处理SpringCloudConfig客户端启动无法读取到配置参数

自己部署了一个Spring Cloud微服务项目，实践Spring Cloud Config分布式配置组件，按照Spring Cloud Config 资料Config：Spring Cloud分布式配置组件 先后创建了Eureka注册中心服务、 Spring Cloud Config Server服务、 Spring Cloud Config Client客户端，在最后启动 Spring Client Config Client 客户端时，客户端始终无法访问 Config Server服务，读取上传在Gitee上的配置文件的内容。

在Baidu、 Google搜索了大量资料，问题是最终解决了，但是这其中的原因，还需要继续探讨。

Eureka注册中心和Spring Cloud Config Server的配置内容就不多讲，可参考Eureka：Spring Cloud服务注册与发现组件 和Config：Spring Cloud分布式配置组件，启动了 Config Server 服务，并用浏览器访问，上传在Gitee上的参数文件的内容是可以正常获取到的

我们重点说一下Spring Cloud Config Client的配置，yml文件配置如下：

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server:
  port: 3355 #端口号
spring:
  application:
    name: spring-cloud-config-client #服务名
  cloud:
    config:
      label: master #分支名称
      name: application  #配置文件名称，application-dev.yml 中的 config
      profile: dev  #环境名  application-dev.yml 中的 dev
      #这里不要忘记添加 http:// 否则无法读取
      uri: http://localhost:3344 #Spring Cloud Config 服务端（配置中心）地址

eureka:
  client: #将客户端注册到 eureka 服务列表内
    service-url:
      defaultZone: http://localhost:9900/eureka

新增Controller类，用于测试配置文件内容的读取

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@RestController
@RequestMapping("/config/client")
public class ConfigClientController {

    @Value("${server.port}")
    private String serverPort;

    @Value("${config.info}")
    private String configInfo;

    @Value("${config.version}")
    private String configVersion;

    @GetMapping(value = "/getConfig")
    public String getConfig() {
        return "info：" + configInfo + "<br/>version：" 
        	+ configVersion + "<br/>port：" + serverPort;
    }

}

Spring Cloud Config Client客户端在启动的时候控制台报错：

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Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'config.info' in value "${config.info}"
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:180) ~[spring-core-5.3.23.jar:5.3.23]
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-5.3.23.jar:5.3.23]
	at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239) ~[spring-core-5.3.23.jar:5.3.23]
	at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-5.3.23.jar:5.3.23]
	at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.lambda$processProperties$0(PropertySourcesPlaceholderConfigurer.java:191) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:936) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1332) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1311) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.23.jar:5.3.23]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.23.jar:5.3.23]
	... 16 common frames omitted

Disconnected from the target VM, address: '127.0.0.1:54601', transport: 'socket'

Process finished with exit code 1

遂检查配置文件，对照资料教程看是不是自己写错了。在检查 Config Client 模块的配置文件时发现，资料上创建的配置文件名称是 bootstrap.yml 而非 application.yml

遂把配置文件名改为 bootstrap.yml， 重新启动，发现没有报之前的错误了。但是服务也没有正常运行起来，而是直接停止了，控制台输出：

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2023-02-01 20:42:52.002  INFO 15096 --- [           main] com.netflix.discovery.DiscoveryClient    : Starting heartbeat executor: renew interval is: 30
2023-02-01 20:42:52.005  INFO 15096 --- [           main] c.n.discovery.InstanceInfoReplicator     : InstanceInfoReplicator onDemand update allowed rate per min is 4
2023-02-01 20:42:52.012  INFO 15096 --- [           main] com.netflix.discovery.DiscoveryClient    : Discovery Client initialized at timestamp 1675255372011 with initial instances count: 2
2023-02-01 20:42:52.015  INFO 15096 --- [           main] o.s.c.n.e.s.EurekaServiceRegistry        : Registering application SPRING-CLOUD-CONFIG-CLIENT with eureka with status UP
2023-02-01 20:42:52.016  INFO 15096 --- [           main] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1675255372016, current=UP, previous=STARTING]
2023-02-01 20:42:52.018  INFO 15096 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355: registering service...
2023-02-01 20:42:52.033  INFO 15096 --- [           main] c.s.c.ConfigClientApplication            : Started ConfigClientApplication in 10.224 seconds (JVM running for 10.92)
2023-02-01 20:42:52.040  INFO 15096 --- [ionShutdownHook] o.s.c.n.e.s.EurekaServiceRegistry        : Unregistering application SPRING-CLOUD-CONFIG-CLIENT with eureka with status DOWN
2023-02-01 20:42:52.040  INFO 15096 --- [ionShutdownHook] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1675255372040, current=DOWN, previous=UP]
2023-02-01 20:42:52.042  INFO 15096 --- [ionShutdownHook] com.netflix.discovery.DiscoveryClient    : Shutting down DiscoveryClient ...
2023-02-01 20:42:52.076  INFO 15096 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355 - registration status: 204
2023-02-01 20:42:52.077  INFO 15096 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355: registering service...
2023-02-01 20:42:52.080  INFO 15096 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355 - registration status: 204
2023-02-01 20:42:52.081  INFO 15096 --- [ionShutdownHook] com.netflix.discovery.DiscoveryClient    : Unregistering ...
2023-02-01 20:42:52.085  INFO 15096 --- [ionShutdownHook] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355 - deregister  status: 200
2023-02-01 20:42:52.091  INFO 15096 --- [ionShutdownHook] com.netflix.discovery.DiscoveryClient    : Completed shut down of DiscoveryClient
Disconnected from the target VM, address: '127.0.0.1:58233', transport: 'socket'

Process finished with exit code 0

其中有一句 Registering application SPRING-CLOUD-CONFIG-CLIENT with eureka with status UP，

查询资料，在这篇文章SpringCloud中Client向Eureka注册中心注册服务成功后不久就Unregistering（Unregistering application 服务名 with eureka with）中有提出解决办法

虽然 Config Client 子模块依赖的父模块中，pom文件已经引入了spring-boot-web 依赖，但是依旧要在 Config Client 子模块的pom文件上加上 spring-boot-web 依赖 

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<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

再次启动，服务启动成功

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23-02-01 20:51:37.092  INFO 16848 --- [           main] c.n.discovery.InstanceInfoReplicator     : InstanceInfoReplicator onDemand update allowed rate per min is 4
2023-02-01 20:51:37.098  INFO 16848 --- [           main] com.netflix.discovery.DiscoveryClient    : Discovery Client initialized at timestamp 1675255897097 with initial instances count: 1
2023-02-01 20:51:37.100  INFO 16848 --- [           main] o.s.c.n.e.s.EurekaServiceRegistry        : Registering application SPRING-CLOUD-CONFIG-CLIENT with eureka with status UP
2023-02-01 20:51:37.100  INFO 16848 --- [           main] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1675255897100, current=UP, previous=STARTING]
2023-02-01 20:51:37.103  INFO 16848 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355: registering service...
2023-02-01 20:51:37.138  INFO 16848 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 3355 (http) with context path ''
2023-02-01 20:51:37.139  INFO 16848 --- [           main] .s.c.n.e.s.EurekaAutoServiceRegistration : Updating port to 3355
2023-02-01 20:51:37.164  INFO 16848 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRING-CLOUD-CONFIG-CLIENT/DESKTOP-A5PHDVG:spring-cloud-config-client:3355 - registration status: 204
2023-02-01 20:51:38.241  INFO 16848 --- [           main] c.s.c.ConfigClientApplication            : Started ConfigClientApplication in 12.417 seconds (JVM running for 13.157)

Eureka注册中心

浏览器调用接口

那么，为什么Spring Cloud Config Client 的配置文件为什么要用 bootstrap.yml， 而不是 application ？ 这里有一篇文章有说明SpringCloud Config - client连接server的设置写在application.yml, 导致属性无法解析

Bootstrap.yml (bootstrap.properties) 是在application.yml (application.properties)之前加载的。它通常用于“使用SpringCloud Config Server时，应在bootstrap.yml中指定spring.application.name和spring.cloud.config.server.git.uri”以及一些加密/解密信息。

Spring Cloud会创建一个Bootstrap Context（由bootstrap.yml加载），作为Spring应用的Application Context（由application.yml加载）的父上下文。初始化的时候，Bootstrap Context负责从外部源加载配置属性并解析配置。这两个上下文共享一个从外部获取的Environment。Bootstrap属性有高优先级，默认情况下，它们不会被本地配置覆盖。

例如，当使用SpringCloud Config时，通常从服务器加载“真正的”配置数据。为了获取URL（和其他连接配置，如密码等），您需要一个较早的或“bootstrap”配置。因此，您将配置服务器属性放在bootstrap.yml中，该属性用于加载实际配置数据（通常覆盖application.yml [如果存在]中的内容）。

补充：

在刚开始启动Spring Cloud Config Client 时，控制台提示：

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Description:

No spring.config.import property has been defined

Action:

Add a spring.config.import=configserver: property to your configuration.
	If configuration is not required add spring.config.import=optional:configserver: instead.
	To disable this check, set spring.cloud.config.enabled=false or 
	spring.cloud.config.import-check.enabled=false.

Disconnected from the target VM, address: '127.0.0.1:58966', transport: 'socket'

Process finished with exit code 1

stackoverflow上有篇文章No spring.config.import property has been defined中给出解决办法，在pom文件中加上依赖

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