Spring cloud如何实现FeignClient指定Zone调用

# 当前实例所在区域，同时由于NIWSServerListFilterClassName配置的是ZoneAffinityServerListFilter并且EnableZoneAffinity和EnableZoneExclusivity都是true，只有处于同一个zone的实例才会被调用
eureka.instance.metadata-map.zone=local
service-provider.ribbon.NFLoadBalancerRuleClassName=com.netflix.loadbalancer.AvailabilityFilteringRule
service-provider.ribbon.NIWSServerListFilterClassName=com.netflix.loadbalancer.ZoneAffinityServerListFilter
service-provider.ribbon.EnableZoneAffinity=true
service-provider.ribbon.EnableZoneExclusivity=true
service-provider.ribbon.NFLoadBalancerRuleClassName=com.netflix.loadbalancer.AvailabilityFilteringRule
# ribbon.ServerListRefreshInterval时间内有多少断路次数就触发断路机制
niws.loadbalancer.service-provider.connectionFailureCountThreshold=3
niws.loadbalancer.service-provider.circuitTripTimeoutFactorSeconds=10
niws.loadbalancer.service-provider.circuitTripMaxTimeoutSeconds=30

​
public void updateListOfServers() {
    List<T> servers = new ArrayList<T>();
    if (serverListImpl != null) {
        servers = serverListImpl.getUpdatedListOfServers();
        LOGGER.debug("List of Servers for {} obtained from Discovery client: {}",
                getIdentifier(), servers);
        if (filter != null) {
            //通过指定NIWSServerListFilter过滤
            servers = filter.getFilteredListOfServers(servers);
            LOGGER.debug("Filtered List of Servers for {} obtained from Discovery client: {}",
                    getIdentifier(), servers);
        }
    }
    updateAllServerList(servers);
}
​

public ILoadBalancer ribbonLoadBalancer(IClientConfig config, ServerList<Server> serverList, ServerListFilter<Server> serverListFilter, IRule rule, IPing ping, ServerListUpdater serverListUpdater) {
        return (ILoadBalancer)(this.propertiesFactory.isSet(ILoadBalancer.class, this.name) ? (ILoadBalancer)this.propertiesFactory.get(ILoadBalancer.class, config, this.name) : new ZoneAwareLoadBalancer(config, rule, ping, serverList, serverListFilter, serverListUpdater));
    }

if (!ENABLED.get() || getLoadBalancerStats().getAvailableZones().size() <= 1) {
    logger.debug("Zone aware logic disabled or there is only one zone");
    return super.chooseServer(key);
}
Server server = null;
try {
    LoadBalancerStats lbStats = getLoadBalancerStats();
    Map<String, ZoneSnapshot> zoneSnapshot = ZoneAvoidanceRule.createSnapshot(lbStats);
    logger.debug("Zone snapshots: {}", zoneSnapshot);
    if (triggeringLoad == null) {
        triggeringLoad = DynamicPropertyFactory.getInstance().getDoubleProperty(
                "ZoneAwareNIWSDiscoveryLoadBalancer." + this.getName() + ".triggeringLoadPerServerThreshold", 0.2d);
    }
    if (triggeringBlackoutPercentage == null) {
        triggeringBlackoutPercentage = DynamicPropertyFactory.getInstance().getDoubleProperty(
                "ZoneAwareNIWSDiscoveryLoadBalancer." + this.getName() + ".avoidZoneWithBlackoutPercetage", 0.99999d);
    }
    Set<String> availableZones = ZoneAvoidanceRule.getAvailableZones(zoneSnapshot, triggeringLoad.get(), triggeringBlackoutPercentage.get());
    logger.debug("Available zones: {}", availableZones);
    if (availableZones != null &&  availableZones.size() < zoneSnapshot.keySet().size()) {
        //核心看这里，我们只要指定了zone，而不是随机，就能通过getLoadBalancer获取到对应zone的loadbalancer从而返回对应zone的实例
        String zone = ZoneAvoidanceRule.randomChooseZone(zoneSnapshot, availableZones);
        logger.debug("Zone chosen: {}", zone);
        if (zone != null) {
            BaseLoadBalancer zoneLoadBalancer = getLoadBalancer(zone);
            server = zoneLoadBalancer.chooseServer(key);
        }
    }
} catch (Exception e) {
    logger.error("Error choosing server using zone aware logic for load balancer={}", name, e);
}
if (server != null) {
    return server;
} else {
    logger.debug("Zone avoidance logic is not invoked.");
    return super.chooseServer(key);
}

package com.netflix.loadbalancer;
import com.netflix.client.config.IClientConfig;
import lombok.extern.log4j.Log4j2;
import org.apache.commons.lang.StringUtils;
@Log4j2
public class ZoneChosenLoadBalancer<T extends Server> extends ZoneAwareLoadBalancer {
    //通过ThreadLocal指定Zone，所以不能开启Hystrix
    //所以配置：feign.hystrix.enabled=false
    //开启hystrix会导致切换线程执行
    private static ThreadLocal<String> zoneThreadLocal = new ThreadLocal<>();
    public static void setZone(String zone) {
        zoneThreadLocal.set(zone);
    }
    
    public ZoneChosenLoadBalancer(IClientConfig clientConfig, IRule rule, IPing ping, ServerList serverList, ServerListFilter filter, ServerListUpdater serverListUpdater) {
        super(clientConfig, rule, ping, serverList, filter, serverListUpdater);
    }
    @Override
    public Server chooseServer(Object key) {
        try {
            String zone = zoneThreadLocal.get();
            if (StringUtils.isBlank(zone)) {
                log.info("zone is blank, use base loadbalancer");
                return super.chooseServer(key);
            }
            BaseLoadBalancer zoneLoadBalancer = getLoadBalancer(zone);
            Server server = zoneLoadBalancer.chooseServer(key);
            if (server != null) {
                return server;
            } else {
                log.info("server is null for zone {}, use base loadbalancer", zone);
                return super.chooseServer(key);
            }
        } finally {
            //无论如何都要remove
            zoneThreadLocal.remove();
        }
    }
}

import com.netflix.loadbalancer.MultiZoneLoadBalancerConfiguration;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Configuration;
@Configuration
//name对应要调用的微服务
@RibbonClient(name = "service-provider", configuration = MultiZoneLoadBalancerConfiguration.class)
public class ServiceScaffoldProviderLoadBalancerConfiguration {
}

package com.netflix.loadbalancer;
import com.netflix.client.config.IClientConfig;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MultiZoneLoadBalancerConfiguration {
    @Bean
    public ILoadBalancer ribbonLoadBalancer(IClientConfig config, ServerList<Server> serverList, ServerListFilter<Server> serverListFilter, IRule rule, IPing ping, ServerListUpdater serverListUpdater) {
        return new ZoneChosenLoadBalancer(config, rule, ping, serverList, serverListFilter, serverListUpdater);
    }
}

#关闭feign hystrix
feign.hystrix.enabled=false
#指定对应微服务的list不过滤
service-provider.ribbon.NIWSServerListFilterClassName=com.netflix.niws.loadbalancer.DefaultNIWSServerListFilter

eureka.instance.metadata-map.zone=myzone

eureka.client.availabilityZones.beijing=myzone # beijing是region

eureka.client.region=beijing

@Override
    public String[] getAvailabilityZones(String region) {
        String value = this.availabilityZones.get(region);
        if (value == null) {
            value = DEFAULT_ZONE;
        }
        return value.split(",");
    }