Ceph

pip 25.3 requires PEP 517 pyproject.toml files instead of just using current setup.py in src/pybind/* .
pip release notes about it: https://pip.pypa.io/en/latest/news/
PEP 517: https://peps.python.org/pep-0517/
PEP 518: https://peps.python.org/pep-0518/

This is a problem because readthedocs now uses pip 25.3 by default which causes the src/pybind/* job to fail, for example from https://app.readthedocs.org/projects/ceph/builds/30075615/ :

python -m pip install --exists-action=w --no-cache-dir -r admin/doc-pybind.txt  
Processing ./src/pybind/rados
  Installing build dependencies: started
  Installing build dependencies: finished with status 'done'
  Getting requirements to build wheel: started
  Getting requirements to build wheel: finished with status 'error'
  error: subprocess-exited-with-error

  × Getting requirements to build wheel did not run successfully.
  │ exit code: 1
  ╰─> [2 lines of output]
      ERROR: Cannot find Cythonized file rados.c
      WARNING: Cython is not installed.
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
ERROR: Failed to build 'file:///home/docs/checkouts/readthedocs.org/user_builds/ceph/checkouts/66058/src/pybind/rados' when getting requirements to build wheel

I am currently looking at implementing a workaround for RTD builds to use pip 25.2. A quick and dirty change confirms the RTD build succeeds with pip 25.2.