default runtime images can not be removed

Currently when you attempt to remove one of the default runtime images, say Pandas 1.1.1, you get the error:

Removal of instance 'pandas' from the runtime-images schemaspace is not permitted!

The JupyterLab logs show:

[E 2022-02-14 07:18:24.837 ElyraApp] Removal of instance 'pandas' from the runtime-images schemaspace is not permitted!  Resource conflict at '/opt/conda/share/jupyter/metadata/runtime-images/pandas.json'                                                                                                                                                  
[W 2022-02-14 07:18:24.837 ServerApp] 403 DELETE /notebook/kf-development/elyra-3-6-0/elyra/metadata/runtime-images/pandas?1644823104409 (127.0.0.6): Removal of instance 'pandas' from the runtime-images schemaspace is not permitted!                                                                                                                      
[W 2022-02-14 07:18:24.837 ServerApp] 403 DELETE /notebook/kf-development/elyra-3-6-0/elyra/metadata/runtime-images/pandas?1644823104409 (127.0.0.6) 2.38ms referer=https://xxxxxxx/lab/workspaces/auto-b 

[ptitzler]

We could also document how users could export/import the images they wish to retain. (Of course, we’d need the necessary import functionality in place, but I’m assuming this (removal of system-owned RTIs) is something slated for 4.0.)

Yep. Metadata import should be available no later than 3.8. We could also add the current files to the examples repository or document the corresponding CLI commands, which are straightforward for RTIs.

[ptitzler]

Perhaps we should reevaluate whether this system-owned RTI metadata is even necessary. If I recall correctly, system RTIs were provided to provide a smother up-and-running experience. My thoughts:

• For container based deployments, pre-seeded container images can be provided through other means:
  • publish -slim image (e.g. elyra-slim), which don’t have any RTIs pre-defined. Users can extend this image FROM ..../elyra-slim and add elyra-metadata install runtime-images ..., specifying their own images.
  • publish elyra image, which extends above image using a small set of images (a subset of what we include today)
• Pre-seeded RTI metadata is useful for getting started scenarios, but in many cases it’d be just one additional step to add it to an Elyra instance that doesn’t have it defined. (Additional tutorial artifacts can be provided to create the metadata on as as needed basis. For example, https://github.com/elyra-ai/examples/tree/master/pipelines/dax_noaa_weather_data only requires one RTI instance to be fully functional.)
• As is, system-owned RTIs don’t really solve many problems: (1) users can overwrite them and (2) users can add/use their own, hence the mechanism does nor enforce any restrictions that an admin might want to impose.