spring cloud整合feign和nacos报错：No Feign Client for loadBalancing defined. Did you forget to include

问题描述

最近在使用最新版本的nacos和feign的过程中，启动时遇到一个错误：

Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?

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百思不得其解，之前的spring cloud版本没有遇到这样的问题。花了将近几个小时，终于解决，记录一下，希望能给大家带来一点帮助。

项目环境

项目中的父pom文件版本依赖管理如下：

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.4</version>
    </parent>
     <properties>
        <spring-cloud.version>2020.0.2</spring-cloud.version>
    </properties>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--spring cloud -->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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用的是最新版本的springboot 和springcloud，然后在子项目中，我用到了feign和nacos，依赖如下：

 <dependencies>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        
         <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
 </dependencies>
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解决方案

1、引入eureka依赖——无效

第一时间想到的，spring cloud和springboot版本不兼容。查看spring cloud官网，发现spring boot版本号和spring cloud版本号可以对应：

说明项目是没问题的，就上网查找了一下，结果参考了这两位仁兄说的：

在项目中加入eureka依赖：

<dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>

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再次启动，报错：

Field autoServiceRegistration in org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration required a single bean, but 2 were found:
	- nacosAutoServiceRegistration: defined by method 'nacosAutoServiceRegistration' in class path resource [com/alibaba/cloud/nacos/registry/NacosServiceRegistryAutoConfiguration.class]
	- eurekaAutoServiceRegistration: defined by method 'eurekaAutoServiceRegistration' in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration.class]


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed


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这是因为项目中已经用到了nacos，再次引入eureka，会造成有两个注册中心的问题，说明这种解决方案无效。

2、降低spring cloud版本——无效

既然之前的版本没问题，那我就降级回去不就完事了，于是乎，我把项目的父pom中spring cloud版本降级到Hoxton SR1，spring boot版本也随之降级到2.2.1，即：

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
    </parent>
<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--spring cloud -->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>


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maven clean后再次启动，仍然报错：

错误信息：

Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?
	at org.springframework.cloud.openfeign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:333) ~[spring-cloud-openfeign-core-3.0.2.jar:3.0.2]
	at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:360) ~[spring-cloud-openfeign-core-3.0.2.jar:3.0.2]
	at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:339) ~[spring-cloud-openfeign-core-3.0.2.jar:3.0.2]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.lambda$registerFeignClient$0(FeignClientsRegistrar.java:230) ~[spring-cloud-openfeign-core-3.0.2.jar:3.0.2]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainFromSupplier(AbstractAutowireCapableBeanFactory.java:1231) ~[spring-beans-5.3.5.jar:5.3.5]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1173) ~[spring-beans-5.3.5.jar:5.3.5]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:564) ~[spring-beans-5.3.5.jar:5.3.5]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.5.jar:5.3.5]
	... 34 common frames omitted
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这次的错误信息跟第一次一样，可见降低版本这事已经行不通了，于是我复原了父pom。

3、添加ribbon——无效

在stackoverflow上看到了这两种解决方案：

因为不想在feign上加url，显得比较麻烦，于是我选择了第二种方案，加ribbon并配置了相关属性，启动还是报错：

Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?

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但是其中的第一种方案，我还是有点感兴趣，于是就根据第一种方案中的关键字spring-cloud-loadbalancer，搜索了一下。

4、加入spring-cloud-loadbalancer并在nacos中排除ribbon依赖——问题解决

继续搜索，发现如下结果：

根据这位大佬的说法，这是因为：

由于SpringCloud Feign在Hoxton.M2 RELEASED版本之后不再使用Ribbon而是使用spring-cloud-loadbalancer，所以不引入spring-cloud-loadbalancer会报错
解决方法
加入spring-cloud-loadbalancer依赖 并且在nacos中排除ribbon依赖，不然loadbalancer无效

问题突然有了点头目，于是乎，加入如下依赖：

//我是在这引入了spring-cloud-starter-alibaba-nacos-discovery
<dependency>
    <groupId>com.oyz.gulimall</groupId>
    <artifactId>gulimall-common</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </exclusion>
    </exclusions>
</dependency>
//加入spring-cloud-loadbalancer依赖


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

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之后，再次启动项目：

问题完美解决，还是得关注问题报错点：Did you forget to include spring-cloud-starter-loadbalancer，一开始没有注意到这个点，浪费了许多时间。

参考链接

1. Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined
2. stackoverflow
3. SpringCloud OpenFeign报错
4. No Feign Client for loadBalancing defined