PBR enhancements to support pip

pip, the Python package installation tool is looking for something very much like pbr. pbr itself will benefit from the generalisations pip is looking for.

Problem description

There are a few places where pbr today doesn’t meet pips needs.

  1. pbr requires pbr be easy_installable or pre-installed for both from-git and from-tarball installations. This is sufficiently fragile that pip wishes to avoid it from from-tarball situations. pbr has had that requested of it already by OpenStack users.
  2. pbr has no way to turn off requirements.txt reflection. This is already planned as part of converging on upstream practices.
  3. Needs to be able to generate dynamic entry points based on the Python environment being installed into. e.g. foo, foo2, foo2.7, when installing into Python 2.7, whether globally or a venv.

Proposed change

embed pbr in sdists

Via an opt-in option we can embed pbr in the root directory of the sdist. When run from an sdist, the local directory is first in the Python path and this will cause the embedded copy of pbr to be found and loaded. The embedding process will copy a statically defined subset of the pbr source code (and we may wish to refactor things a little to make this more manageable). pbr’s non-test code is 128K today uncompressed, 30K compressed - which is tolerable. Embedding all of pbr permits tests, doc builds and so on to all work from an sdist.

opt-out of requirements.txt reflection

We’ll add an option, skip_requirements_files to disable requirements file reflection. When set requirements will be managed via setup.cfg or setup.py exclusively. This is in line with our eventual deprecation of those files.

entry point merging

Rather than introducing a template language that wouldn’t be supported by wheels, we’ll allow setup() to pass in entry points and merge them. That will prevent this being an attractive-nuisance within OpenStack while still permitting pip to perform its current workarounds for the lack of entry point templating in the wider set of tooling.

Alternatives

  1. Say ‘no, thats not pbr’ to pip. Unnecessary. Growing the ecosystem is part of OpenStack’s mission.

Implementation

Assignee(s)

Primary assignee/contact:
Robert Collins - lifeless

Work Items

  1. Embedding pbr in sdists.
  2. Opting out of requirements reflection.

Dependencies

None

History

Revisions
Release Name Description
Mitaka Introduced

Note

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