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pbr and semver

aka Python Build Reasonableness and Semantic Versioning

Robert Collins
rbtcollins@hp.com
@rbtcollins (Twitter)

Setuptools

Note: "Anthony baxter" - Very clever code written by very clever people

OpenStack

  • Dozens of projects
  • Identical infrastructure code
  • Maintenance nightmare

Note: Lots of simple code in a complex environment...

Refactor

  • New project
  • Setuptools plugin
  • Used by all OpenStack projects

Note: What do we do to fix DRY problems? We add an abstraction. What problem cannot be solved by adding abstractions?

PBR

Consistent setuptools integration glue for all OpenStack projects.

Depends on git and a recent pip for installation support.

Getting started with PBR

setup.py

#!/usr/bin/env python

import setuptools
setuptools.setup(
    setup_requires=['pbr'],
    pbr=True)

setup.cfg

[metadata]
name = os-apply-config
author = OpenStack
author-email = openstack-dev@lists.openstack.org
summary = Config files from cloud metadata
description-file = 
        README.rst
home-page = http://git.openstack.org/cgit/openstack/os-apply-config
classifier = 
        Development Status :: 4 - Beta
....
        Programming Language :: Python

[files]
packages = 
        os_apply_config

[entry_points]
console_scripts =
        os-apply-config = os_apply_config.apply_config:main

PBR Features

Testing

  • entrypoint integrated
python setup.py test

Note: testr integration, driven through tox

git integration

Hard requirement but....

  • automatically picks up all versioned files
  • scans history for changelog and authors file contents

PyPI integration

Generates a rich summary from README.rst + changelog

Documentation

Sphinx API glue, and Sphinx manpage output.

PIP

Pulls requirements from requirements*.txt

Note: This is another DRY situation

Versioning

Generates pre-release version numbers for you from tags and or config settings

Note: blank.. lets talk about consistency a little. You know, that thing where you do the same thing.. openstack and API servers (2012.1) vs clients (1.2.3).

Semantic versioning

semver is a simple and clear set of rules for versioning software to clearly indicate compatibility interactions. Note: Which we adopted. And then realised it didn't quite work. So we changed it :).

openstack-semver

"This is a fork of Semantic Versioning 2.0. The specific changes have to do with the format of pre-release and build labels, specifically to make them not confusing when co-existing with Linux Distribution packaging. Inspiration for the format of the pre-release and build labels came from Python's PEP440."

Issues

dev builds

  • 1.3.2 tagged
  • 5 local commits
  • 1.3.2.5.g$sha

Note: 1.3.2 tagged, 1.3.2.N.g$sha - counts as a full release

pbr-semver

Developers don't know the semver rules we've settled on:

  • tag 1.3.2.a2
  • should be 1.3.2.0a2 Note: 1.3.2.a2 -> 1.3.2.0a2

CD

1.3.2.0a1 cannot be sorted vs 1.3.2.dev5 Note: Folk pulling trunk want monotonic versions but dev versions have no precedence vs alpha/beta/rc in semver

Binary Packaging

Turns out everyone reinvents the same integration and version translation glue... differently. Note: mention Debian vs Ubuntu, Redhat vs third parties... touch on sort-before

Sort-before

1.3.2.0a1 sorts before 1.3.2 - versions are special. dpkg has ~ rpm has nothing

pbr-semver

  • new
  • shiny
  • magic

Strict pbr-semver mode

Enforce pbr-semver compatible version numbers

Epic fail on existing versions

Have to parse every version we ever accepted:

1.2.1a1
1.2.3.4.g123
1.2.b1
1.2b1
2.1.0.rc1

History scanning

Scan git history for pseudo headers and calculate new release versions

Before: pbr-0.10.1.dev5.gaada1d1

Look for and process sem-ver pseudo headers in git

At the moment careful changelog review is needed by humands to
determine the next version number. Semantic versioning means that all
we need to know to get a reasonable default next version (and a lower
bound on the next version) is a record of bugfix/deprecation/feature
work and api-breaking commits. In this patch we start scanning for
such headers from the git history to remove this burden from
developers/project release managers. Higher versions can of course
be used either via pre-versioning or by tagging the desired version.

implements: blueprint pbr-semver
sem-ver: feature  <--------------------------------------------------
Change-Id: Id5e8cd723d5186d1bd8c01599eae8933e6f7ea6d

After: pbr-0.11.0.dev5.gaada1d1

sem-ver: feature
sem-ver: api-break
sem-ver: deprecation
sem-ver: bugfix
sem-ver: bugfix, api-break

Note: no line == sem-ver:bugfix

(planned) Doing releases

W#rap git tag to make releases trivial

python setup.py tag-release

(planned) Doing binary (distro) builds

Provide helpers to generate dpkg and RPM versions from a semver version

setup.py deb-version
1.2.0~0b1
setup.py rpm-version
1.1.9999.1

Exporting versions as version_info tuples

import pbr.version
...
_version = pbr.version.VersionInfo('MYPACKAGE').semantic_version()
__version__ = _version.version_tuple()
version = _version.release_string()
...
>>> MYPACKAGE.version
'0.0.4.dev1.gca18f39'
>>> MYPACKAGE.__version__
(0, 0, 4, 'alpha', 0)

(planned) Allow disabling pre-release versions for CD folk

python setup.py sdist
...
1.3.2.0a1
python setup.py sdist --no-rc
1.3.2.dev34.g$sha

Questions?