Add prometheus metric with version information

[yuvipanda]

• Allows for collection of jupyter server version as a prometheus metric, and filtering of various other metrics based on server version.
• Builds on top of conventions in other servers that expose version (or build) info. For example, kubernetes puts out this metric:

  kubernetes_build_info{build_date="2024-09-09T04:15:23Z", compiler="gc",
  git_commit="fa081458abcdbbc3ddfc3f99546ae5ea45aece17", git_tree_state="clean",
  git_version="v1.29.8-gke.1700", go_version="go1.22.5 X:boringcrypto",
  instance="10.128.0.50:443", job="kubernetes-apiservers", major="1", minor="29",
  platform="linux/amd64"}
  Most of these parameters are not particularly relevant to us, but version is. So this PR only adds version - future labels can be added as needed.

• Fix circular import of jupyter_server.prometheus.metrics when nbclassic shims notebook.prometheus to be the same as jupyter_server.prometheus

[yuvipanda]

Not really sure why it's failing in nbclassic now, although I see nbclassic is doing some fun import schenanigens...

[yuvipanda]

This was a nice debug :)

Due to https://github.com/jupyter/nbclassic/blob/9ae4cb137ea46c9a29cdcf56032dae624f6ff8d8/nbclassic/shim_notebook.py#L72, notebook.prometheus.metrics is actually the same as jupyter_server.prometheus.metrics! So the existing code is actually a circular import:

Traceback (most recent call last):
  File "/Users/yuvipanda/.local/share/virtualenvs/jupyter_server/bin/jupyter-nbclassic", line 5, in <module>
    from nbclassic.notebookapp import main
  File "/Users/yuvipanda/.local/share/virtualenvs/jupyter_server/lib/python3.10/site-packages/nbclassic/__init__.py", line 36, in <module>
    shim_notebook()
  File "/Users/yuvipanda/.local/share/virtualenvs/jupyter_server/lib/python3.10/site-packages/nbclassic/shim_notebook.py", line 80, in shim_notebook
    from jupyter_server import log
  File "/Users/yuvipanda/code/jupyter_server/jupyter_server/log.py", line 15, in <module>
    from .prometheus.log_functions import prometheus_log_method
  File "/Users/yuvipanda/code/jupyter_server/jupyter_server/prometheus/log_functions.py", line 3, in <module>
    from .metrics import HTTP_REQUEST_DURATION_SECONDS  # type:ignore[unused-ignore]
  File "/Users/yuvipanda/code/jupyter_server/jupyter_server/prometheus/metrics.py", line 8, in <module>
    from notebook.prometheus.metrics import (
  File "/Users/yuvipanda/code/jupyter_server/jupyter_server/prometheus/metrics.py", line 8, in <module>
    from notebook.prometheus.metrics import (
ImportError: cannot import name 'HTTP_REQUEST_DURATION_SECONDS' from partially initialized module 'notebook.prometheus.metrics' (most likely due to a circular import) (/Users/yuvipanda/code/jupyter_server/jupyter_server/prometheus/metrics.py)

The ImportError catch was masking this!

[yuvipanda]

I'm not actually sure how to proceed here though, because I'm not fully sure I understand why https://github.com/jupyter/nbclassic/blob/9ae4cb137ea46c9a29cdcf56032dae624f6ff8d8/nbclassic/shim_notebook.py is doing what it's doing. I think it's patching "notebook." things to point to things in jupyter_server, but then it means we can't actually import notebook things in jupyter_server anymore, right? Otherwise you'll end up with circular imports exactly like we are now...

[yuvipanda]

Oooooh, funkier! So notebook.prometheus no longer exists in notebook v7, so we should update the check here.

[yuvipanda]

Quite funny, as we can't actually rely on version info to see if we're on notebook v6, because nbclassic shims version too it looks like :D

[yuvipanda]

I don't see where nbclassic shims notebook._version, but if I print out notebook._version.version_info in the test that was failing, I get (2, 15, 0, '.dev0') so that shimming must be happening somewhere (see https://github.com/jupyter-server/jupyter_server/actions/runs/11567104531/job/32196871585)

[yuvipanda]

All tests pass! That was rewarding.

[yuvipanda]

codespell crampin my styl

[Zsailer]

I love @yuvipanda PRs :)

I'm really swamped this week, but will do my best to give this a solid review tomorrow.

[Zsailer]

This looks good @yuvipanda! Thank you!

[yuvipanda]

ty @Zsailer! This encourages me to add more useful version info metrics, like #1470