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javagoogle-app-enginejettydev-appserver

Debug application on Jetty on Google App Engine (localhost)

I am trying to run a localhost Dev App Engine running my application via Jetty. As seen the Dev App Engine starts:

[INFO] Sep 20, 2016 9:43:39 AM com.google.appengine.tools.development.AbstractModule startup
[INFO] INFO: Module instance default is running at http://localhost:8080/
[INFO] Sep 20, 2016 9:43:39 AM com.google.appengine.tools.development.AbstractModule startup
[INFO] INFO: The admin console is running at http://localhost:8080/_ah/admin
[INFO] Sep 20, 2016 9:43:39 AM com.google.appengine.tools.development.DevAppServerImpl doStart
[INFO] INFO: Dev App Server is now running

I try and access the admin page at http://localhost:8080/_ah/admin:

HTTP ERROR: 404

Problem accessing /_ah/admin. Reason:

    NOT_FOUND
Powered by Jetty://

I suspect my application has crashed on Jetty. Hows does one debug this?

I don't know what information is needed to you guys to help. Tell me!

Solution

    1. You have to update appengine-maven-plugin with the remote debugging jvm argument as below.

      <configuration> <jvmFlags> <jvmFlag>-Xdebug</jvmFlag> <jvmFlag>-agentlib:jdwp=transport=dt_socket,address=5005,server=y,suspend=n</jvmFlag> </jvmFlags> </configuration>

    2. Then run your dev server using mvn appengine:devserver command

    3. Point your IDE to remote debugging port(5005)