基于重写ribbon负载实现灰度发布

项目结构如下

代码如下：

pom：

java 复制代码

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>sca.pro</groupId>
        <artifactId>sca-parent</artifactId>
        <version>1.0.1</version>
    </parent>

    <groupId>sca.gary.publish</groupId>
    <artifactId>gray-spring-boot-starter</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- Compile dependencies -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>com.netflix.ribbon</groupId>
            <artifactId>ribbon-loadbalancer</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>transmittable-thread-local</artifactId>
            <version>2.14.2</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-core</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>${project.build.sourceEncoding}</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

spring.factories

java 复制代码

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
sca.gary.publish.graypublish.config.GrayConfig,\
sca.gary.publish.graypublish.feignInterceptor.FeignRequestInterceptor

GrayConfig：可以在对应服务启动类添加如下，可写多个服务

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@RibbonClients(value = {
        @RibbonClient(value = "nacos中的服务名称",configuration = GrayConfig.class)
})

java 复制代码

package sca.gary.publish.graypublish.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import sca.gary.publish.graypublish.GrayRule;

//@Configuration
之前理解有误，这里千万不能加它，否则服务调用会混乱
public class GrayConfig {
    @Bean
    public GrayRule grayRule(){
        return new GrayRule();
    }
}

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ContantsString：版本号请求头key

java 复制代码

package sca.gary.publish.graypublish.contans;

public class ContantsString {
    public static final String GRAY_KEY="version";

}

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FeignRequestInterceptor：feign拦截器，当远程调用时，将版本号保存到ttl中，供给服务负载使用，并把当前请求头中的版本号放在远程调用的请求头中，防止它仍需要远程调用

java 复制代码

package sca.gary.publish.graypublish.feignInterceptor;

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.context.annotation.Import;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import sca.gary.publish.graypublish.contans.ContantsString;
import sca.gary.publish.graypublish.ttl.ThreadLocalUtils;

import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.Map;

@Component
public class FeignRequestInterceptor  implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        ServletRequestAttributes sra = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = sra.getRequest();
        Map<String, String> headers = getHeaders(request);
        for (Map.Entry<String, String> entry : headers.entrySet()) {
            //② 设置请求头到新的Request中
            template.header(entry.getKey(), entry.getValue());
        }
    }

    /**
     * 获取原请求头
     */
    private Map<String, String> getHeaders(HttpServletRequest request) {
        Map<String, String> map = new LinkedHashMap<>();
        Enumeration<String> enumeration = request.getHeaderNames();
        if (enumeration != null) {
            while (enumeration.hasMoreElements()) {
                String key = enumeration.nextElement();
                String value = request.getHeader(key);
                //将灰度标记的请求头透传给下个服务
                if (ContantsString.GRAY_KEY.equals(key)){
                    //① 保存灰度发布的标记
                    ThreadLocalUtils.set(ContantsString.GRAY_KEY,value);
                    map.put(key, value);
                }
            }
        }
        return map;
    }
}

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ThreadLocalUtils：用于存储网关传递过来的版本号，实现当前服务的负载选择

java 复制代码

package sca.gary.publish.graypublish.ttl;

import com.alibaba.ttl.TransmittableThreadLocal;
import java.util.HashMap;
import java.util.Map;

public class ThreadLocalUtils {

    private static TransmittableThreadLocal<Map<String, Object>> cache = new TransmittableThreadLocal<>();

    /**
     * 设置对象到本地变量
     *
     * @param object
     */
    public static void set(String key, Object object) {
        if (!isCaheIsNull()) {
            cache.get().put(key, object);
        } else {
            Map<String, Object> map = new HashMap<>();
            map.put(key, object);
            cache.set(map);
        }
    }

    /**
     * 从本地变量中获取变量
     *
     * @return
     */
    public static Object get(String key) {
        if (!isCaheIsNull()) {
            return cache.get().get(key);
        } else {
            return null;
        }
    }


    /**
     * 根据KEY移除缓存里的数据
     *
     * @param key
     */
    public static void remove(String key) {
        if (isCaheIsNull()) {
            return;
        } else {
            cache.get().remove(key);
        }
    }

    /**
     * 释放本地线程资源
     */
    public static void clear() {
        cache.remove();
    }

    /**
     * 是否存在本地变量
     *
     * @return
     */
    private static boolean isCaheIsNull() {
        return cache.get() == null;
    }

}

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GrayRule：

最重要的就是这个类，重写了ribbon的负载策略，通过从网关传递过来的版本号，和每个服务中的元数据版本号进行对比，如果相同则调用它们的版本，如果没有找到对应版本的服务，则将获取到的所有服务按照原规则进行负载

java 复制代码

package sca.gary.publish.graypublish;

import com.alibaba.cloud.nacos.ribbon.NacosServer;
import com.google.common.base.Optional;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.Server;
import com.netflix.loadbalancer.ZoneAvoidanceRule;
import org.springframework.util.ObjectUtils;
import sca.gary.publish.graypublish.contans.ContantsString;
import sca.gary.publish.graypublish.ttl.ThreadLocalUtils;

import java.util.ArrayList;
import java.util.List;

public class GrayRule extends ZoneAvoidanceRule {

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {
    }

    @Override
    public Server choose(Object key) {
        try {
            //从ThreadLocal中获取灰度标记
            Object version = ThreadLocalUtils.get(ContantsString.GRAY_KEY);

            //获取所有可用服务
            List<Server> serverList = this.getLoadBalancer().getReachableServers();
            //灰度发布的服务
            List<Server> grayServerList = new ArrayList<>();
            if (ObjectUtils.isEmpty(version)){
                return originChoose(serverList,key);
            }
            for(Server server : serverList) {
                NacosServer nacosServer = (NacosServer) server;
                //从nacos中获取元素剧进行匹配
                if(nacosServer.getMetadata().containsKey(ContantsString.GRAY_KEY)
                        && nacosServer.getMetadata().get(ContantsString.GRAY_KEY).equals(version.toString()) ){
                    grayServerList.add(server);
                }
            }
            if (!ObjectUtils.isEmpty(grayServerList)){
                return originChoose(grayServerList,key);
            }
            return originChoose(serverList,key);
        } finally {
            //清除灰度标记
            ThreadLocalUtils.clear();
        }
    }

    private Server originChoose(List<Server> noMetaServerList, Object key) {
        Optional<Server> serverOptional = getPredicate().chooseRoundRobinAfterFiltering(noMetaServerList, key);
        if (serverOptional.isPresent()) {
            return serverOptional.get();
        } else {
            return null;
        }
    }


}

使用方式：

1.首先保证每个服务都有feign的依赖

2.添加依赖如下

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<dependency>
    <groupId>sca.gary.publish</groupId>
    <artifactId>gray-spring-boot-starter</artifactId>
    <version>1.0.1</version>
    <exclusions>
        <exclusion>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-core</artifactId>
        </exclusion>
    </exclusions>
</dependency>

3.yaml添加配置

spring:

cloud:

nacos:

discovery:

metadata:

version: 2.0

3.在启动类上添加下边的，需要远程调用哪个服务，就加哪几个

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@RibbonClients(value = {
        @RibbonClient(value = "服务名",configuration = GrayConfig.class)
})