Checks the expiry of a cert from the a PKCS12 file and alerts using tunable warning period

PKCS12 Cert Expire Check

from OpenSSL.crypto import *
import time
import datetime

from optparse import OptionParser

parser = OptionParser()
parser.add_option("-f", "--file", dest="filename",
                  help="PKCS12/pfx file", metavar="FILE")
parser.add_option("-p", "--password",
                  dest="password",
                  help="password of PKCS12/pfx file")

(options, args) = parser.parse_args()

year = datetime.timedelta(days=365)
month = datetime.timedelta(weeks=4)
day = datetime.timedelta(days=1)

warn_period = month * 1

# open it, using password. Supply/read your own from stdin.
p12_file = open(options.filename, "rb")

p12 = load_pkcs12(p12_file.read(), options.password)
cert = p12.get_certificate()

not_after_date_string = cert.get_notAfter()
not_after_date = datetime.datetime.strptime(not_after_date_string, "%Y%m%d%H%M%SZ")

now = datetime.datetime.now()

difference = not_after_date - now

if difference <= warn_period:
    print "Oh heck!"