Google App Engine deployments causes NPE

[dmitrilc]

Description of the bug

After deploying the starter Vaadin Start project to Google App Engine, the error below is thrown when accessed from the client side.

java.lang.NullPointerException: Cannot invoke "java.io.RandomAccessFile.length()" because "this.cache" is null
	at java.desktop/javax.imageio.stream.FileCacheImageOutputStream.close(FileCacheImageOutputStream.java:229) ~[na:na]
	at java.desktop/javax.imageio.ImageIO.write(ImageIO.java:1598) ~[na:na]
	at com.vaadin.flow.server.PwaIcon.setImage(PwaIcon.java:220) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.PwaRegistry.initializeIcons(PwaRegistry.java:170) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.PwaRegistry.<init>(PwaRegistry.java:136) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.PwaRegistry.getInstance(PwaRegistry.java:324) ~[flow-server-23.1.2.jar!/:23.1.2]
	at java.base/java.util.Optional.map(Optional.java:260) ~[na:na]
	at com.vaadin.flow.server.VaadinServletService.getPwaRegistry(VaadinServletService.java:233) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.VaadinService.lambda$createRequestHandlers$20741bb$1(VaadinService.java:330) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.communication.PwaHandler.handleRequest(PwaHandler.java:131) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1564) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:299) ~[flow-server-23.1.2.jar!/:23.1.2]
	at com.vaadin.flow.spring.SpringServlet.service(SpringServlet.java:109) ~[vaadin-spring-23.1.2.jar!/:na]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:711) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:353) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:313) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.springframework.web.servlet.mvc.ServletForwardingController.handleRequestInternal(ServletForwardingController.java:141) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:177) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:51) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1787) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.64.jar!/:na]
	at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

Expected behavior

The app should not have thrown an exception.

Minimal reproducible example

Attached Vaadin Start project small-vaadin-app with yaml.zip

Deployment steps with instructions from https://vaadin.com/docs/latest/production/cloud-providers/google:

1. Build jar mvn package -Pproduction

2. Init project gcloud init

3. Create instance gcloud app create

4. Deploy app. gcloud app deploy target/smallvaadinapp-1.0-SNAPSHOT.jar --appyaml src/main/appengine/app.yaml

Navigating to the instance will receive Http 500. Logs explorer show NPE.

Versions

• Vaadin / Flow version: 23
• Java version: 17
• OS version: MacOS
• Browser version (if applicable): Firefox
• Application Server (if applicable):
• IDE (if applicable):

[dmitrilc]

Disabling @PWA annotation in the Application.java file will allow the Vaadin app to boot successfully.

//@PWA(name = "Small Vaadin App", shortName = "Small Vaadin App", offlineResources = {})

[taefi]

@dmitrilc thanks for creating this issue. Could you try changing the instance to F2 as mentioned in this blog post: https://foojay.io/today/how-to-deploy-a-vaadin-application-to-google-cloud-app-engine/

[mshabarov]

Closed with provided instructions.

[simasch]

Google App Engine is now by default F2 on Java projects.