Chapter 11. Debugging your application

Procedure

1. In a console, navigate to the directory with your application.

2. Launch your application and specify the debug port using the -Dthorntail.debug.port argument:

   Copy to Clipboard Toggle word wrap

   $ mvn thorntail:run -Dthorntail.debug.port=$PORT_NUMBER

   Here, $PORT_NUMBER is an unused port number of your choice. Remember this number for the remote debugger configuration.

Procedure

1. In a console, navigate to the directory with the uberjar.

2. Execute the uberjar with the following parameters. Ensure that all the parameters are specified before the name of the uberjar on the line.

   Copy to Clipboard Toggle word wrap

   $ java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=$PORT_NUMBER -jar $UBERJAR_FILENAME

   $PORT_NUMBER is an unused port number of your choice. Remember this number for the remote debugger configuration.

   If you want the JVM to pause and wait for remote debugger connection before it starts the application, change suspend to y.

Procedure

1. Using the oc command, list the available deployment configurations:

   Copy to Clipboard Toggle word wrap

   $ oc get dc

2. Set the JAVA_DEBUG environment variable in the deployment configuration of your application to true, which configures the JVM to open the port number 5005 for debugging. For example:

   Copy to Clipboard Toggle word wrap

   $ oc set env dc/MY_APP_NAME JAVA_DEBUG=true

3. Redeploy the application if it is not set to redeploy automatically on configuration change. For example:

   Copy to Clipboard Toggle word wrap

   $ oc rollout latest dc/MY_APP_NAME

4. Configure port forwarding from your local machine to the application pod:

   1. List the currently running pods and find one containing your application:

      Copy to Clipboard Toggle word wrap

      $ oc get pod
      NAME                            READY     STATUS      RESTARTS   AGE
      MY_APP_NAME-3-1xrsp          0/1       Running     0          6s
      ...

   2. Configure port forwarding:

      Copy to Clipboard Toggle word wrap

      $ oc port-forward MY_APP_NAME-3-1xrsp $LOCAL_PORT_NUMBER:5005

      Here, $LOCAL_PORT_NUMBER is an unused port number of your choice on your local machine. Remember this number for the remote debugger configuration.

5. When you are done debugging, unset the JAVA_DEBUG environment variable in your application pod. For example:

   Copy to Clipboard Toggle word wrap

   $ oc set env dc/MY_APP_NAME JAVA_DEBUG-

Procedure

1. Start Red Hat CodeReady Studio.

2. Create a new debug configuration for your application:

   1. Click Run→Debug Configurations.
   2. In the list of configurations, double-click Remote Java application. This creates a new remote debugging configuration.
   3. Enter a suitable name for the configuration in the Name field.
   4. Enter the path to the directory with your application into the Project field. You can use the Browse…​ button for convenience.
   5. Set the Connection Type field to Standard (Socket Attach) if it is not already.
   6. Set the Port field to the port number that your application is listening on for debugging.
   7. Click Apply.

3. Start debugging by clicking the Debug button in the Debug Configurations window.

   To quickly launch your debug configuration after the first time, click Run→Debug History and select the configuration from the list.

Procedure

1. Deploy your application to OpenShift:

   Copy to Clipboard Toggle word wrap

   $ mvn clean oc:deploy -Popenshift

2. View the logs:

   1. Get the name of the pod with your application:

      Copy to Clipboard Toggle word wrap

      $ oc get pods

   2. Start watching the log output:

      Copy to Clipboard Toggle word wrap

      $ oc logs -f pod/MY_APP_NAME-2-aaaaa

      Keep the terminal window displaying the log output open so that you can watch the log output.

3. Interact with your application:

   For example, if you had debug logging in the REST API Level 0 example to log the message variable in the /api/greeting method:

   1. Get the route of your application:

      Copy to Clipboard Toggle word wrap

      $ oc get routes

   2. Make an HTTP request on the /api/greeting endpoint of your application:

      Copy to Clipboard Toggle word wrap

      $ curl $APPLICATION_ROUTE/api/greeting?name=Sarah

4. Return to the window with your pod logs and inspect debug logging messages in the logs.

   Copy to Clipboard Toggle word wrap

   ...
   2018-02-11 11:12:31,158 INFO  [io.openshift.MY_APP_NAME] (default task-18) Hello, Sarah!
   ...

5. To disable debug logging, remove the logging key from the project-defaults.yml file and redeploy the application.