Spring Boot3.0.0+Spring Cloud2021.0.5 Feign负载均衡缺失问题求助

使用环境：Spring Boot 3.0.0 + Spring Cloud 2021.0.5

现有BillingServiceApplication.java代码：

package org.sid.billingservice;

import org.sid.billingservice.entities.Bill;
import org.sid.billingservice.entities.ProductItem;
import org.sid.billingservice.model.Customer;
import org.sid.billingservice.model.Product;
import org.sid.billingservice.repository.BillRepository;
import org.sid.billingservice.repository.ProductItemRepository;
import org.sid.billingservice.services.CustomerRestClient;
import org.sid.billingservice.services.ProductRestClient;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.ImportAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.cloud.openfeign.FeignAutoConfiguration;
import org.springframework.context.annotation.Bean;

import java.util.Collection;
import java.util.Date;
import java.util.Random;

@SpringBootApplication
@EnableFeignClients
@ImportAutoConfiguration({FeignAutoConfiguration.class})
public class BillingServiceApplication {

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

    @Bean
    CommandLineRunner start(BillRepository billRepository, ProductItemRepository productItemRepository, CustomerRestClient customerRestClient, ProductRestClient productRestClient) {
        return args -> {
            Collection<Product> products = productRestClient.allProducts().getContent();
            Long customerId = 1L;
            Customer customer = customerRestClient.findCustomerById(customerId);
            if (customer == null) throw new RuntimeException("Customer not found");
            Bill bill = new Bill();
            bill.setBillDate(new Date());
            bill.setCustomerId(customerId);
            Bill savedBill = billRepository.save(bill);
            products.forEach(product -> {
                ProductItem productItem = new ProductItem();
                productItem.setBill(savedBill);
                productItem.setProductId(product.getId());
                productItem.setQuantity(1 + new Random().nextInt(10));
                productItem.setPrice(product.getPrice());
                productItem.setDiscount(Math.random());
                productItemRepository.save(productItem);
            });
        };
    }

}

运行时抛出错误：

No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?

完整错误日志包含该错误及相关调用栈信息。

1. 添加Spring Cloud LoadBalancer依赖 #

Spring Cloud 2021.0.x版本开始，Feign不再默认集成Ribbon，需要手动引入Spring Cloud LoadBalancer作为负载均衡组件。

• Maven（pom.xml）：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>

• Gradle（build.gradle）：

implementation 'org.springframework.cloud:spring-cloud-starter-loadbalancer'

2. 移除冗余配置 #

删除类上的@ImportAutoConfiguration({FeignAutoConfiguration.class})注解，因为@EnableFeignClients已经自动完成Feign相关配置的导入，手动导入会导致配置冲突。

修改后的类注解部分：

@SpringBootApplication
@EnableFeignClients
public class BillingServiceApplication {
    // ... 原有代码
}

3. 确认Feign客户端接口配置 #

确保你的CustomerRestClient和ProductRestClient接口正确使用@FeignClient注解指定服务名称，示例：

@FeignClient(name = "customer-service") // 对应注册中心的客户服务名称
public interface CustomerRestClient {
    @GetMapping("/customers/{id}")
    Customer findCustomerById(@PathVariable Long id);
}

@FeignClient(name = "product-service") // 对应注册中心的产品服务名称
public interface ProductRestClient {
    @GetMapping("/products")
    Page<Product> allProducts();
}

完成以上步骤后，重新启动服务即可解决该错误。

内容的提问来源于stack exchange，提问作者Đỗ Như Vỹ