Repo provides an example of remote debugging a Python Application(Flask) on Kubernetes/OpenShift with VSCode.

• Repo uses python debugpy as debugger.
• Application used for example is testFlask Application
• Example uses a Dockerfile to build application image.
• Dockerfile entrypoint points to bash script that helps determine if remote debugging is needed via the use of environment variables.
• if Debugging is needed bash script will run python flask entrypoint file which imports debug intializer from another file if required.

• debugpy
• Debugging Approach Example
• Kubernetes Debugging with VSCode

• OpenShift Cluster - Version>=4.9
• oc client >= 4.9
• oc client must be logged in with user with sufficent privileges to run below commands.

• Source Environment Variables

  eval "$(curl https://raw.githubusercontent.com/MoOyeg/testFlask/master/sample_env)"

• Create necessary projects
  oc new-project $NAMESPACE_DEV
  oc new-project $NAMESPACE_PROD

• Create a new application on openshift, using the oc new-app command.We will specificy environment variables we pre-configured in our entrypoint bash script to enable debugging for our application

  oc new-app https://github.com/MoOyeg/testFlask.git --name=$APP_NAME -l app=testflask --env=REMOTE_DEBUG="true" --env=DEBUG_PORT=5679 -n $NAMESPACE_DEV --strategy=docker

• If the previous command gives this error - error: unable to locate any images in image streams, local docker images with name "image-registry.openshift-image-registry.svc:5000/openshift/ubi8"

  oc tag --source=docker registry.redhat.io/ubi8/ubi:latest ubi8:latest -n openshift

• Expose the service to the outside world with an openshift route

  oc expose svc/$APP_NAME --port 8080 -n $NAMESPACE_DEV

• If app build above is successful our application pod should start in debug mode. We can confirm by looking at application logs.

  oc logs deployment/$APP_NAME -n $NAMESPACE_DEV

  

• With our application debugger listening we need to port-forward from our debug service to allow vscode connect.

  oc port-forward service/$APP_NAME -n $NAMESPACE_DEV --address 0.0.0.0  5679:5679

  

• With our debugger accessible we need to configure our vscode instance to connect to the debugging session. Port-Forward session has to continously run for duration of debugging

  • Clone the original source code

       git clone https://github.com/MoOyeg/testFlask.git

  • Open folder in VSCode

  • Set your vscode setting.json to point to our created instance above and use the remote debug configuration. I have provided a sample settings.json with a remote debugger attach and local development example under .vscode folder.

    

  • Start debug session in vscode, we should see log in our application show a debug connection has been made.

    oc logs deployment/$APP_NAME -n $NAMESPACE_DEV

    

• Calling our route URL for the application should trigger our breakpoints.

   curl $(oc get route/$APP_NAME -n $NAMESPACE_DEV -o jsonpath='{.spec.host}')