聊聊如何独立使用ribbon实现业务客户端负载均衡

前言

ribbon是Netflix开源的客户端负载均衡工具，ribbon实现一系列的负载均衡算法，通过这些负载均衡算法去查找相应的服务。ribbon被大家所熟知，可能是来源于spring cloud，今天就来聊聊如何单独使用ribbon来实现业务客户端负载均衡

实现关键

springcloud ribbon获取服务列表是通过注册中心，而单独使用ribbon，因为没有注册中心加持，就得单独配置服务列表

示例

1、在业务项目中pom引入ribbon GAV

<dependency>
    <groupId>com.netflix.ribbon</groupId>
    <artifactId>ribbon</artifactId>
    <version>2.2.2</version>
</dependency>

不过引进去，发现如果引入netfiix的相关的类，比如IPing，会发现引不进去，原因是因为这个GAV里面依赖的jar的生命周期是runtime，即在运行期或者测试阶段才生效，在编译阶段是不生效的。如果我们为了方便，可以直接单独引入
spring cloud ribbon

    <dependency>
           <groupId>org.springframework.cloud</groupId>-->
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>-->
           <version>2.2.2.RELEASE</version>
    </dependency>

本文我们是想脱离springcloud，直接使用ribbon，因此我们可以直接 引入如下GAV

   <!--  核心的通用性代码-->
        <dependency>
            <groupId>com.netflix.ribbon</groupId>
            <artifactId>ribbon-core</artifactId>
            <version>${ribbon.version}</version>
        </dependency>
        <!-- 基于apache httpClient封装的rest客户端，集成了负载均衡模块，内嵌http心跳检测-->
        <dependency>
            <groupId>com.netflix.ribbon</groupId>
            <artifactId>ribbon-httpclient</artifactId>
            <version>${ribbon.version}</version>
        </dependency>
        <!-- 负载均衡模块-->
        <dependency>
            <groupId>com.netflix.ribbon</groupId>
            <artifactId>ribbon-loadbalancer</artifactId>
            <version>${ribbon.version}</version>
        </dependency>

        <!-- IClientConfig配置相关-->
        <dependency>
            <groupId>com.netflix.archaius</groupId>
            <artifactId>archaius-core</artifactId>
            <version>0.7.6</version>
        </dependency>

        <!-- IClientConfig配置相关-->
        <dependency>
            <groupId>commons-configuration</groupId>
            <artifactId>commons-configuration</artifactId>
            <version>1.8</version>
        </dependency>

2、创建ribbon元数据配置类

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class RuleDefinition {

    /**
     * 服务名称
     */
    private String serviceName;

    /**
     * 命名空间，当服务名相同时，可以通过namesapce来进行隔离区分
     * 未指定默认为public
     */
    @Builder.Default
    private String namespace = DEFAULT_NAMESPACE;

    /**
     * 自定义负载均衡策略，未指定默认为轮询
     */
    @Builder.Default
    private String loadBalancerRuleClassName = RoundRobin;

    /**
     * 自定义心跳检测，未指定不检测
     */
    @Builder.Default
    private String loadBalancerPingClassName = DummyPing;

    /**
     * 服务列表，多个用英文逗号隔开
     */
    private String listOfServers;


    /**
     * 该优先级大于loadBalancerPingClassName
     */
    private IPing ping;

    /**
     * 心跳间隔，不配置默认是10秒，单位秒
     */
    private int pingIntervalSeconds;


    /**
     * 该优先级大于loadBalancerRuleClassName
     */
    private IRule rule;



}

@Data
@AllArgsConstructor
@NoArgsConstructor
@ConfigurationProperties(prefix = PREFIX)
public class LoadBalanceProperty {

    public static final String PREFIX = "lybgeek.loadbalance";

    private List<RuleDefinition> rules;

    public Map<String,RuleDefinition> getRuleMap(){
        if(CollectionUtils.isEmpty(rules)){
            return Collections.emptyMap();
        }

        Map<String,RuleDefinition> ruleDefinitionMap = new LinkedHashMap<>();
        for (RuleDefinition rule : rules) {
            String key = rule.getServiceName() + RULE_JOIN + rule.getNamespace();
            ruleDefinitionMap.put(key,rule);
        }

        return Collections.unmodifiableMap(ruleDefinitionMap);
    }
}

3、创建负载均衡工厂【核心实现】

 private final LoadBalanceProperty loadBalanceProperty;

    // key:serviceName + nameSpace
    private static final Map<String, ILoadBalancer> loadBalancerMap = new ConcurrentHashMap<>();

    public ILoadBalancer getLoadBalancer(String serviceName,String namespace){
        String key = serviceName + RULE_JOIN + namespace;
        if(loadBalancerMap.containsKey(key)){
            return loadBalancerMap.get(key);
        }
        RuleDefinition ruleDefinition = getAvailableRuleDefinition(serviceName,namespace);
        IPing ping = ruleDefinition.getPing();
        if(ObjectUtils.isEmpty(ping)){
            // 无法通过ConfigurationManager.getConfigInstance().setProperty(serviceName + DOT + namespace + DOT + PING_CLASS_NAME, ruleDefinition.getLoadBalancerPingClassName());
            //LoadBalancerBuilder没提供通过ClientConfig配置ping方法，只能通过withPing修改
            ping = getPing(serviceName,namespace);
        }

        IRule rule = ruleDefinition.getRule();
        if(ObjectUtils.isEmpty(rule)){
            // 也可以通过ConfigurationManager.getConfigInstance().setProperty(serviceName + DOT + namespace + DOT + RULE_CLASS_NAME, ruleDefinition.getLoadBalancerRuleClassName());
            rule = getRule(serviceName,namespace);
        }


        // 配置服务列表
        ConfigurationManager.getConfigInstance().setProperty(serviceName + DOT + namespace + DOT + SERVER_LIST, ruleDefinition.getListOfServers());
        // 因为服务列表目前是配置写死，因此关闭列表更新，否则当触发定时更新时，会重新将服务列表状态恢复原样,这样会导致server的isLive状态不准确
        // 不设置默认采用com.netflix.loadbalancer.PollingServerListUpdater
        ConfigurationManager.getConfigInstance().setProperty(serviceName + DOT + namespace + DOT + SERVERLIST_UPDATER_CLASS_NAME, EmptyServerListUpdater.class.getName());
        IClientConfig config = new DefaultClientConfigImpl(namespace);
        config.loadProperties(serviceName);
        ZoneAwareLoadBalancer<Server> loadBalancer = getLoadBalancer(config, ping, rule);
        loadBalancerMap.put(key,loadBalancer);
        if(ruleDefinition.getPingIntervalSeconds() > 0){
            // 默认每隔10秒进行心跳检测
            loadBalancer.setPingInterval(ruleDefinition.getPingIntervalSeconds());
        }

        return loadBalancer;


    }



    public ZoneAwareLoadBalancer<Server> getLoadBalancer(IClientConfig config, IPing ping, IRule rule){
        ZoneAwareLoadBalancer<Server> serverZoneAwareLoadBalancer = LoadBalancerBuilder.newBuilder()
                .withClientConfig(config)
                .withPing(ping)
                .withRule(rule)
                .buildDynamicServerListLoadBalancerWithUpdater();
        return serverZoneAwareLoadBalancer;
    }






    /**
     * 获取 iping
     * @param serviceName
     * @param namespace
     * @return
     */
    @SneakyThrows
    public IPing getPing(String serviceName, String namespace){
        RuleDefinition ruleDefinition = getAvailableRuleDefinition(serviceName,namespace);
        Class<?> loadBalancerPingClass = ClassUtils.forName(ruleDefinition.getLoadBalancerPingClassName(), Thread.currentThread().getContextClassLoader());
        Assert.isTrue(IPing.class.isAssignableFrom(loadBalancerPingClass),String.format("loadBalancerPingClassName : [%s] is not Iping class type",ruleDefinition.getLoadBalancerPingClassName()));
        return (IPing) BeanUtils.instantiateClass(loadBalancerPingClass);


    }

    /**
     * 获取 loadbalanceRule
     * @param serviceName
     * @param namespace
     * @return
     */
    @SneakyThrows
    public IRule getRule(String serviceName, String namespace){
        RuleDefinition ruleDefinition = getAvailableRuleDefinition(serviceName,namespace);
        Class<?> loadBalancerRuleClass = ClassUtils.forName(ruleDefinition.getLoadBalancerRuleClassName(), Thread.currentThread().getContextClassLoader());
        Assert.isTrue(IRule.class.isAssignableFrom(loadBalancerRuleClass),String.format("loadBalancerRuleClassName : [%s] is not Irule class type",ruleDefinition.getLoadBalancerRuleClassName()));
        return (IRule) BeanUtils.instantiateClass(loadBalancerRuleClass);

    }

    private RuleDefinition getAvailableRuleDefinition(String serviceName,String namespace){
        Map<String, RuleDefinition> ruleMap = loadBalanceProperty.getRuleMap();
        Assert.notEmpty(ruleMap,"ruleDefinition is empty");
        String key = serviceName + RULE_JOIN + namespace;
        RuleDefinition ruleDefinition = ruleMap.get(key);
        Assert.notNull(ruleDefinition,String.format("NOT FOUND AvailableRuleDefinition with serviceName : [{}] in namespace:[{}]",serviceName,namespace));
        return ruleDefinition;
    }

核心实现类：com.netflix.loadbalancer.LoadBalancerBuilder 利用该类创建相应的负载均衡

4、测试

a、 新起2个服务提供者占用6666端口、和6667端口

b、 在消费端的application.yml配置如下内容

lybgeek:
  loadbalance:
    rules:
      - serviceName: provider
        namespace: test
        loadBalancerPingClassName: com.github.lybgeek.loadbalance.ping.TelnetPing
        pingIntervalSeconds: 3
     #   loadBalancerRuleClassName: com.github.lybgeek.loadbalance.rule.CustomRoundRobinRule
        listOfServers: 127.0.0.1:6666,127.0.0.1:6667

c、 测试类

  @Override
    public void run(ApplicationArguments args) throws Exception {

        ServerChooser serverChooser = ServerChooser.builder()
                .loadBalancer(loadbalanceFactory.getLoadBalancer("provider", "test"))
                .build();

        while(true){
            Server reachableServer = serverChooser.getServer("provider");
            if(reachableServer != null){
                System.out.println(reachableServer.getHostPort());
            }
            TimeUnit.SECONDS.sleep(1);

        }


    }

当服务提供者都正常提供服务时，观察控制台

可以观察以轮询的方式调用服务提供者，当断掉其中一台服务提供者时，再观察控制台

会发现只调用服务正常的那台

总结

独立使用ribbon其实不会很难，主要对LoadBalancerBuilder这个API熟悉就可以定制自己想要的负载均衡器。springcloud从2020版本就将ribbon废弃了，转而要扶持其亲儿子loadbalancer，就目前功能而言，loadbalancer还没ribbon丰富，通过本文纪念一下被springcloud遗弃的ribbon

demo链接

https://github.com/lyb-geek/springboot-learning/tree/master/springboot-ribbon-loadbalance