git-cookie-authdaemon

#!/usr/bin/python
"""
Background daemon to refresh OAuth access tokens.
Tokens are written to ~/.git-credential-cache/cookie
Git config variable http.cookiefile is updated.
"""

import atexit
import cookielib
import json
import os
import subprocess
import sys
import time
import urllib2

REFRESH = 300  # seconds remaining when starting refresh

A = 'http://metadata/0.1/meta-data/service-accounts/default/acquire'
S = 'https://www.googleapis.com/auth/gerritcodereview'
COOKIE_JAR = None

def configure_git():
  global COOKIE_JAR

  dir = os.path.join(os.environ['HOME'], '.git-credential-cache')
  COOKIE_JAR = os.path.join(dir, 'cookie')

  if os.path.exists(dir):
    os.chmod(dir, 0700)
  else:
    os.mkdir(dir, 0700)
  subprocess.call([
    'git', 'config', '--global',
    'http.cookiefile', COOKIE_JAR
  ])

def acquire_token():
  return json.load(urllib2.urlopen(A + '?scopes=' + S))

def update_cookie():
  token = acquire_token()
  expires = token['expiresAt']

  tmp_jar = COOKIE_JAR + '.lock'
  cj = cookielib.MozillaCookieJar(tmp_jar)
  cj.set_cookie(cookielib.Cookie(
    version = 0,
    name = 'o',
    value = token['accessToken'],
    port = None,
    port_specified = False,
    domain = '.googlesource.com',
    domain_specified = True,
    domain_initial_dot = True,
    path = '/',
    path_specified = True,
    secure = True,
    expires = expires,
    discard = False,
    comment = None,
    comment_url = None,
    rest = None))
  cj.save()
  os.rename(tmp_jar, COOKIE_JAR)
  return expires

def cleanup():
  if COOKIE_JAR:
    for p in [COOKIE_JAR, COOKIE_JAR + '.lock']:
      if os.path.exists(p):
        os.remove(p)

def refresh_loop(expires):
  atexit.register(cleanup)
  expires = expires - REFRESH
  while True:
    now = time.time()
    while now < expires:
      time.sleep(expires - now)
      now = time.time()
    expires = update_cookie() - REFRESH

def main():
  configure_git()
  expires = update_cookie()

  if os.fork() > 0:
    sys.exit(0)

  os.chdir('/')
  os.setsid()
  os.umask(0)

  pid = os.fork()
  if pid > 0:
    print '%s PID %d' % (sys.argv[0], pid)
    sys.exit(0)

  refresh_loop(expires)

if __name__ == '__main__':
  main()