Added error propagation to gateway_request function

[broden-wanner]

Summary

Feature for #1231. With this change, error messages from Enterprise Gateway will be propagated through Jupyter Server to the frontend. Looking through the Enterprise Gateway code, it seems that the JSON payload returned should only contain a reason field or a message field (or both possibly). See the code for the log_and_raise method of the processproxy here where the reason field is populated, and also see the swagger spec that lists only reason and message as possible properties. However, in my own testing, I've noticed the message and reason fields might not be in the body of the error (it's usually only one of them), so I've added logic to account for the fields missing or non-JSON payloads being returned. See relevant discussion on the Jupyter community forum here.

Screenshots

The following screenshots show the before and after error messages displayed on Jupyter lab when kernel creation times out.

Before

Error message in text: HTTP 500: Internal Server Error (Error attempting to connect to Gateway server url 'https://mygatewayurl'. Ensure gateway url is valid and the Gateway instance is running.)

After

Error message: HTTP 500: Internal Server Error (Error from Gateway: [Internal Server Error] KernelID: '094f5160-163a-4025-94cf-5d8922808dd3' launch timeout due to: Waited too long (40.0s) to get connection file. Ensure gateway url is valid and the Gateway instance is running.)

Tests

No test cases were modified, and it doesn't seem that any have failed. I noticed that the gateway_request function is mocked in testing and doesn't seem to be directly used in the tests. Let me know if you'd like any tests to be added for this error propagation.

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[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.13 ⚠️

Comparison is base (4513527) 80.47% compared to head (e11e27e) 80.35%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1233      +/-   ##
==========================================
- Coverage   80.47%   80.35%   -0.13%     
==========================================
  Files          68       68              
  Lines        8252     8261       +9     
  Branches     1599     1600       +1     
==========================================
- Hits         6641     6638       -3     
- Misses       1189     1200      +11     
- Partials      422      423       +1     

Impacted Files	Coverage Δ
jupyter_server/gateway/gateway_client.py	76.41% <0.00%> (-2.11%)	⬇️
...ter_server/services/kernels/connection/channels.py	61.72% <0.00%> (-0.45%)	⬇️
jupyter_server/serverapp.py	80.63% <0.00%> (-0.09%)	⬇️

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[kevin-bates]

These changes look good - thank you @broden-wanner!

[lresende]

Can we also backport this to 1.x branch?

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Congrats on your first merged pull request in this project! 🎉

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[blink1073]

@meeseeksdev please backport to 1.x

[kevin-bates]

Hi @blink1073 - Is there a chance we could get a 1.x release that contains this change?

[blink1073]

Done: https://github.com/jupyter-server/jupyter_server/releases/tag/v1.24.0

[kevin-bates]

Thank you @blink1073!

[broden-wanner]

Thank you @kevin-bates and @blink1073! Much appreciated!