Debugging with the python plugin behaves strangely

[amisevsk]

Describe the bug

There are numerous issues with trying to debug in the python-simple devfile.

• It's only possible to use code completion to generate debug configs if launch.json does not already exist
• Debug > Add configuration does not work.
• Many of the suggested generate options seem to do nothing when clicked.
• Once created, I can't get any of the debug configurations to work.

Che version

Server: eclipse/che-server:nightly-centos
Python Plugin: ms-python/python/latest
Workspace: quay.io/eclipse/che-python-3.6:nightly, eclipse/che-theia:7.0.0-next, eclipse/che-remote-plugin-python-3.7.3:7.0.0-next

Steps to reproduce

1. Start python-simple devfile

2. Open hello-world.py and set breakpoint on print statment

3. Navigate Debug > Open Configurations

   • Instead of opening debug configurations, Che shows a dropdown with options: (Only "Python File" does anything)
     

4. Create "Python File" debug config and try to launch

   • Timeout waiting for debugger connection

5. Attempt to add different debug configuration

   • Completion just shows "Python" entry that does nothing:
     

   • It's no longer possible to add debug configurations via completion until launch.json is deleted

Expected behavior

Something simpler than the above

Runtime

• kubernetes (include output of kubectl version)
• Openshift (include output of oc version)
• minikube (include output of minikube version and kubectl version)
• minishift (include output of minishift version and oc version)
• docker-desktop + K8S (include output of docker version and kubectl version)
• other: (please specify)

Installation method

• chectl
• che-operator
• minishift-addon
• I don't know

[amisevsk]

Potentially related: #13816, although this issue applies to a simple "hello world" application.

[tsmaeder]

Suspicion from @tolusha is that some VS Code API is missing in Theia that is used here.

[tolusha]

Investigation shows Theia seems to misbehave. Theia collects configurations snippets and shows them during completion in launch.json. But python plugin doesn't have any configurations snippets. The only way to request configurations is to invoke provideDebugConfiguations method when use select Python entry. But it never happens.

There is particular case when provideDebugConfiguations is invoked [1]. It happens when there is no launch.json and any python file is opened in the editor.

[1] https://github.com/theia-ide/theia/blob/master/packages/debug/src/browser/debug-configuration-manager.ts#L274

[tolusha]