关于ribbonClient配置的一个坑

序

不知道从哪个版本起(目测跟版本无关，应该是ribbon.eureka.enabled=true的情况下)，给ribbon配置物理的server list起，单纯配置xxx.ribbon.listOfServers不起效果了，于是就开启了埋坑之旅。

目前使用的是Camden.SR6版本

异常

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>)

复现条件

• 采用了RibbonClient来指定server list
• 没有使用@RibbonClients指定，把标注RibbonClient配置类放在了@ComponentScan扫描包下
• 有多个服务这样指定
• 而且其中还有一个服务使用load balanced restTemplate的时候，url中的服务名写错了，写成了一个不存在的服务名(当时是把外部的服务名改了导致的)

导致使用到了错误的server list。

问题配置

@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);
    }
}

这个的问题是把这个配置放到了@ComponentScan扫描的包下面
查看/beans

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

会发现多个ribbonClient的话，其中一个的ribbonServerList注册为全局的了。(为什么会注册为全局的？)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;
    }

这里发现已经有了ribbonServerList，而且没有找到指定的服务名的server list配置，于是就采用了全局的。

解决方案

解决方案很简单，就是修改为正确的服务名就可以了。另外一个方案就是不使用RibbonClient配置，最简单的就是配置文件添加NIWSServerListClassName属性：

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

规避全局ribbonServerList的方案

在不使用NIWSServerListClassName属性配置，使用RibbonClient配置的前提下，如何规避全局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);
    }
}

然后XxxRibbonConfig以及DemoRibbonConfig类上没有任何注解，比如

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);
    }
}

由于类上没有注解，因而这个时候就跟他们类路径是否在@ComponentScan扫描的包下面没有关系了。

方案2

把标注@RibbonClient的XxxRibbonConfig以及DemoRibbonConfig放到@ComponentScan扫描的包外面即可。