version.py

#!/usr/bin/env python
# Module for detecting build version from Git tags.
# Adapted from: https://gist.github.com/dcreager/300803
#
__all__ = ("get_git_version")

from subprocess import Popen, PIPE


def call_git_describe(abbrev=4, prefix='v'):
    try:
        p = Popen(['git', 'describe', '--abbrev=%d' % abbrev, 
                '--match=%s*' % prefix],
                stdout=PIPE, stderr=PIPE)
        p.stderr.close()
        line = p.stdout.readlines()[0]
        return line.strip()[len(prefix):]

    except:
        return None


def read_release_version():
    try:
        f = open("RELEASE-VERSION", "r")

        try:
            version = f.readlines()[0]
            return version.strip()

        finally:
            f.close()

    except:
        return None


def write_release_version(version):
    f = open("RELEASE-VERSION", "w")
    f.write("%s\n" % version)
    f.close()


def get_git_version(fallback='0.0.0', abbrev=4, prefix='v'):
    # Read in the version that's currently in RELEASE-VERSION.
    release_version = read_release_version()

    # First try to get the current version using "git describe".
    version = call_git_describe(abbrev)

    # If that doesn't work, fall back on the value that's in
    # RELEASE-VERSION.
    if version is None:
        version = release_version

    # If still no version, use the given fallback value
    if version is None:
        version = fallback

    # If we still don't have anything, that's an error.
    if version is None:
        raise ValueError("Cannot find the version number!")

    # If the current version is different from what's in the
    # RELEASE-VERSION file, update the file to be current.
    if version != release_version:
        write_release_version(version)

    # Finally, return the current version.
    return version


if __name__ == "__main__":
    print get_git_version()