Debugging Camel K Integrations
Sometimes integrations can fail or behave unexpectedly for unknown reasons and a developer needs to investigate the cause of such behavior. Attaching a Java debugger to an integration is a common way to start the investigation.
Even if Camel K integrations run on a Kubernetes cluster, it’s very easy to attach a Java debugger to the remote integration using the CLI.
If you’re a VS Code user, you can watch this video.
Find below a more generic explanation using IntelliJ.
Suppose you just launched an integration using the following command:
kamel run examples/Sample.java
An integration named
sample should be running in the cluster. You can use the
kamel debug command to put it in "debug mode".
kamel debug sample
A possible output that you may find is the following:
$ kamel debug sample Enabling debug mode on integration "sample"...  Monitoring pod sample-8455c8b985-5cxvc  exec java -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005 -cp ./resources:[..omitted..] io.quarkus.runner.GeneratedMain  Listening for transport dt_socket at address: 5005 Forwarding from 127.0.0.1:5005 -> 5005 Forwarding from [::1]:5005 -> 5005
As you can see in the logs, the CLI has configured the integration in debug mode (see option
-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005) and started forwarding the local port 5005 on the workstation machine (local port can be changed using the
--port option) to the container port 5005, where the JVM is waiting for a debugger.
The JVM is suspended and waits for a debugger to attach by default: this behavior can be turned off using the
Last thing to do is, with your IDE opened on the integration file (if using Java, Groovy or Kotlin), the Apache Camel project or the Camel K Runtime project, to start a remote debugger on
The following picture shows the configuration of a remote debugger in IntelliJ Idea.
Once you configure a debugger, you can add breakpoints to various part of the code, then connect the debugger to trigger the JVM startup.
When the debugging session is finished, hitting ctrl+c on the terminal where the kamel CLI is running will restore the integration to its original status.