From Fedora Project Wiki


Prevent from building RPM packages providing python3dist(...) = 0

Summary

It sometimes happens that Python packages succeed to build with incorrect version metadata. They generate a wrong provide in format python3dist(...) = 0 and python3.Xdist(...) = 0. While version 0 (or equal versions like 0.0 or 0.0.0) is probably technically valid, in most cases this indicates a packaging error. We propose to prevent this error from happening by explicitly failing the RPM build instead of generating such provides.

Owner

Current status

  • Targeted release: Fedora Linux 38
  • Last updated: 2022-11-11
  • FESCo issue: <will be assigned by the Wrangler>
  • Tracker bug: <will be assigned by the Wrangler>
  • Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

This change is about automatic RPM provides in the following form:

  • python3dist(distname) = 0
  • python3.Xdist(distname) = 0

Where X is the Python minor version (eg. 10, 11...) It does not affect any other provides. More about the provides: https://docs.fedoraproject.org/en-US/packaging-guidelines/Python/#Machine-readable-provides

The provides are automatically generated from upstream metadata and sometimes such information s missing due to packaging error. Setuptools generates sometimes 0 which is bad, we agreed and proposed we will not accept the state

Setuptools sets this to 0.0.0 https://github.com/pypa/setuptools/issues/2329 packaging from git no example when someone wanted to package 0.0.0

An example of the incorrect provides 

$ rpm -qpP python3-ssh-python-0.10.0-5.fc38.x86_64.rpm                                           
python-ssh-python = 0.10.0-5.fc38
python3-ssh-python = 0.10.0-5.fc38
python3-ssh-python(x86-64) = 0.10.0-5.fc38
python3.11-ssh-python = 0.10.0-5.fc38
python3.11dist(ssh-python) = 0
python3dist(ssh-python) = 0


In January 2022 the umbrella Bugzilla ticket was created for Python packages providing this incorrect provide: On Nov 10 2022 there are 22 linked Bugzilla tickets, 13 of which are not closed. New check: 9 packages, in all cases this is wrong The change doesn't affect a big part of the Python ecosystem.

We aim to prevent such situation from happening by increasing the robustness of the python-rpm-generators (namely pythondistdeps.py). The generator will error and fail the build if python3dist(...) = 0 was to be generated. Based on discussion on Fedora-devel there will be no way to opt out from this. Packagers who want to... encouraged to ask upstream to package at least 0.0.1

Feedback

The idea was posted on python-devel mailing list and received a positive feedback. No alternatives to this approach were proposed.

Benefit to Fedora

The correct metadata is essential for the whole package ecosystem. More deterministic behavior of the generators will bring those benefits:

  • The packages will stop lying about the version they provide.
  • The requirements generators (eg. %pyproject_buildrequires) will correctly evaluate the Build- and Runtime Requirements based on the correct Provides.
  • The package maintainers who BuildRequire %{py3dist pkgname} >= 0.2 in their specfiles will always require the correctly evaluated version.

Scope

  • Proposal owners:
  1. implement & test the change in python-rpm-generators (pythondistdeps.py)
  2. ...
  • Other developers:
    • fix the packaging error to generate correct metadata and successful build

TBD how there's no common way to deal with such packages, it's one-by-one issue that originates mostly from packaging errors, ask the change owners if need a way forward


  • Release engineering: not needed for this Change
  • Trademark approval: not needed for this Change
  • Alignment with Objectives: No

Upgrade/compatibility impact

None.


How To Test

TBD take package that provides 0 or prepare a package that has a version 0, build RPM, fail, profit

User Experience

The actual users should notice no difference.

Dependencies

None

Contingency Plan

  • Contingency mechanism: Revert
  • Contingency deadline: Beta freeze
  • Blocks release? No

Documentation

This page is the documentation of this change.

Release Notes

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