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Spring-Cloud-Ribbon學習筆記（二）：自定義負載均衡規則

本文轉載自   查看原文   2019-03-19 22:53   2364    spring-cloud/ spring-cloud-ribbon/ 負載均衡/ ribbon

Ribbon自定義負載均衡策略有兩種方式，一是JavaConfig，一是通過配置文件（yml或properties文件）。

需求

假設我有包含A和B服務在內的多個微服務，它們均注冊在一個Eureka上，信息如下：

我希望當訪問服務A時候，2個服務（端口分別是8087和8081）每兩次一換，比如訪問兩次8087，再訪問兩次8081，如此反復。
當訪問服務B時，與A類似，不過是3次一換。
當訪問其他服務時，采用隨機規則，即RandomRule，而不是默認策略[1]

JavaConfig

使用這種方式，總共分3步（以服務A的規則為例）：

  • 新建針對服務A的負載均衡規則類SvcARule，實現抽象類AbstractLoadBalancerRule並重寫方法，在類上只需要添加注解@Primary[2]，重寫邏輯須要根據實際需求來定，詳見下面的代碼
  • 新建配置類LBConfig，添加類型為IRule的Bean，此處我們選RandomRule
  • 在配置類LBConfig上,通過注解@RibbonClients（只有一種自定義規則，則使用@RibbonClient），添加不適用公共規則的其他自定義規則

實現

SvcARule

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;
import org.springframework.context.annotation.Primary;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Primary
public class SvcARule extends AbstractLoadBalancerRule {

    private AtomicInteger total = new AtomicInteger();
    private AtomicInteger index = new AtomicInteger();


    public Server choose(ILoadBalancer lb, Object key) {
        if (lb == null) {
            return null;
        }
        Server server = null;

        while (server == null) {
            if (Thread.interrupted()) {
                return null;
            }
            List<Server> upList = lb.getReachableServers();
            List<Server> allList = lb.getAllServers();

            int serverCount = allList.size();
            if (serverCount == 0) {
                return null;
            }
            if (total.get() < 2) {
                server = upList.get(index.get());
                total.incrementAndGet();
            } else {
                total.set(0);
                index.set(index.incrementAndGet() % upList.size());
            }

            if (server == null) {
                Thread.yield();
                continue;
            }

            if (server.isAlive()) {
                return (server);
            }

            server = null;
            Thread.yield();
        }
        return server;

    }

    @Override
    public Server choose(Object key) {
        return choose(getLoadBalancer(), key);
    }

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {
        // TODO Auto-generated method stub
    }
}

SvcBRule

略，只需要把if (total.get() < 2)改成if (total.get() < 3)即可

LBConfig

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import com.yan.ribbon.rule.SvcARule;
import com.yan.ribbon.rule.SvcBRule;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.cloud.netflix.ribbon.RibbonClients;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@RibbonClients(
        value = {
                @RibbonClient(name = "SVCA", configuration = SvcARule.class),
                @RibbonClient(name = "SVCB", configuration = SvcBRule.class)
        },
        defaultConfiguration = LBConfig.class)
public class LBConfig {
    @Bean
    public IRule commonRule() {
        return new RandomRule();
    }
}

測試

通過postman多次訪問服務A、B和C，得到日志如下：

2019-03-19 20:22:09.511  INFO 13372 --- [nio-8004-exec-4] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2019-03-19 20:22:09.511  INFO 13372 --- [nio-8004-exec-4] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2019-03-19 20:22:09.519  INFO 13372 --- [nio-8004-exec-4] o.s.web.servlet.DispatcherServlet        : Completed initialization in 8 ms
2019-03-19 20:22:09.693  INFO 13372 --- [nio-8004-exec-4] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-SVCA
2019-03-19 20:22:09.708  INFO 13372 --- [nio-8004-exec-4] c.netflix.loadbalancer.BaseLoadBalancer  : Client: SVCA instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCA,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2019-03-19 20:22:09.712  INFO 13372 --- [nio-8004-exec-4] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
2019-03-19 20:22:09.729  INFO 13372 --- [nio-8004-exec-4] c.n.l.DynamicServerListLoadBalancer      : DynamicServerListLoadBalancer for client SVCA initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCA,current list of Servers=[YanWei:8087, YanWei:8081],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;	Instance count:2;	Active connections count: 0;	Circuit breaker tripped count: 0;	Active connections per server: 0.0;]
},Server stats: [[Server:YanWei:8087;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
, [Server:YanWei:8081;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@7f0246c6
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8087===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
"svcA:8081===>\nname:xixi\ntype:haha"
2019-03-19 20:22:37.173  INFO 13372 --- [nio-8004-exec-5] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-SVCB
2019-03-19 20:22:37.174  INFO 13372 --- [nio-8004-exec-5] c.netflix.loadbalancer.BaseLoadBalancer  : Client: SVCB instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCB,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2019-03-19 20:22:37.177  INFO 13372 --- [nio-8004-exec-5] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
2019-03-19 20:22:37.178  INFO 13372 --- [nio-8004-exec-5] c.n.l.DynamicServerListLoadBalancer      : DynamicServerListLoadBalancer for client SVCB initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCB,current list of Servers=[YanWei:8086, YanWei:8082],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;	Instance count:2;	Active connections count: 0;	Circuit breaker tripped count: 0;	Active connections per server: 0.0;]
},Server stats: [[Server:YanWei:8082;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
, [Server:YanWei:8086;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@485ed210
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8082===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
"svcB:8086===>\nname:xixi\ntype:haha"
2019-03-19 20:23:01.319  INFO 13372 --- [nio-8004-exec-8] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-SVCC
2019-03-19 20:23:01.320  INFO 13372 --- [nio-8004-exec-8] c.netflix.loadbalancer.BaseLoadBalancer  : Client: SVCC instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCC,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2019-03-19 20:23:01.320  INFO 13372 --- [nio-8004-exec-8] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
2019-03-19 20:23:01.322  INFO 13372 --- [nio-8004-exec-8] c.n.l.DynamicServerListLoadBalancer      : DynamicServerListLoadBalancer for client SVCC initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=SVCC,current list of Servers=[YanWei:8083, YanWei:8085],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;	Instance count:2;	Active connections count: 0;	Circuit breaker tripped count: 0;	Active connections per server: 0.0;]
},Server stats: [[Server:YanWei:8083;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
, [Server:YanWei:8085;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 08:00:00 CST 1970;	First connection made: Thu Jan 01 08:00:00 CST 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@77b35c9
"svcC:8085===>\nname:xixi\ntype:haha"
"svcC:8083===>\nname:xixi\ntype:haha"
"svcC:8085===>\nname:xixi\ntype:haha"
"svcC:8085===>\nname:xixi\ntype:haha"
"svcC:8083===>\nname:xixi\ntype:haha"
"svcC:8085===>\nname:xixi\ntype:haha"
"svcC:8085===>\nname:xixi\ntype:haha"

配置文件方式

配置文件方式須要遵守以下格式：

<serviceName>.ribbon.<key>=<value>

幾個變量解釋如下：

serviceName就是服務名
key是指Ribbon為實現不同領域（我們這里只說IRule，其實還有IPing等）所指定的關聯類名，這里我需要自定義IRule，其關聯類名，也就是所謂的key，是NFLoadBalancerRuleClassName[3]
value是我所要指定的自定義規則，比如，SvcB的負載均衡策略SvcBRule

因此，在配置文件中添加如下配置:

svcB:
  ribbon:
    NFLoadBalancerRuleClassName: com.yan.ribbon.rule.SvcBRule

重新啟動Ribbon服務后，發現此配置並沒有生效，原因有兩個：
一是我的服務名字寫的是svcB，理由是我的配置spring.appliaction.name=svcB，但是使用Ribbon調用時使用了http://SVCB/...，SVCB是大寫的，所以沒有得到期望的效果[4]
二是我已經有了用來替換默認規則的LBConfig，使得IRule的默認配置沒有生效，因為查看源碼org.springframework.cloud.netflix.ribbon.RibbonClientConfiguration中對於IRule的定義如下：

	@Bean
	@ConditionalOnMissingBean
	public IRule ribbonRule(IClientConfig config) {
		if (this.propertiesFactory.isSet(IRule.class, name)) {
			return this.propertiesFactory.get(IRule.class, config, name);
		}
		ZoneAvoidanceRule rule = new ZoneAvoidanceRule();
		rule.initWithNiwsConfig(config);
		return rule;
	}

由於我自定義的commonRule已經存在了，所以此處不會觸發，更不會走到判斷那一步，就是說，我的上面的關於SvcB的自定義規則的配置，是沒有什么地方去讀的，因此，為了方便演示，直接將LBConfig全部注掉，再次重啟后，把訪問Uri中的大寫改成一致的svcB，發現對於服務B的配置生效了，但是沒有指定的服務，全部都采用了默認的策略ZoneAvoidanceRule。

總結

配置文件方式，比較麻煩，且不能-沒必要也懶得研究如何-修改默認規則，而JavaConfig可以完美替代，因此我選JavaConfig。

進階

關於Ribbon中對於IRule的實現，總共有如下幾種，其簡略說明也附注如下：

  • RoundRobinRule: 輪詢
  • RandomRule：隨機
  • AvailabilityFilteringRule：會先過濾掉由於多次訪問故障而處於斷路器跳閘狀態的服務，還有並發的連接數超過閾值的服務，然后對剩余的服務列表按照輪詢策略進行訪問
  • WeightedResponseTimeRule：根據平均響應時間計算所有服務的權重，響應時間越快服務權重越大，被選中的概率越高。剛啟動時如果統計信息不足，則使用RoundRobinRule策略，等統計信息足夠，會切換到WeightedResponseTimeRule
  • RetryRule: 先按照RoundRobinRule的策略獲取服務，如果獲取服務失敗，則在指定時間內會進行重試，獲取可用服務
  • BestAvailableRule: 會先過濾掉由於多次訪問故障而處於斷路器跳閘狀態的服務，然后選擇一個並發量最小的服務
  • ZoneAvoidanceRule: 默認規則，符合判斷server所在區域的性能和server的可用性選擇服務器

  1. 對應類為ZoneAvoidanceRule，直譯過來是區域回避規則，我也不知道為啥這樣叫:D ↩︎

  2. 如果不加此注解，會報錯，內容是找類型為IRule的Bean，但是找到了倆，一個commonRule，一個svcARule。如果你不嫌麻煩，可以選擇網上流行的較為復雜的形式，比如springcloud-04-自定義ribbon的配置方式 ↩︎

  3. 可以在類org.springframework.cloud.netflix.ribbon.PropertiesFactory中查看 ↩︎

  4. 這個Eureka也要背鍋，因為使用服務名來進行服務間調用，是被大小寫是被兼容過的，導致我這邊疏忽大意了，還是要細心的好。 ↩︎


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