pbr - Python Build Reasonableness

A library for managing setuptools packaging needs in a consistent manner.

pbr reads and then filters the setup.cfg data through a setup hook to fill in default values and provide more sensible behaviors, and then feeds the results in as the arguments to a call to setup.py - so the heavy lifting of handling python packaging needs is still being done by setuptools.

Note that we don’t support the easy_install aspects of setuptools: while we depend on setup_requires, for any install_requires we recommend that they be installed prior to running setup.py install - either by hand, or by using an install tool such as pip.

What It Does

PBR can and does do a bunch of things for you:

  • Version: Manage version number based on git revisions and tags
  • AUTHORS: Generate AUTHORS file from git log
  • ChangeLog: Generate ChangeLog from git log
  • Manifest: Generate a sensible manifest from git files and some standard files
  • 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

Versions can be managed two ways - postversioning and preversioning. Postversioning is the default, and preversioning is enabled by setting version in the setup.cfg metadata section. In both cases version strings are inferred from git.

If the currently checked out revision is tagged, that tag is used as the version.

If the currently checked out revision is not tagged, then we take the last tagged version number and increment it to get a minimum target version.

We then walk git history back to the last release. Within each commit we look for a Sem-Ver: pseudo header, and if found parse it looking for keywords. Unknown symbols are not an error (so that folk can’t wedge pbr or break their tree), but we will emit an info level warning message. Known symbols: feature, api-break, deprecation, bugfix. A missing Sem-Ver line is equivalent to Sem-Ver: bugfix. The bugfix symbol causes a patch level increment to the version. The feature and deprecation symbols cause a minor version increment. The api-break symbol causes a major version increment.

If postversioning is in use, we use the resulting version number as the target version.

If preversioning is in use we check that the version set in the metadata section of setup.cfg is greater than the version we infer using the above method. If the inferred version is greater than the preversioning value we raise an error, otherwise we use the version from setup.cfg as the target.

We then generate dev version strings based on the commits since the last release and include the current git sha to disambiguate multiple dev versions with the same number of commits since the release.

Note

pbr expects git tags to be signed for use in calculating versions

The versions are expected to be compliant with Linux/Python Compatible Semantic Versioning 3.0.0.

The version.SemanticVersion class can be used to query versions of a package and present it in various forms - debian_version(), release_string(), rpm_string(), version_string(), or version_tuple().

AUTHORS and ChangeLog

Why keep an AUTHORS or a ChangeLog file when git already has all of the information you need? AUTHORS generation supports filtering/combining based on a standard .mailmap file.

Manifest

Just like AUTHORS and ChangeLog, why keep a list of files you wish to include when you can find many of these in git. MANIFEST.in generation ensures almost all files stored in git, with the exception of .gitignore, .gitreview and .pyc files, are automatically included in your distribution. In addition, the generated AUTHORS and ChangeLog files are also included. In many cases, this removes the need for an explicit ‘MANIFEST.in’ file

Sphinx Autodoc

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.

See the pbr section for details on configuring your project for autodoc.

Requirements

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 populate a virtualenv for testing or to just install everything you need. Duplicating the information, though, is super lame. To solve this issue, pbr will let you use requirements.txt-format files to describe the requirements for your project and will then parse these files, split them up appropriately, and inject them into the install_requires, tests_require and/or dependency_links arguments to setup. Voila!

You can also have a requirement file for each specific major version of Python. If you want to have a different package list for Python 3 then just drop a requirements-py3.txt and it will be used instead.

Finally, it is possible to specify groups of optional dependencies, or “extra” requirements, in your setup.cfg rather than setup.py.

long_description

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.

Usage

pbr is a setuptools plugin and so to use it you must use setuptools and call setuptools.setup(). While the normal setuptools facilities are available, pbr makes it possible to express them through static data files.

setup.py

pbr only requires a minimal setup.py file compared to a standard setuptools project. This is because most configuration is located in static configuration files. This recommended minimal setup.py file should look something like this:

#!/usr/bin/env python

from setuptools import setup

setup(
    setup_requires=['pbr>=1.9', 'setuptools>=17.1'],
    pbr=True,
)

Note

It is necessary to specify pbr=True to enabled pbr functionality.

Note

While one can pass any arguments supported by setuptools to setup(), any conflicting arguments supplied in setup.cfg will take precedence.

setup.cfg

The setup.cfg file is an ini-like file that can mostly replace the setup.py file. It is based on the distutils2 setup.cfg file. 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 = openstack-dev@lists.openstack.org
summary = OpenStack's setup automation in a reusable form
description-file = README
home-page = https://launchpad.net/pbr
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 =
    pbr
data_files =
    etc/pbr = etc/*
    etc/init =
        pbr.packaging.conf
        pbr.version.conf

[entry_points]
console_scripts =
    pbr = pbr.cmd:main
pbr.config.drivers =
    plain = pbr.cfg.driver:Plain

pbr provides its own section in these documents, ostensibly called pbr, and provides a custom version of Sphinx’s build_sphinx section. Most other sections are provided by setuptools and may influence either the build itself or the output of various `setuptools commands`__. The remaining sections are provided by libraries that provide setuptools extensions, such as extract_mesages (provided by `Babel`__). Some of these are described below.

Note

Comments may be used in setup.cfg, however all comments should start with a # and may be on a single line, or in line, with at least one white space character immediately preceding the #. Semicolons are not a supported comment delimiter. For instance:

[section]
# A comment at the start of a dedicated line
key =
    value1 # An in line comment
    value2
    # A comment on a dedicated line
    value3

files

The files section defines the install location of files in the package using three fundamental keys: packages, namespace_packages, and data_files.

packages

A list of top-level packages that should be installed. The behavior of packages is similar to setuptools.find_packages in that it recurses the python package hierarchy below the given top level and installs all of it. If packages is not specified, it defaults to the value of the name field given in the [metadata] section.

namespace_packages

Similar to packages, but is a list of packages that provide namespace packages.

data_files

A list of files to be installed. The format is an indented block that contains key value pairs which specify target directory and source file to install there. More than one source file for a directory may be indicated with a further indented list. Source files are stripped of leading directories. Additionally, pbr supports a simple file globbing syntax for installing entire directory structures, thus:

[files]
data_files =
    etc/pbr = etc/pbr/*
    etc/neutron =
        etc/api-paste.ini
        etc/dhcp-agent.ini
    etc/init.d = neutron.init

will result in /etc/neutron containing api-paste.ini and dhcp-agent.ini, both of which pbr will expect to find in the etc directory in the root of the source tree. Additionally, neutron.init from that dir will be installed in /etc/init.d. All of the files and directories located under etc/pbr in the source tree will be installed into /etc/pbr.

Note that this behavior is relative to the effective root of the environment into which the packages are installed, so depending on available permissions this could be the actual system-wide /etc directory or just a top-level etc subdirectory of a virtualenv.

pbr

The pbr section controls pbr specific options and behaviours.

autodoc_tree_index_modules

A boolean option controlling whether pbr should generate an index of modules using sphinx-apidoc. By default, all files except setup.py are included, but this can be overridden using the autodoc_tree_excludes option.

autodoc_tree_excludes

A list of modules to exclude when building documentation using sphinx-apidoc. Defaults to [setup.py]. Refer to the sphinx-apidoc man page for more information.

autodoc_index_modules

A boolean option controlling whether pbr should itself generates documentation for Python modules of the project. By default, all found Python modules are included; some of them can be excluded by listing them in autodoc_exclude_modules.

autodoc_exclude_modules

A list of modules to exclude when building module documentation using pbr. fnmatch style pattern (e.g. myapp.tests.*) can be used.

api_doc_dir

A subdirectory inside the build_sphinx.source_dir where auto-generated API documentation should be written, if autodoc_index_modules is set to True. Defaults to "api".

Note

When using autodoc_tree_excludes or autodoc_index_modules you may also need to set exclude_patterns in your Sphinx configuration file (generally found at doc/source/conf.py in most OpenStack projects) otherwise Sphinx may complain about documents that are not in a toctree. This is especially true if the [sphinx_build] warning-is-error option is set. See the Sphinx build configuration file documentation for more information on configuring Sphinx.

Changed in version 2.0: The pbr section used to take a warnerrors option that would enable the -W (Turn warnings into errors.) option when building Sphinx. This feature was broken in 1.10 and was removed in pbr 2.0 in favour of the [build_sphinx] warning-is-error provided in Sphinx 1.5+.

build_sphinx

The build_sphinx section is a version of the build_sphinx setuptools plugin provided with Sphinx. This plugin extends the original plugin to add the following:

  • Automatic generation of module documentation using the apidoc__ tool

  • Automatic configuration of the project, version and release settings using information from pbr itself

  • Support for multiple builders using the builders configuration option

    Note

    Sphinx 1.6 adds support for multiple builders using the default builder option. You should refer to this file for more information.

The version of build_sphinx provided by pbr provides a single additional option.

builders

A space or comma separated list of builders to run. For example, to build both HTML and man page documentation, you would define the following in your setup.cfg:

[build_sphinx]
builders = html,man
source-dir = doc/source
build-dir = doc/build
all-files = 1

source_dir

The path to the source directory where the Sphinx documentation tree is.

For information on the remaining options, refer to the `Sphinx documentation`__. In addition, the autodoc_index_modules, autodoc_tree_index_modules, autodoc_exclude_modules and autodoc_tree_excludes options in the pbr section will affect the output of the automatic module documentation generation.

Changed in version 3.0: The build_sphinx plugin used to default to building both HTML and man page output. This is no longer the case, and you should explicitly set builders to html man if you wish to retain this behavior.

entry_points

The entry_points section defines entry points for generated console scripts and python libraries. This is actually provided by `setuptools`__ but is documented here owing to its importance.

The general syntax of specifying entry points is a top level name indicating the entry point group name, followed by one or more key value pairs naming the entry point to be installed. For instance:

[entry_points]
console_scripts =
    pbr = pbr.cmd:main
pbr.config.drivers =
    plain = pbr.cfg.driver:Plain
    fancy = pbr.cfg.driver:Fancy

Will cause a console script called pbr to be installed that executes the main function found in pbr.cmd. Additionally, two entry points will be installed for pbr.config.drivers, one called plain which maps to the Plain class in pbr.cfg.driver and one called fancy which maps to the Fancy class in pbr.cfg.driver.

Requirements

Requirement files should be given one of the below names. This order is also the order that the requirements are tried in (where N is the Python major version number used to install the package):

  • requirements-pyN.txt
  • tools/pip-requires-py3
  • requirements.txt
  • tools/pip-requires

Only the first file found is used to install the list of packages it contains.

Note

The ‘requirements-pyN.txt’ file is deprecated - ‘requirements.txt’ should be universal. You can use Environment markers for this purpose.

Extra requirements

Groups of optional dependencies, or “extra” requirements, can be described in your setup.cfg, rather than needing to be added to setup.py. An example (which also demonstrates the use of environment markers) is shown below.

Environment markers

Environment markers are conditional dependencies which can be added to the requirements (or to a group of extra requirements) automatically, depending on the environment the installer is running in. They can be added to requirements in the requirements file, or to extras defined in setup.cfg, but the format is slightly different for each.

For requirements.txt:

argparse; python_version=='2.6'

This will result in the package depending on argparse only if it’s being installed into Python 2.6

For extras specified in setup.cfg, add an extras section. For instance, to create two groups of extra requirements with additional constraints on the environment, you can use:

[extras]
security =
    aleph
    bet:python_version=='3.2'
    gimel:python_version=='2.7'
testing =
    quux:python_version=='2.7'

Testing

pbr overrides the setuptools hook test (i.e. setup.py test). The following sequence is followed:

  1. If a .testr.conf file exists and testrepository is installed, pbr will use it as the test runner. See the testr documentation for more details.

    Note

    This is separate to setup.py testr (note the extra r) which is provided directly by the testrepository package. Be careful as there is some overlap of command arguments.

  2. Although deprecated, if [nosetests] is defined in setup.cfg and nose is installed, the nose runner will be used.

  3. In other cases no override will be installed and the test command will revert to setuptools.

A typical usage would be in tox.ini such as:

[tox]
minversion = 2.0
skipsdist = True
envlist = py33,py34,py35,py26,py27,pypy,pep8,docs

[testenv]
usedevelop = True
setenv =
  VIRTUAL_ENV={envdir}
  CLIENT_NAME=pbr
deps = .
     -r{toxinidir}/test-requirements.txt
commands =
  python setup.py test --testr-args='{posargs}'

The argument --coverage will set PYTHON to coverage run to produce a coverage report. --coverage-package-name can be used to modify or narrow the packages traced.

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