--version support in a Python program built with Pants

Question

How can I get Pants to store the output of git describe somewhere in my .pex file so that I can access it from the Python code I'm writing?

Basically I want to be able to clone my project and do this:

1. ./pants binary px
2. Distribute the resulting dist/px.pex to somebody
3. That somebody should be able to do px.pex --version and get a printout of whatever git describe said when I built the .pex in step one.

Help!

Answer 1

Turns out pex already does git describe on build. The result it stores in a PEX-INFO file in the root of the .pex file. So to read it, I did this:

def get_version():
    """Extract version string from PEX-INFO file"""
    my_pex_name = os.path.dirname(__file__)
    zip = zipfile.ZipFile(my_pex_name)
    with zip.open("PEX-INFO") as pex_info:
        return json.load(pex_info)['build_properties']['tag']

This is good enough IMO, but there are also drawbacks. If somebody has an improved answer I'm prepared to switch to that one as the accepted one.

Outages with this one:

• Relies on relative paths to locate PEX-INFO, would be better if there was some kind of API call for this.
• No way to customize how the version number is computed; I'd like to do git describe --dirty for example.