How to debug a component
This page explains how to debug a component using odo and the according actions in IntelliJ.
The Debug action is implemented since version 0.2.0.
The Debug action is actually limited to Java and NodeJS component types.
Debugging Java components is available in IntelliJ Community and Ultimate.
However, to debug nodejs components, the JavaScript Debugger plugin is required and is only available to licensed versions of IntelliJ (Ultimate, WebStorm).
See https://www.jetbrains.com/idea/features/editions_comparison_matrix.html
To debug a component, it must be already pushed in the cluster. The debug action is not visible when the component is not pushed or has no context.
When the component is pushed, the Debug action is visible only on Java and NodeJS component types.
When the Debug action is selected, an odo debug command is run in a terminal, and a Run Configuration is launched to connect the according debugger with odo, using a random available port.
The odo command line displays a message like Started port forwarding at ports - 41655:5858 where 41655 is the local port used to connect the debugger to odo and 5858 is the component port opened in the pod.
For more information about using a different component port, see https://github.com/openshift/odo/blob/master/docs/proposals/odo-debug.md
Depending on the component type, the debugger can be either the Java remote debugger or the JavaScript remote debugger.
When a breakpoint set in the source code of the component is hit, the debugger will act as usual:
You can navigate into the variables, do step by step debugging, ...
You can stop the debugger by using the usual stop buttons or shortcut in IntelliJ.
Please note that the component is still running on the cluster and odo is also still running on the terminal.
Below are animations that shows how a debug is performed from the OpenShift view, when a component is already pushed to the cluster. Click on the image to see the video.
Java debug:
Node.js debug:
Yes, you can push any modifications on the cluster while the debugger is running. The local debugger will stop and you need to run the debug configuration again to reconnect to the component. This can take time as the push may rebuild the component.
Yes, if each run configuration uses different local ports, you can debug as many components as you want. If the debugger is trying to connect to port not available, a message will be displayed. Also, if you try to run the same configuration twice, a message will be displayed.
Yes, the run configuration settings are used to determine the local port when the Debug action is selected.
Also, you can delete the run configuration, a new one will be automatically created when needed.
First stop the debugger, then select the Terminal tab. Locate the odo debug terminal and right click on it, then select Close Session.
Select the Terminal tab. Locate the odo debug terminal and take a look at the messages.