通过启用功能区的客户端调用微服务时失败（没有尤里卡服务发现）

Question

我正在尝试通过功能区启用客户端 (ribbon-client) 调用 'microservice'(microservice-producer)，但它给我一个错误。

java.lang.IllegalStateException: No instances available for employee-microservice

我正在遵循客户端负载平衡的官方 spring.io link(https://spring.io/guides/gs/client-side-load-balancing/)，并且我还遵循此 link 给出的所有规范。你可以在我的 GitHub 地址看到代码： (https://github.com/vickygupta0017/microservice-ribbon).

我不确定我遗漏了什么或做错了什么，有人可以帮我吗？

Answer 1

Ribbon Client 的配置不正确，我在 Ribbon Client 中通过以下更改成功执行了代码，在客户端调用时它抛出了 Null Pointer Exception，因为 Ribbon Client 的几个参数没有成功设置，我可以请参阅 EmployeeConfiguration Class 中缺少 @Configuration，因此它将如何初始化 Ribbon 客户端。

还在以下位置检查了完整的可用代码：

https://github.com/abhayjohri87/RibbonClientLBWithMicroServices.git

package com.ribbon.client;
import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.netflix.client.config.DefaultClientConfigImpl;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.ConfigurationBasedServerList;
import com.netflix.loadbalancer.Server;
import com.netflix.loadbalancer.ServerList;
//import com.ribbon.Employee.configuration.EmployeeConfiguration;
import com.ribbon.client.RibbonClientApplication.UserConfig;


@SpringBootApplication
@RestController
@RibbonClient(name = "employee-microservice", configuration = UserConfig.class)
public class RibbonClientApplication {

      @LoadBalanced
      @Bean
      RestTemplate restTemplate(){
        return new RestTemplate();
      }

      @Autowired
      RestTemplate restTemplate;

      @RequestMapping("/listEmployee")
      public List getEmployeeList() {
        List empList = this.restTemplate.getForObject("http://employee-microservice/employees", ArrayList.class);
        return empList;
      }

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


    @Configuration
    static class UserConfig {

        private String name = "employee-microservice";

        @Bean
        @ConditionalOnMissingBean
        public IClientConfig ribbonClientConfig() {
            DefaultClientConfigImpl config = new DefaultClientConfigImpl();
            config.loadProperties(this.name);
            return config;
        }

        @Bean
        ServerList<Server> ribbonServerList(IClientConfig config) {
            ConfigurationBasedServerList serverList = new ConfigurationBasedServerList();
            serverList.initWithNiwsConfig(config);
            return serverList;
        }

    }
}

Answer 2

在不使用 eureka 服务器来识别服务器是否可达的情况下，ribbon 客户端使用 "RibbonConfiguration" - pingUrl 参数。默认情况下，它是空字符串，这意味着它将在没有任何上下文的情况下 ping 服务器列表以获取服务器是否可达的答案。所以在这里你可以做两件事。

创建绑定到服务器“/”的根上下文的服务并发送肯定响应。

@RequestMapping(value = "/")
public String status(HttpServletRequest request) {
    return "";
}

或者用相关的"service-name".

更新Ribbon客户端配置(EmployeeConfiguration)和returnPingUrl

@Bean
public IPing ribbonPing(IClientConfig config) {
   return new PingUrl(false,"/employees");
}

选择第一个，因为它将解决查看服务器是否可达的基本目的。

参考：https://spring.io/guides/gs/client-side-load-balancing/

Our IPing is a PingUrl, which will ping a URL to check the status of each server. Say Hello has, as you’ll recall, a method mapped to the / path; that means that Ribbon will get an HTTP 200 response when it pings a running Say Hello server. The IRule we set up, the AvailabilityFilteringRule, will use Ribbon’s built-in circuit breaker functionality to filter out any servers in an “open-circuit” state: if a ping fails to connect to a given server, or if it gets a read failure for the server, Ribbon will consider that server “dead” until it begins to respond normally.

通过启用功能区的客户端调用微服务时失败（没有尤里卡服务发现）

Failure while calling a microservice via ribbon enabled client(Without eureka service discovery)

java

microservices

netflix-ribbon