Changes/Prevent-Providing-python3dist(pkg)=0

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

Summary

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

Owner

• Name: Miro Hrončok, Karolina Surma
• Email: mhroncok@redhat.com, ksurma@redhat.com

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:

• python3(.x)dist(distname) = 0

It does not affect any other provides. More about the provides: https://docs.fedoraproject.org/en-US/packaging-guidelines/Python/#Machine-readable-provides

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: https://bugzilla.redhat.com/showdependencytree.cgi?id=python3dist0 On Nov 10 2022 there are 22 linked Bugzilla tickets, 13 of which are not closed. 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: https://src.fedoraproject.org/rpms/python-rpm-generators/blob/rawhide/f/pythondistdeps.py). The generator will error and fail the build if python3dist(pkgname) = 0 was to be generated.

Feedback

The idea was posted on python-devel mailing list and received a positive feedback. No alternatives to this approach were proposed: https://lists.fedoraproject.org/archives/list/python-devel@lists.fedoraproject.org/thread/K35JCFVJLETVUOICQM634OSYBYQ3Q2WQ/

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} 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 prevent from generating such metadata

TBD how

• Release engineering: not needed for this Change

• Policies and guidelines: not needed for this Change

• Trademark approval: not needed for this Change

• Alignment with Objectives: No

Upgrade/compatibility impact

None.

How To Test

TBD

User Experience

The actual users should notice no difference.

Dependencies

TBD

Contingency Plan

• Contingency mechanism: TBD
• Contingency deadline: TBD
• Blocks release? No

Documentation

N/A (not a System Wide Change)