Check SSL certificate expiration with Python

sslcheck.py

#!/usr/bin/env python3

import ssl
import OpenSSL  # pip install pyopenssl
from datetime import datetime


def get_cert_expiration(domain):
    cert = ssl.get_server_certificate((domain, 443))
    x509 = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM, cert)
    expiration = datetime.strptime(x509.get_notAfter().decode("utf-8"),"%Y%m%d%H%M%SZ")
    return str(expiration)


def start():
    domain_list = [
        'google.com',
        'twitter.com'
    ]
    for domain in domain_list:
        print(f'checking domain {domain}')
        result = get_cert_expiration(domain)
        print(result)


if __name__ == '__main__':
    start()