關於ribbonClient配置的一個坑

序

不知道從哪一個版本起(目測跟版本無關，應該是ribbon.eureka.enabled=true的狀況下)，給ribbon配置物理的server list起，單純配置xxx.ribbon.listOfServers不起效果了，因而就開啓了埋坑之旅。

目前使用的是Camden.SR6版本

異常

java.lang.IllegalStateException: No instances available for xxx
    at org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient.execute(RibbonLoadBalancerClient.java:75)
    at org.springframework.cloud.client.loadbalancer.LoadBalancerInterceptor.intercept(LoadBalancerInterceptor.java:53)
    at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:86)
    at org.springframework.cloud.netflix.metrics.MetricsClientHttpRequestInterceptor.intercept(MetricsClientHttpRequestInterceptor.java:68)
    at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:86)
    at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:70)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:652)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:613)
    at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:407)
    at org.springframework.web.client.RestTemplate$$FastClassBySpringCGLIB$$aa4e9ed0.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:721)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85)
    at org.springframework.cloud.netflix.metrics.RestTemplateUrlTemplateCapturingAspect.captureUrlTemplate(RestTemplateUrlTemplateCapturingAspect.java:33)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:629)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:618)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:656)
    at org.springframework.web.client.RestTemplate$$EnhancerBySpringCGLIB$$ec1f757d.postForEntity(<generated>)

復現條件

• 採用了RibbonClient來指定server list
• 沒有使用@RibbonClients指定，把標註RibbonClient配置類放在了@ComponentScan掃描包下
• 有多個服務這樣指定
• 並且其中還有一個服務使用load balanced restTemplate的時候，url中的服務名寫錯了，寫成了一個不存在的服務名(當時是把外部的服務名改了致使的)

致使使用到了錯誤的server list。

問題配置

@RibbonClient(name = "xxx",configuration = XxxRibbonConfig.class)
public class XxxRibbonConfig {

    String listOfServers = "http://192.168.99.100:8080,http://192.168.99.101:8080";

    @Bean
    public ServerList<Server> ribbonServerList() {
        List<Server> list = Lists.newArrayList();
        if (!Strings.isNullOrEmpty(listOfServers)) {
            for (String s: listOfServers.split(",")) {
                list.add(new Server(s.trim()));
            }
        }
        return new StaticServerList<Server>(list);
    }
}

這個的問題是把這個配置放到了@ComponentScan掃描的包下面

查看/beans

{
"bean": "ribbonServerList",
"aliases": [],
"scope": "singleton",
"type": "org.springframework.cloud.netflix.ribbon.StaticServerList",
"resource": "class path resource [com/xxx/XxxRibbonConfig.class]",
"dependencies": []
}

會發現多個ribbonClient的話，其中一個的ribbonServerList註冊爲全局的了。(爲何會註冊爲全局的？)而spring-cloud-netflix-core-1.2.6.RELEASE-sources.jar!/org/springframework/cloud/netflix/ribbon/RibbonClientConfiguration.java

@Bean
    @ConditionalOnMissingBean
    @SuppressWarnings("unchecked")
    public ServerList<Server> ribbonServerList(IClientConfig config) {
        if (this.propertiesFactory.isSet(ServerList.class, name)) {
            return this.propertiesFactory.get(ServerList.class, config, name);
        }
        ConfigurationBasedServerList serverList = new ConfigurationBasedServerList();
        serverList.initWithNiwsConfig(config);
        return serverList;
    }

這裏發現已經有了ribbonServerList，並且沒有找到指定的服務名的server list配置，因而就採用了全局的。

解決方案

解決方案很簡單，就是修改成正確的服務名就能夠了。另一個方案就是不使用RibbonClient配置，最簡單的就是配置文件添加NIWSServerListClassName屬性：

xxx:
  ribbon:
    ReadTimeout: 60000
    ConnectTimeout: 60000
      NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
      listOfServers: http://192.168.99.100:8080,http://192.168.99.101:8080

規避全局ribbonServerList的方案

在不使用NIWSServerListClassName屬性配置，使用RibbonClient配置的前提下，如何規避全局ribbonServerList呢？

方案1：使用@RibbonClients配置

@SpringCloudApplication
@RibbonClients(value = {
        @RibbonClient(name = "xxx",configuration = XxxRibbonConfig.class),
        @RibbonClient(name = "demo",configuration = DemoRibbonConfig.class)
})
public class DemoServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoServiceApplication.class, args);
    }
}

而後XxxRibbonConfig以及DemoRibbonConfig類上沒有任何註解，好比

public class XxxRibbonConfig {

    String listOfServers = "http://192.168.99.100:8080,http://192.168.99.101:8080";

    @Bean
    public ServerList<Server> ribbonServerList() {
        List<Server> list = Lists.newArrayList();
        if (!Strings.isNullOrEmpty(listOfServers)) {
            for (String s: listOfServers.split(",")) {
                list.add(new Server(s.trim()));
            }
        }
        return new StaticServerList<Server>(list);
    }
}

因爲類上沒有註解，於是這個時候就跟他們類路徑是否在@ComponentScan掃描的包下面沒有關係了。

方案2

把標註@RibbonClient的XxxRibbonConfig以及DemoRibbonConfig放到@ComponentScan掃描的包外面便可。