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Sentinel flow guard

2022-07-05 16:36:00 【Boundless II】

1. background

1.1 brief introduction

Sentinel Take flow as the starting point , Slave flow control 、 Fusing the drop 、 Multiple dimensions such as system load protection protect the stability of services .

Sentinel Has the following characteristics

  • Rich application scenarios ：Sentinel To undertake Alibaba near 10 The core scene of promoting traffic in the double 11 of , For example, seckill （ That is to say, the burst flow is controlled within the range of system capacity ）、 Cut the peak and fill the valley 、 Cluster flow control 、 Real time fuse downstream unavailable applications, etc .
  • Complete real-time monitoring ：Sentinel At the same time, it provides real-time monitoring function . You can see the second level data of a single machine accessing the application in the console , even to the extent that 500 Summary operation of clusters below Taiwan .
  • Broad open source ecosystem ：Sentinel Provides out of the box and other open source frameworks / The integration module of the library , For example, Spring Cloud、Apache Dubbo、gRPC、Quarkus Integration of . You only need to introduce corresponding dependency and make simple configuration to access quickly Sentinel. meanwhile Sentinel Provide Java/Go/C++ And so on .
  • Perfect SPI Extension mechanism ：Sentinel Easy to use 、 Perfect SPI Extension interface . You can quickly customize the logic by implementing the extension interface . For example, custom rule management 、 Adapt to dynamic data sources, etc .

Sentinel The main characteristics of

  • Core library （Java client ） Don't rely on any framework / library , Can run on all Java Runtime environment , At the same time Dubbo / Spring Cloud And other frameworks also have better support .
  • Console （Dashboard） be based on Spring Boot Development , It can run directly after packing , No additional Tomcat Etc. Application containers .

1.2 Learning reference

1.3 Chapter introduction

This article mainly introduces the following knowledge points ：
  • be based on Spring boot docking Sentinel;
  • Nacos To configure Sentinel Rule information ;
  • Test flow control rules , System protection rules , Fusing rules ;
  • Sentinel Console data display problem ;
  • Nacos Rule storage and Sentinel Modify the data synchronization problem ;
  • Sentinel Analysis of responsibility chain model

2. The project build

2.1 pom To configure 

<!--        nacos To configure -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
            <version>2.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2.2.6.RELEASE</version>
        </dependency>
        <!--        sentinel To configure -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>2.2.6.RELEASE</version>
        </dependency>
        <!--        sentinel  Rule based nacos Storage -->
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
            <version>1.8.3</version>
        </dependency>

2.2 Project parameter configuration 

server:
  servlet:
    context-path: /sentinel-nacos-demo
spring:
  application:
    name: sentinel-nacos-demo
  profiles:
    active: local
  cloud:
    nacos:
      config:
        server-addr: xxx.xxx.xx.x:8848
        #server-addr: xxx.xxx.xx.x:8848
group: ${spring.application.name}
        file-extension: yaml
        #  The configuration center uses a separate namespace
namespace: "study"
      discovery:
        server-addr: xxx.xxx.xx.x:8848
        namespace: "study"
        group: "sentinel-nocas-demo"
    sentinel:
      transport:
        dashboard: xxx.xxx.xx.x:8842  # After starting this project, you need to request once to sentinel Console registration 
port: 8719  # When a server deploys multiple applications, it needs to be configured differently port, A single application can be ignored 
client-ip: 10.32.4.230   # Specify native ip Address , Avoid multiple virtual addresses , Leading to data acquisition failure 
datasource:
        ##  Configure process control 
        ## rule-type  Configure the rules that represent the type of rules in the data source (flow Flow control ,degrade Fusing the drop ,authority to grant authorization ,system System protection , param-flow Hot spot parameter current limiting , gw-flow, gw-api-group)
flow:
          nacos:
            server-addr: xxx.xxx.xx.x:8848
            namespace: "study"
            data-id: ${spring.application.name}-sentinel-flow-rules
            group-id: sentinel-group
            data-type: json
            rule-type: flow
              ##  Configure degradation rules 
degrade:
          nacos:
            server-addr: xxx.xxx.xx.x:8848
            namespace: "study"
            dataId: ${spring.application.name}-sentinel-degrade-rules
            groupId: sentinel-group
            data-type: json
            rule-type: degrade
        system:
          nacos:
            server-addr: xxx.xxx.xx.x:8848
            namespace: "study"
            dataId: ${spring.application.name}-sentinel-system-rules
            groupId: sentinel-group
            data-type: json
            rule-type: system

2.3 Rule configuration

stay Nacos The following configurations are set in the configuration center ：

Sentinel Flow control rule configuration 

[
    {
        "resource": "/sentinel/rule/flow",
        "limitApp": "default",
        "grade": 1,
        "count": 1,
        "strategy": 0,
        "controlBehavior": 0,
        "clusterMode": false
    }
]

Sentinel Fuse rule configuration 

[
    {
        "resource": "/sentinel/rule/degrade",
        "count": 1,
        "grade": 0,
        "timeWindow": 10,
        "minRequestAmount": 1,
        "statIntervalMs": 1000,
        "slowRatioThreshold": 0.1
    }
]

Sentinel System protection rule configuration 

[
    {
        "avgRt":1,
        "highestCpuUsage":-1,
        "highestSystemLoad":-1,
        "maxThread":-1,
        "qps":1000
    }
]

2.4 Uniform interception rules 

@Component
public static class MyBlockExceptionHandler implements BlockExceptionHandler {
  @Override
  public void handle(HttpServletRequest httpServletRequest, HttpServletResponse response, BlockException e) throws Exception {
    //Sentinel Details of the rule 
    BaseResponse r = BaseResponse.error("sentinel- Control interception ");
    if (e instanceof FlowException) {
      r = BaseResponse.error(" The interface is current limited ",e.toString());
    } else if (e instanceof DegradeException) {
      r = BaseResponse.error( " The service has been downgraded ",e.toString());
    } else if (e instanceof ParamFlowException) {
      r = BaseResponse.error(" Hot spot parameters are limited ",e.toString());
    } else if (e instanceof SystemBlockException) {
      r = BaseResponse.error( " Triggered the system protection rules ",e.toString());
    } else if (e instanceof AuthorityException) {
      r = BaseResponse.error( " Authorization rules don't pass ",e.toString());
    }
    // return json data 
    response.setStatus(500);
    response.setCharacterEncoding("utf-8");
    response.setContentType(MediaType.APPLICATION_JSON_VALUE);
    new ObjectMapper().writeValue(response.getWriter(), r);
  }
}

3. Example of project operation

3.1 Rule interception test

Sentinel Flow control rule test

Sentinel Fusing rule test

Sentinel System protection rule test

3.2 Sentinel Console interface display

Real-time monitoring

Cluster link

Flow control rules

4. Console data display problem

4.1 Cluster link data is empty

Cause ： There are multiple virtual servers deploying microservices ip Address ,Sentinel The console recognizes one of ip Address , But the address is not connected to the console network .
terms of settlement （ Both of the following methods are ok ）：
1. Set a fixed deployment server ip Address ;
2. Configure a fixed client ip Address , Such as ： 
sentinel:
  transport:
    dashboard: xxx.168.16.13:8842  # After starting this project, you need to request once to sentinel Console registration 
port: 8719  # When a server deploys multiple applications, it needs to be configured differently port, A single application can be ignored 
client-ip: xx.xx.4.230   # Specify native ip Address , Avoid multiple virtual addresses , Leading to data acquisition failure

4.2 The real-time monitoring data is empty

Cause ： The server time to deploy the maintenance service is the same as Sentinel The time of the server where the console is located is inconsistent .
terms of settlement ： Adjust the time of servers on both sides , At a gap of 20 Within seconds , Data can be displayed .

5.Sentinel Console and Nacos Configuration center data consistency problem

Sentinel The console can set various rules through the cluster link , But rule information cannot be stored on the ground . once Sentienl After the service is restarted , The rules will be lost .
The solution can store rule information in Nacos in , In this way, rule information can be stored . The current version is in Nacos After setting the rule information in , Can be in Sentinel View... In the console , But in Sentinel After the console modifies the rule , Can't sync to Nacos in .
In this case , Solution reference is as follows ：
  • The project team uniformly stipulates , Rule information can only be based on Nacos To configure , stay Nacos Make modifications and adjustments , Don't be in Sentinel Console operation rule information .
Personal advice ： At present, it can be based on Nacos Configuration unified management , Subsequent versions should support bidirectional synchronization , When not necessary , There is no need to build wheels .

6.Sentinel Some core source code analysis

This article analyzes the source code version ：sentinel-core-1.8.1
Sentinel take ProcessorSlot As SPI Interface expansion , bring Slot Chain With the ability to expand . Developers can add customized slot And choreograph slot Execution sequence between , So that we can give Sentinel Add custom features .

6.1 Default slot Execution order

slot Implementation class diagram
NodeSelectorSlot Implementation class call relationship ： 
1. Define the loading order of implementation classes 
@Spi(isSingleton = false, order = Constants.ORDER_NODE_SELECTOR_SLOT)

2. Definition NodeSelectorSlot The implementation class inherits from the abstract class 
 public class NodeSelectorSlot extends AbstractLinkedProcessorSlot<Object> 

3. Define abstract classes to implement interfaces 
public abstract class AbstractLinkedProcessorSlot<T> implements ProcessorSlot<T>

4. Define the top-level interface of the link 
public interface ProcessorSlot<T>

6.2 Build default responsibility chain

Loading implements abstract classes AbstractLinkedProcessorSlot The link to , If only ProcessorSlot Interface , It cannot be added to the responsibility link . Reference source code ： 
public class DefaultSlotChainBuilder implements SlotChainBuilder {

    @Override
    public ProcessorSlotChain build() {
        ProcessorSlotChain chain = new DefaultProcessorSlotChain();

        List<ProcessorSlot> sortedSlotList = SpiLoader.of(ProcessorSlot.class).loadInstanceListSorted();
        for (ProcessorSlot slot : sortedSlotList) {
            if (!(slot instanceof AbstractLinkedProcessorSlot)) {
                RecordLog.warn("The ProcessorSlot(" + slot.getClass().getCanonicalName() + ") is not an instance of AbstractLinkedProcessorSlot, can't be added into ProcessorSlotChain");
                continue;
            }

            chain.addLast((AbstractLinkedProcessorSlot<?>) slot);
        }

        return chain;
    }
}
Historical call chain assembly logic ： When debugging code , It is found that the new version has abandoned this call assembly logic .( The chain of responsibility model , combination order Sequential mode , Easy to adjust and control ) 
public abstract class ProcessorSlotChain extends AbstractLinkedProcessorSlot<Object> {

    /**
     * Add a processor to the head of this slot chain.
     *
     * @param protocolProcessor processor to be added.
     */
public abstract void addFirst(AbstractLinkedProcessorSlot<?> protocolProcessor);

    /**
     * Add a processor to the tail of this slot chain.
     *
     * @param protocolProcessor processor to be added.
     */
public abstract void addLast(AbstractLinkedProcessorSlot<?> protocolProcessor);
}

6.3 Process summary

  • Using the chain of responsibility model to complete Sentinel Information statistics of 、 Fuse 、 Current limiting and other operations ;
  • In the chain of responsibility NodeSelectSlot Responsible for selecting the current resource Node, At the same time build node Call tree ;
  • In the chain of responsibility ClusterBuilderSlot Currently responsible for building Node Corresponding ClusterNode, Used to aggregate the same resource corresponding to different Context Of Node;
  • In the chain of responsibility StatisticSlot It is used to count the call status of the current resource , to update Node It's not the right thing to use ClusterNode All kinds of Statistics ;
  • In the chain of responsibility FlowSlot Based on the current Node Corresponding ClusterNode（ Default ） The statistical flow limit of information ;
  • Resource call statistics （ for example PassQps） Use the sliding time window for statistics ;
  • After all the work has been done , Execute the exit process , Add some statistics , clear Context.

6.4 Write a custom intercept Slot

/**
 *  Write a custom current limiting link 
 *
 * @author wangling
 * @date 2022/07/05
 */
@Spi(order = -3000)
public class TestMySlot extends AbstractLinkedProcessorSlot<DefaultNode> {

    @Override
    public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode obj, int count, boolean prioritized, Object... args)
        throws Throwable {
        try {
            fireEntry(context, resourceWrapper, obj, count, prioritized, args);
            throw new BusinessException("TestMySlot- test ");
        } catch (Exception e) {
            throw e;
        } catch (Throwable e) {
            RecordLog.warn("Unexpected entry exception", e);
        }

    }

    @Override
    public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
        try {
            fireExit(context, resourceWrapper, count, args);
        } catch (Throwable e) {
            RecordLog.warn("Unexpected entry exit exception", e);
        }
    }
}
To configure SPI Automatic scanning
 
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本文为[Boundless II]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/186/202207051600105822.html

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