Implement app's update checking by git tagging

git-update-check.py

import re
import requests
from distutils.version import LooseVersion

# we are smart client and do not support dumb protocal
# protocol document: https://github.com/git/git/blob/master/Documentation/technical/http-protocol.txt

class GitHttpError(Exception):
    pass


_ref_tag = re.compile(r'^[0-9a-f]+ refs/tags/(.+)$')


def get_git_repo_tags(url):
    """Fetch tags from git repository through HTTP(S) protocol.
    :param url: something like "https://gitlab.com/test/test.git"
    :return: a list of tags in C locale ordering, you may consider
    using distutils.version.LooseVersion to compare"""
    if url.endswith('/'):
        url = url[:-1]
    url += '/info/refs?service=git-upload-pack'
    ref_tag = re.compile(r'^[0-9a-f]+ refs/tags/(.+)$')
    
    r = requests.get(url, headers={'User-Agent': 'git-http-ls-remote'})
    if not r.ok:
        raise GitHttpError('code: %s' % r.status_code)
    lines = r.text.split('\n')
    assert lines.pop() == '0000'
    
    l = lines.pop(0)
    if not re.match(r'^[0-9a-f]{4}# service=git-upload-pack', l):
        raise GitHttpError('invalid HTTP response: %s' % l)
    # this line looks like "000000d1464... HEAD\x00multi_ack ... agent=git/2.6.1"
    if '\x00' in lines[0]:
        lines.pop(0)
    
    tags = map(lambda x: x.group(1),
               filter(None, (_ref_tag.search(i) for i in lines)))
    return [i for i in tags if not i.endswith('^{}')]


repo_url = 'https://gitlab.com/krrr/Hazama.git'
newest_ver = max(map(LooseVersion, get_git_repo_tags(repo_url)))
print(newest_ver)