#!/usr/bin/python3

# Monitor chronyd
#
# Copyright 2019 Bernd Zeimetz <bernd@bzed.de>
#
# 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.

from subprocess import Popen, PIPE
import optparse
import sys

broken_example = """Reference ID    : 00000000 ()
Stratum         : 0
Ref time (UTC)  : Thu Jan 01 00:00:00 1970
System time     : 0.000000000 seconds fast of NTP time
Last offset     : +0.000000000 seconds
RMS offset      : 0.000000000 seconds
Frequency       : 8.769 ppm fast
Residual freq   : +0.000 ppm
Skew            : 0.000 ppm
Root delay      : 1.000000000 seconds
Root dispersion : 1.000000000 seconds
Update interval : 0.0 seconds
Leap status     : Not synchronised
"""

NAGIOS_STATUS = {
    "OK": 0,
    "WARNING": 1,
    "CRITICAL": 2,
    "UNKNOWN": 3
}

parser = optparse.OptionParser()
parser.set_usage("%prog [options]")
parser.add_option(
    "-w", "--warning", dest="warning", metavar="WARNING",
    type="int", default="1000",
    help="time differences in ms (warning)"
)
parser.add_option(
    "-c", "--critical", dest="critical", metavar="CRITICAL",
    type="int", default="3000",
    help="time differences in ms (critical)"
)
parser.add_option(
    "-W", "--stratum-warning", dest="stratum_warning",
    metavar="STRATUM_WARNING",
    type="int", default="3",
    help="maximum stratum level (warning)"
)
parser.add_option(
    "-C", "--stratum-critical", dest="stratum_critical",
    metavar="STRATUM_CRITICAL",
    type="int", default="5",
    help="maximum stratum level (critical)"
)
(options, args) = parser.parse_args()

chronyc = Popen(
    ['chronyc', 'tracking'],
    stdin=PIPE, stdout=PIPE, stderr=PIPE,
    bufsize=-1
)
output, error = chronyc.communicate()

if chronyc.returncode > 0:
    print(("chronyc failed: {}".format(output)))
    sys.exit(NAGIOS_STATUS['CRITICAL'])

output = output.decode().split('\n')
parsed_output = {}

for line in output:
    if ':' not in line:
        continue
    line = line.split(':')
    key = line[0]
    value = ':'.join(line[1:])
    key = key.strip()
    value = value.strip()
    key = key.replace('(', '')
    key = key.replace(')', '')
    key = key.replace(' ', '_')
    key = key.lower()

    parsed_output[key] = value

if '00000000' in parsed_output['reference_id']:
    print("chrony failed to connect to NTP server.")
    sys.exit(NAGIOS_STATUS['CRITICAL'])

if int(parsed_output['stratum']) > options.stratum_critical:
    print((
        "chrony stratum too high: {} > {}".format(
            parsed_output['stratum'],
            options.stratum_critical
        )
    ))
    sys.exit(NAGIOS_STATUS['CRITICAL'])

if int(parsed_output['stratum']) > options.stratum_warning:
    print((
        "chrony stratum too high: {} > {}".format(
            parsed_output['stratum'],
            options.stratum_warning
        )
    ))
    sys.exit(NAGIOS_STATUS['WARNING'])

system_time = parsed_output['system_time'].split(' ')
system_time_diff_ms = float(system_time[0]) * 1000
system_time_desc = ' '.join(system_time[1:])

if (system_time_diff_ms > options.critical):
    print((
        "chrony system time {}ms {}. ({}ms > {}ms)".format(
            system_time_diff_ms,
            system_time_desc,
            system_time_diff_ms,
            options.critical
        )
    ))
    sys.exit(NAGIOS_STATUS['CRITICAL'])

if (system_time_diff_ms > options.warning):
    print((
        "chrony system time {}ms {}. ({}ms > {}ms)".format(
            system_time_diff_ms,
            system_time_desc,
            system_time_diff_ms,
            options.warning
        )
    ))
    sys.exit(NAGIOS_STATUS['WARNING'])


print((
    "chrony OK: System Time {}, Stratum {}".format(
        parsed_output['system_time'],
        parsed_output['stratum'],
    )
))
sys.exit(NAGIOS_STATUS['OK'])