Python Build Reasonableness
PBR is a library that injects some useful and sensible default behaviors into your setuptools run. It started off life as the chunks of code that were copied between all of the OpenStack projects. Around the time that OpenStack hit 18 different projects each with at least 3 active branches, it seems like a good time to make that code into a proper re-usable library.
PBR is only mildly configurable. The basic idea is that there’s a decent way to run things and if you do, you should reap the rewards, because then it’s simple and repeatable. If you want to do things differently, cool! But you’ve already got the power of python at your fingertips, so you don’t really need PBR.
PBR builds on top of d2to1 to provide for declarative configuration. It then filters the setup.cfg data through a setup hook to fill in default values and provide more sensible behaviors.
What It Does
PBR can and does do a bunch of things for you:
- Version: Manage version number bad on git revisions and tags
- AUTHORS: Generate AUTHORS file from git log
- ChangeLog: Generate ChangeLog from git log
- Sphinx Autodoc: Generate autodoc stub files for your whole module
- Requirements: Store your dependencies in a pip requirements file
- long_description: Use your README file as a long_description
- Smart find_packages: Smartly find packages under your root package
Version strings will be inferred from git. If a given revision is tagged, that’s the version. If it’s not, and you don’t provide a version, the version will be very similar to git describe. If you do, then we’ll assume that’s the version you are working towards, and will generate alpha version strings based on commits since last tag and the current git sha.
Sphinx can produce auto documentation indexes based on signatures and docstrings of your project- but you have to give it index files to tell it to autodoc each module. That’s kind of repetitive and boring. PBR will scan your project, find all of your modules, and generate all of the stub files for you.
Sphinx documentation setups are altered to generate man pages by default. They also have several pieces of information that are known to setup.py injected into the sphinx config.
You may not have noticed, but there are differences in how pip requirements.txt files work and how distutils wants to be told about requirements. The pip way is nicer, because it sure does make it easier to popuplate a virtualenv for testing, or to just install everything you need. Duplicating the information, though, is super lame. So PBR will let you keep requirements.txt format files around describing the requirements for your project, will parse them and split them up approprirately, and inject them into the install_requires and/or tests_require and/or dependency_links arguments to setup. Voila!
There is no need to maintain two long descriptions- and your README file is probably a good long_description. So we’ll just inject the contents of your README.rst, README.txt or README file into your empty long_description. Yay for you.
pbr requires a distribution to use distribute. Your distribution must include a distutils2-like setup.cfg file, and a minimal setup.py script.
A simple sample can be found in pbr s own setup.cfg (it uses its own machinery to install itself):
[metadata] name = pbr author = OpenStack Foundation author-email = email@example.com summary = OpenStack's setup automation in a reuable form description-file = README license = Apache-2 classifier = Development Status :: 4 - Beta Environment :: Console Environment :: OpenStack Intended Audience :: Developers Intended Audience :: Information Technology License :: OSI Approved :: Apache Software License Operating System :: OS Independent Programming Language :: Python keywords = setup distutils [files] packages = oslo [hooks] setup-hooks = pbr.hooks.setup_hook
The minimal setup.py should look something like this:
#!/usr/bin/env python from setuptools import setup setup( setup_requires=['d2to1', 'pbr'], d2to1=True, )
Note that it’s important to specify d2to1=True or else the pbr functionality will not be enabled.
It should also work fine if additional arguments are passed to setup(), but it should be noted that they will be clobbered by any options in the setup.cfg file.
The testing system is based on a combination of tox and testr. The canonical approach to running tests is to simply run the command tox. This will create virtual environments, populate them with depenedencies and run all of the tests that OpenStack CI systems run. Behind the scenes, tox is running testr run –parallel, but is set up such that you can supply any additional testr arguments that are needed to tox. For example, you can run: tox – –analyze-isolation to cause tox to tell testr to add –analyze-isolation to its argument list.
It is also possible to run the tests inside of a virtual environment you have created, or it is possible that you have all of the dependencies installed locally already. If you’d like to go this route, the requirements are listed in requirements.txt and the requirements for testing are in test-requirements.txt. Installing them via pip, for instance, is simply:
pip install -r requirements.txt -r test-requirements.txt
In you go this route, you can interact with the testr command directly. Running testr run will run the entire test suite. testr run –parallel will run it in parallel (this is the default incantation tox uses.) More information about testr can be found at: http://wiki.openstack.org/testr