The Versioneer

• like a rocketeer, but for versions!
• https://github.com/warner/python-versioneer
• Brian Warner
• License: Public Domain
• Compatible With: python2.6, 2.7, 3.2, 3.3, 3.4, and pypy
• 
• 

This is a tool for managing a recorded version number in distutils-based python projects. The goal is to remove the tedious and error-prone "update the embedded version string" step from your release process. Making a new release should be as easy as recording a new tag in your version-control system, and maybe making new tarballs.

Quick Install

• pip install versioneer to somewhere to your $PATH
• run versioneer-installer in your source tree: this installs versioneer.py
• follow the instructions below (also in the versioneer.py docstring)

Version Identifiers

Source trees come from a variety of places:

• a version-control system checkout (mostly used by developers)
• a nightly tarball, produced by build automation
• a snapshot tarball, produced by a web-based VCS browser, like github's "tarball from tag" feature
• a release tarball, produced by "setup.py sdist", distributed through PyPI

Within each source tree, the version identifier (either a string or a number, this tool is format-agnostic) can come from a variety of places:

• ask the VCS tool itself, e.g. "git describe" (for checkouts), which knows about recent "tags" and an absolute revision-id
• the name of the directory into which the tarball was unpacked
• an expanded VCS keyword ($Id$, etc)
• a _version.py created by some earlier build step

For released software, the version identifier is closely related to a VCS tag. Some projects use tag names that include more than just the version string (e.g. "myproject-1.2" instead of just "1.2"), in which case the tool needs to strip the tag prefix to extract the version identifier. For unreleased software (between tags), the version identifier should provide enough information to help developers recreate the same tree, while also giving them an idea of roughly how old the tree is (after version 1.2, before version 1.3). Many VCS systems can report a description that captures this, for example 'git describe --tags --dirty --always' reports things like "0.7-1-g574ab98-dirty" to indicate that the checkout is one revision past the 0.7 tag, has a unique revision id of "574ab98", and is "dirty" (it has uncommitted changes.

The version identifier is used for multiple purposes:

• to allow the module to self-identify its version: myproject.__version__
• to choose a name and prefix for a 'setup.py sdist' tarball

Theory of Operation

Versioneer works by adding a special _version.py file into your source tree, where your __init__.py can import it. This _version.py knows how to dynamically ask the VCS tool for version information at import time. However, when you use "setup.py build" or "setup.py sdist", _version.py in the new copy is replaced by a small static file that contains just the generated version data.

_version.py also contains $Revision$ markers, and the installation process marks _version.py to have this marker rewritten with a tag name during the "git archive" command. As a result, generated tarballs will contain enough information to get the proper version.

Installation

First, decide on values for the following configuration variables:

• VCS: the version control system you use. Currently accepts "git".

• versionfile_source:

  A project-relative pathname into which the generated version strings should be written. This is usually a _version.py next to your project's main __init__.py file, so it can be imported at runtime. If your project uses src/myproject/__init__.py, this should be src/myproject/_version.py. This file should be checked in to your VCS as usual: the copy created below by setup.py versioneer will include code that parses expanded VCS keywords in generated tarballs. The 'build' and 'sdist' commands will replace it with a copy that has just the calculated version string.

  This must be set even if your project does not have any modules (and will therefore never import _version.py), since "setup.py sdist" -based trees still need somewhere to record the pre-calculated version strings. Anywhere in the source tree should do. If there is a __init__.py next to your _version.py, the setup.py versioneer command (described below) will append some __version__-setting assignments, if they aren't already present.

• versionfile_build:

  Like versionfile_source, but relative to the build directory instead of the source directory. These will differ when your setup.py uses 'package_dir='. If you have package_dir={'myproject': 'src/myproject'}, then you will probably have versionfile_build='myproject/_version.py' and versionfile_source='src/myproject/_version.py'.

  If this is set to None, then setup.py build will not attempt to rewrite any _version.py in the built tree. If your project does not have any libraries (e.g. if it only builds a script), then you should use versionfile_build = None and override distutils.command.build_scripts to explicitly insert a copy of versioneer.get_version() into your generated script.

• tag_prefix:

  a string, like 'PROJECTNAME-', which appears at the start of all VCS tags. If your tags look like 'myproject-1.2.0', then you should use tag_prefix='myproject-'. If you use unprefixed tags like '1.2.0', this should be an empty string.

• parentdir_prefix:

  a string, frequently the same as tag_prefix, which appears at the start of all unpacked tarball filenames. If your tarball unpacks into 'myproject-1.2.0', this should be 'myproject-'.

This tool provides one script, named versioneer-installer. That script does one thing: write a copy of versioneer.py into the current directory.

To versioneer-enable your project:

• 1: Run versioneer-installer to copy versioneer.py into the top of your source tree.

• 2: add the following lines to the top of your setup.py, with the configuration values you decided earlier:

    import versioneer
    versioneer.VCS = 'git'
    versioneer.versionfile_source = 'src/myproject/_version.py'
    versioneer.versionfile_build = 'myproject/_version.py'
    versioneer.tag_prefix = '' # tags are like 1.2.0
    versioneer.parentdir_prefix = 'myproject-' # dirname like 'myproject-1.2.0'
  

• 3: add the following arguments to the setup() call in your setup.py:

    version=versioneer.get_version(),
    cmdclass=versioneer.get_cmdclass(),
  

• 4: now run setup.py versioneer, which will create _version.py, and will modify your __init__.py (if one exists next to _version.py) to define __version__ (by calling a function from _version.py). It will also modify your MANIFEST.in to include both versioneer.py and the generated _version.py in sdist tarballs.

• 5: commit these changes to your VCS. To make sure you won't forget, setup.py versioneer will mark everything it touched for addition.

Post-Installation Usage

Once established, all uses of your tree from a VCS checkout should get the current version string. All generated tarballs should include an embedded version string (so users who unpack them will not need a VCS tool installed).

If you distribute your project through PyPI, then the release process should boil down to two steps:

• 1: git tag 1.0
• 2: python setup.py register sdist upload

If you distribute it through github (i.e. users use github to generate tarballs with git archive), the process is:

• 1: git tag 1.0
• 2: git push; git push --tags

Currently, all version strings must be based upon a tag. Versioneer will report "unknown" until your tree has at least one tag in its history. This restriction will be fixed eventually (see issue #12).

Version-String Flavors

Code which uses Versioneer can learn about its version string at runtime by importing _version from your main __init__.py file and running the get_versions() function. From the "outside" (e.g. in setup.py), you can import the top-level versioneer.py and run get_versions().

Both functions return a dictionary with different keys for different flavors of the version string:

• ['version']: condensed tag+distance+shortid+dirty identifier. For git, this uses the output of git describe --tags --dirty --always but strips the tag_prefix. For example "0.11-2-g1076c97-dirty" indicates that the tree is like the "1076c97" commit but has uncommitted changes ("-dirty"), and that this commit is two revisions ("-2-") beyond the "0.11" tag. For released software (exactly equal to a known tag), the identifier will only contain the stripped tag, e.g. "0.11".

• ['full']: detailed revision identifier. For Git, this is the full SHA1 commit id, followed by "-dirty" if the tree contains uncommitted changes, e.g. "1076c978a8d3cfc70f408fe5974aa6c092c949ac-dirty".

Some variants are more useful than others. Including full in a bug report should allow developers to reconstruct the exact code being tested (or indicate the presence of local changes that should be shared with the developers). version is suitable for display in an "about" box or a CLI --version output: it can be easily compared against release notes and lists of bugs fixed in various releases.

In the future, this will also include a PEP-0440 -compatible flavor (e.g. 1.2.post0.dev123). This loses a lot of information (and has no room for a hash-based revision id), but is safe to use in a setup.py "version=" argument. It also enables tools like pip to compare version strings and evaluate compatibility constraint declarations.

The setup.py versioneer command adds the following text to your __init__.py to place a basic version in YOURPROJECT.__version__:

from ._version import get_versions
__version__ = get_versions()['version']
del get_versions

Updating Versioneer

To upgrade your project to a new release of Versioneer, do the following:

• install the new Versioneer (pip install -U versioneer or equivalent)
• re-run versioneer-installer in your source tree to replace your copy of versioneer.py
• edit setup.py, if necessary, to include any new configuration settings indicated by the release notes
• re-run setup.py versioneer to replace SRC/_version.py
• commit any changed files

Upgrading from 0.10 to 0.11

You must add a versioneer.VCS = "git" to your setup.py before re-running setup.py versioneer. This will enable the use of additional version-control systems (SVN, etc) in the future.

Upgrading from 0.11 to 0.12

Nothing special.

Future Directions

This tool is designed to make it easily extended to other version-control systems: all VCS-specific components are in separate directories like src/git/ . The top-level versioneer.py script is assembled from these components by running make-versioneer.py . In the future, make-versioneer.py will take a VCS name as an argument, and will construct a version of versioneer.py that is specific to the given VCS. It might also take the configuration arguments that are currently provided manually during installation by editing setup.py . Alternatively, it might go the other direction and include code from all supported VCS systems, reducing the number of intermediate scripts.

License

To make Versioneer easier to embed, all its code is hereby released into the public domain. The _version.py that it creates is also in the public domain.