Sometimes, debugging an application locally is insufficient to pinpoint the underlying issue. Additionally, there are times when the infrastructure limitations do not allow one to debug an application. In such scenarios, remote debugging is a reasonable approach. However, that requires some preparations. In this article, we cover how to remote debug a Spring Boot application deployed in Kubernetes.
To remote debug a Spring Boot application deployed in Kubernetes, we have to take the following steps:
- Enable JVM remote debug and expose a debug port
- Expose the debug port through Kubernetes deployment
- Port forward the debug port to the local
Enable JVM remote debug and expose a debug port
When running the application with the
java command, we need to attach JWDP (Java Debug Wire Protocol) to the JVM process as follows:
$ java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005 \
That exposes the port 5005 as a debug port that we can attach to a remote debugger (e.g., IntelliJ debugger).
For Kubernetes deployment, you should apply the changes to your
Dockerfile and build the image again.
Expose the debug port through Kubernetes deployment
The next step is to expose the debug port (
5005 in this case) in Kubernetes and make it accessible through the cluster first and then outside via port forwarding.
For that, we need to edit the Kubernetes deployment file. For Helm, you should edit the
values.yml file in your Helm chart. Nonetheless, go through your deployment. Most probably your application is already exposing a port. Just find it and add a line after that. For example,
- containerPort: 8080
- containerPort: 5005
Of course, if you don’t want to go through the process of publishing a Helm chart, you can edit the deployment via the
$ kubectl -n [namespace] edit deployment [deployment_name]
Port forward the debug port
The last step is to port forward the debug port,
5005, to local. That can be done via
kubectl as follows:
$ kubectl -n [namespace] port-forward [pod_name] 5005:5005
Lastly, we must attach the debugger to the remote JVM on port 5005. For that purpose, we use IntelliJ.
We need to create a remote debug configuration like below,
In this article, we covered how to remote debug a Spring Boot application in Kubernetes. Although the process is not as simple as local debugging, it requires only a few small steps to connect to a Spring Boot application running in a Kubernetes pod to debug.