;
import com.alibaba.csp.sentinel.node.DefaultNode;
import com.alibaba.csp.sentinel.slotchain.AbstractLinkedProcessorSlot;
import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
import com.alibaba.csp.sentinel.util.AssertUtil;
import com.google.common.collect.Lists;
import com.qiaofang.tortoise.gateway.config.SentinelProperties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.util.CollectionUtils;
import java.util.List;
import java.util.stream.Collectors;
/**
 * 熔断预警slot
 *
 * @author chenhao
 */
public class DegradeEarlyWarningSlot2 extends AbstractLinkedProcessorSlot<DefaultNode> {
/**
     * log
     */
private Logger logger = LoggerFactory.getLogger(this.getClass());
/**
     * 与流控基本一致 就是取原规则的方式不一样
     * @param resource
* @return
*/
private List<DegradeRule> getRuleProvider(String resource) {
// Flow rule map should not be null.
List<DegradeRule> rules = DegradeRuleManager.getRules();
List<DegradeRule> earlyWarningRuleList = Lists.newArrayList();
        for (DegradeRule rule : rules) {
            DegradeRule earlyWarningRule = new DegradeRule();
BeanUtils.copyProperties(rule, earlyWarningRule);
earlyWarningRule.setCount(rule.getCount() * 0.8);
earlyWarningRuleList.add(earlyWarningRule);
}
return earlyWarningRuleList.stream().filter(rule -> resource.equals(rule.getResource())).collect(Collectors.toList());
}
/**
     * get origin rule
     *
     * @param resource
* @return
*/
private DegradeRule getOriginRule(String resource) {
        List<DegradeRule> originRule = DegradeRuleManager.getRules().stream().filter(rule -> rule.getResource().equals(resource)).collect(Collectors.toList());
        if (CollectionUtils.isEmpty(originRule)) {
return null;
}
return originRule.get(0);
}
@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count, boolean prioritized, Object... args)
throws Throwable {
        String resource = context.getCurEntry().getResourceWrapper().getName();
List<DegradeRule> rules = getRuleProvider(resource);
        if (rules != null) {
for (DegradeRule rule : rules) {
if (!rule.passCheck(context, node, count)) {
                    DegradeRule originRule = getOriginRule(resource);
String originRuleCount = originRule == null ? "未知" : String.valueOf(originRule.getCount());
logger.info("DegradeEarlyWarning:服务{}目前的熔断指标已经超过{}，接近配置的熔断阈值:{},", resource, rule.getCount(), originRuleCount);
                    break;
}
            }
        }
        fireEntry(context, resourceWrapper, node, count, prioritized, args);
}
@Override
public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
        fireExit(context, resourceWrapper, count, args);
}

3.在resources文件夹下面新增META-INF.services文件夹，新增文件com.alibaba.csp.sentinel.slotchain.SlotChainBuilder（文件名无所谓） 内容如下

# 这里写你CustomSlotChainBuilder的完整包路径
com.xxx.sentinel.CustomSlotChainBuilder

到这里基本上就可以了，用的过程中还是遇到挺多坑的，简单列举几个吧

  • 直接改FlowRule的count属性是不行的，因为底层验证规则的时候用的是FlowRule的controller属性，这个属性又是私有的，所以直接先拿到原始的配置后通过FlowRuleUtil重新生成

  • 调试过程中，DefaultNode里面很多方法的值是都是1s内有效，从方法A debug到方法B 可能值就没了，当时一脸懵逼

写在最后

    本人很少写这种技术博客，所以有什么问题，或者不严谨的地方，大家可以提出来，求轻点喷我哈哈哈

以上是 SentinelSlot扩展实践流控熔断预警实现 的全部内容， 来源链接： utcz.com/z/514115.html

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