JHipster本地运行prod生产模式启动报8761连接被拒绝错误

问题现象 #

我是JHipster初学者，该框架可快速生成应用，我生成了一个简单单体应用，dev开发模式下运行完全正常，但使用./mvnw -Pprod命令启动生产模式时抛出错误，核心报错信息如下：

2022-06-30 14:52:30.639 ERROR 9088 --- [           main] o.s.boot.SpringApplication               : Application run failed
java.lang.IllegalStateException: Could not locate PropertySource and the fail fast property is set, failing
    at org.springframework.cloud.config.client.ConfigServicePropertySourceLocator.locate(ConfigServicePropertySourceLocator.java:148)
    at org.springframework.cloud.bootstrap.config.PropertySourceLocator.locateCollection(PropertySourceLocator.java:51)
    at org.springframework.cloud.config.client.ConfigServicePropertySourceLocator.locateCollection(ConfigServicePropertySourceLocator.java:160)
    at org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration.initialize(PropertySourceBootstrapConfiguration.java:95)
    at org.springframework.boot.SpringApplication.applyInitializers(SpringApplication.java:613)
    at org.springframework.boot.SpringApplication.prepareContext(SpringApplication.java:381)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:302)
    at com.sample.JtestingApp.main(JtestingApp.java:69)
Caused by: org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:8761/config/Jtesting/prod/main": Connection refused (Connection refused); nested exception is java.net.ConnectException: Connection refused (Connection refused)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:785)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:602)
    at org.springframework.cloud.config.client.ConfigServicePropertySourceLocator.getRemoteEnvironment(ConfigServicePropertySourceLocator.java:255)
    at org.springframework.cloud.config.client.ConfigServicePropertySourceLocator.locate(ConfigServicePropertySourceLocator.java:109)
    ... 7 common frames omitted
Caused by: java.net.ConnectException: Connection refused (Connection refused)
    at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412)
    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255)
    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237)
    at java.base/java.net.Socket.connect(Socket.java:609)
    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
    at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015)
    at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:776)
    ... 11 common frames omitted

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  03:53 min
[INFO] Finished at: 2022-06-30T14:52:30+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.6.6:run (default-cli) on project jtesting: Application finished with exit code: 1 -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.

报错根因为请求http://localhost:8761/config/Jtesting/prod/main时出现连接被拒绝异常，最终Maven构建失败。应用生成时的选型配置可参考附图，目前未修改任何代码，仅想对比dev与prod模式的运行差异，查阅资料后仍无法成功启动prod模式。

故障原因 #

生成应用时勾选了Spring Cloud相关组件，JHipster的prod模式默认开启Spring Cloud Config客户端的强制拉取配置逻辑：启动时必须从localhost:8761（JHipster Registry默认端口，同时承担注册中心、配置中心能力）拉取远程配置，且fail-fast参数默认为true，拉取失败直接终止启动。而dev模式默认关闭了强制拉取逻辑，因此可以正常启动。

解决方法 #

根据使用场景二选一即可：

• 仅本地测试prod模式，不需要使用注册中心/配置中心
  修改src/main/resources/config/application-prod.yml文件，找到Spring Cloud Config配置段，直接禁用配置中心能力即可，参考配置：

  spring:
    cloud:
      config:
        enabled: false
        fail-fast: false
        discovery:
          enabled: false
  

  保存后重新执行./mvnw -Pprod即可正常启动，无需额外依赖其他服务。
• 需要模拟完整生产架构运行
  先单独启动JHipster Registry服务，等待其完全启动、8761端口正常监听后，再执行./mvnw -Pprod启动单体应用，应用会自动从Registry拉取配置完成启动。

内容的提问来源于stack exchange，提问作者ZonG