check_time_http

#!/usr/bin/env python3
#
# MIT License
# Copyright (c) 2019 Dick Visser
#
# https://github.com/dnmvisser/nagios_check_time_by_http_date
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import argparse
import sys
import requests
import datetime
import pytz
import email.utils
import urllib3

def nagios_exit(message, code):
    print(message)
    sys.exit(code)

# start with clean slate
ok_msg = []
warn_msg = []
crit_msg = []
unknown_msg = []

try:
    parser = argparse.ArgumentParser(description=
        'Check time offset of the HTTP "Date" response header against the local time')
    parser.add_argument('--url', '-u',
                        help='the URL to check', required=True)
    parser.add_argument('--useragent', '-a',
                        help='the User-Agent string to use', required=False, default='check_time_http')
    # https://kantarainitiative.github.io/SAMLprofiles/saml2int.html#_clock_skew
    parser.add_argument('--warn', '-w',
                        help='Offset to result in warning (seconds, default 180)',
                        required=False, type=int, default=180)
    parser.add_argument('--crit', '-c',
                        help='Offset to result in critical (seconds, default 300)',
                        required=False, type=int, default=300)
    parser.add_argument('--timeout', '-t',
                        help='Timeout of the HTTP request (seconds)',
                        required=False, type=int)
    parser.add_argument('--verbose', '-v',
                        help='Return verbose output',
                        required=False, dest='verbose', action='store_true')

    verify_parser = parser.add_mutually_exclusive_group(required=False)
    verify_parser.add_argument('--verify',
            dest='verify', action='store_true',
            help="Verify SSL certificate (default)")
    verify_parser.add_argument('--no-verify',
            dest='verify', action='store_false',
            help="Do not verify SSL certificate")
    parser.set_defaults(verify=True)


    args = parser.parse_args()

    url = args.url
    useragent = args.useragent
    warn = args.warn
    crit = args.crit
    timeout = args.timeout
    verify = args.verify
    verbose = args.verbose

    urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
    req = requests.head(
            url,
            timeout=timeout,
            verify=verify,
            headers={'User-Agent': useragent}
            )

    # Date with time zone
    utc_now = pytz.utc.localize(datetime.datetime.utcnow().replace(microsecond=0))

    # this is case insensitive
    if 'date' in req.headers:
        http_date = email.utils.parsedate_to_datetime(req.headers['date'])
        offset = int((http_date - utc_now).total_seconds())
        message = "Offset is {0} seconds".format(offset)
        if(verbose):
            message += ", URL: {0}".format(url)
            message += ", local date: {0}".format(utc_now)
            message += ", HTTP headers: {0}".format(req.headers)

        if(abs(offset) > crit):
            crit_msg.append(message)
        elif(abs(offset) > warn):
            warn_msg.append(message)
        else:
            ok_msg.append(message)
    else:
        unknown_msg.append("No Date header detected for {0}".format(url))
except Exception as e:
    unknown_msg.append("{0}.".format(e))

# Exit with accumulated message(s)
if unknown_msg:
    nagios_exit("UNKNOWN: " + ' '.join(unknown_msg), 3)
elif crit_msg:
    nagios_exit("CRITICAL: " + ' '.join(crit_msg + warn_msg), 2)
elif warn_msg:
    nagios_exit("WARNING: " + ' '.join(warn_msg), 1)
else:
    nagios_exit("OK: " + ' '.join(ok_msg), 0)