From Fedora Project Wiki
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== Detailed Description ==
 
== Detailed Description ==
  
If during the building of a Python package RPM encounters <code>.egg-info</code>, <code>.egg-link</code> or <code>.dist-info</code> files (provided in Python Wheels and Eggs), it will read the standardized name of the software (i.e. dist name, name on PyPI) in the canonical format and create a virtual Provides tag with the value <code>pythonX.Ydist(CANONICAL_NAME)</code>, where <code>X.Y</code> is the used Python version.
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If during the building of a Python package RPM encounters <code>.egg-info, .egg-link</code> or <code>.dist-info</code> files (provided in Python Wheels and Eggs), it will read the standardized name of the software (i.e. dist name, name on PyPI) in the canonical format and create a virtual Provides tag with the value <code>pythonX.Ydist(CANONICAL_NAME)</code>, where <code>X.Y</code> is the used Python version.
 
Note that the canonical format can differ slightly from the name displayed, for example, on PyPI.<ref name="canonical">The canonical name is obtained by switching the standardized name to lower case and converting all non-alphanumeric runs to single “-” characters. Example: “The $$$ Tree” becomes “the-tree”.</ref>
 
Note that the canonical format can differ slightly from the name displayed, for example, on PyPI.<ref name="canonical">The canonical name is obtained by switching the standardized name to lower case and converting all non-alphanumeric runs to single “-” characters. Example: “The $$$ Tree” becomes “the-tree”.</ref>
  

Revision as of 11:35, 28 June 2016

Automatic Provides for Python RPM Packages

Summary

Upon building Python packages containing packaging metadata, RPM will automatically detect the standardized name of the software (i.e. dist name, name on PyPI) in the canonical format[1] and create a virtual Provides tag with the value pythonX.Ydist(CANONICAL_NAME), where X.Y is the used Python version. RPM may also detect dependencies of the software from the metadata and automatically require them using the same syntax.

Owner

Current status

  • Targeted release: Fedora 25
  • Last updated: 2016-06-28
  • Tracker bug: <will be assigned by the Wrangler>

Detailed Description

If during the building of a Python package RPM encounters .egg-info, .egg-link or .dist-info files (provided in Python Wheels and Eggs), it will read the standardized name of the software (i.e. dist name, name on PyPI) in the canonical format and create a virtual Provides tag with the value pythonX.Ydist(CANONICAL_NAME), where X.Y is the used Python version. Note that the canonical format can differ slightly from the name displayed, for example, on PyPI.[1]

RPM will also detect dependencies of the software from the aforementioned metadata files and automatically require them using the format pythonX.Ydist(). However, because these files don't always contain the full list of requirements (which are either in setup.py or requirements.txt), the dependency generator will not be conclusive.

All Python packages will need to be rebuilt so that the virtual Provides tags are generated and can be used by users, scripts and the requires generator.

Benefit to Fedora

Packaging Python software will become easier, and (semi-)automatic tools for creating Python packages like pyp2rpm [1] will be significantly more effective due to this change.

Scope

  • Proposal owners: Prepare a draft for the Fedora Packaging Guidelines for Python
  • Maintainers of the RPM package: Backport the functionality from upsteram to Fedora. — Already done thanks to Florian Festi [2]
  • Release engineering: Targeted rebuild of Python packages. Ticket [3].
    • List of deliverables: All Fedora deliverables will be affected, but only in a very minor way that in no way jeopardizes their delivery.
  • Policies and guidelines: Fedora Packaging Guidelines for Python need to be updated after the implementation so users know how to take advantage of the change.
  • Trademark approval: Not needed for this Change

Upgrade/compatibility impact

No issues expected of any kind.

How To Test

0. Pick any Python software that is both packaged for Fedora and present on PyPI.

1. dnf install pythonX.Ydist(CANONICAL_NAME) where X.Y is one of the Python versions for which the software is packaged in Fedora (for Fedora 24 it is most likely 3.5 and/or 2.7) and inside the parentheses is the standardized name of the software (dist name, name on PyPI) in its canonical format.[1]

Expected results: The correct package is installed.

User Experience

Users will be able to use dnf to install software from PyPI without knowing under what name the software is packaged in Fedora. In the future, tools that mimic pip installation using dnf may be evolved.

Dependencies

None

Contingency Plan

  • Contingency mechanism: Do not update the Fedora Packaging Guidelines
  • Contingency deadline: Alpha Freeze
  • Blocks release? No
  • Blocks product? None

Documentation

  • Information about the backport of this feature on Bugzilla. [4]
  • Descriptive commit message on RPM upstream: [5]
  • Python-devel mailing list discussion: [6]

Release Notes

Notes

  1. 1.0 1.1 1.2 The canonical name is obtained by switching the standardized name to lower case and converting all non-alphanumeric runs to single “-” characters. Example: “The $$$ Tree” becomes “the-tree”.