Vaadin 14+SpringBoot生产模式启动后访问报500内部错误

问题描述 #

基于SpringBoot的Vaadin 14网站已切换至生产模式，Tomcat启动正常，但首次通过浏览器访问时出现500内部服务器错误，显示白标错误页面，核心异常为无法读取webpack生成的stats.json文件，提示生产模式下需确认build-frontend任务执行成功且该文件在类路径中，或切换至开发模式。

完整异常栈：

白标错误页面
此应用未配置/error的显式映射，因此显示此回退页面。
2022年8月30日 星期二 11:11:55 CEST
发生意外错误（类型=内部服务器错误，状态=500）。
com.vaadin.flow.server.BootstrapException: Unable to read webpack stats file.
com.vaadin.flow.server.ServiceException: com.vaadin.flow.server.BootstrapException: Unable to read webpack stats file.
at com.vaadin.flow.server.VaadinService.handleExceptionDuringRequest(VaadinService.java:1594)
at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1557)
at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:247)
at com.vaadin.flow.spring.SpringServlet.service(SpringServlet.java:108)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:352)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312)
at org.springframework.web.servlet.mvc.ServletForwardingController.handleRequestInternal(ServletForwardingController.java:141)
at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:177)
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:52)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
Caused by: com.vaadin.flow.server.BootstrapException: Unable to read webpack stats file.
at com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.setupFrameworkLibraries(BootstrapHandler.java:893)
at com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.setupDocumentHead(BootstrapHandler.java:770)
at com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.getBootstrapPage(BootstrapHandler.java:539)
at com.vaadin.flow.server.BootstrapHandler.synchronizedHandleRequest(BootstrapHandler.java:480)
at com.vaadin.flow.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1545)
... 52 more
Caused by: java.io.IOException: The stats file from webpack (stats.json) was not found.
The application is running in production mode.Verify that build-frontend task has executed successfully and that stats.json is on the classpath.Or switch application to development mode.
at com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.appendNpmBundle(BootstrapHandler.java:925)
at com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.setupFrameworkLibraries(BootstrapHandler.java:891)
... 57 more

项目配置信息 #

<properties>
    <java.version>1.8</java.version>
    <vaadin.version>14.8.16</vaadin.version>
    <!-- 执行"java -jar"时启动的主类 -->
    <start-class>com.rofu.onlinestatistikcenter.Application</start-class>
</properties>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.6.7</version>
</parent>

解决方案 #

• 手动执行前端构建任务：在项目根目录运行以下Maven命令，生成前端资源及stats.json文件：

  mvn vaadin:build-frontend
  

• 自动绑定构建任务到打包阶段：修改pom.xml，让build-frontend任务在package阶段自动执行，确保打包jar/war时已生成前端资源：

  <build>
      <plugins>
          <plugin>
              <groupId>com.vaadin</groupId>
              <artifactId>vaadin-maven-plugin</artifactId>
              <version>${vaadin.version}</version>
              <executions>
                  <execution>
                      <goals>
                          <goal>build-frontend</goal>
                      </goals>
                      <phase>package</phase>
                  </execution>
              </executions>
          </plugin>
      </plugins>
  </build>
  

• 临时切换到开发模式（仅调试用）：在application.properties中添加以下配置，开发模式下Vaadin会自动处理前端资源，无需提前构建，但禁止用于生产环境：

  vaadin.productionMode=false
  

内容的提问来源于stack exchange，提问作者Till Glückner