check_graylog_lag

#!/usr/bin/env python
# coding: utf-8

# Copyright Ilya Margolin 2015
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Check graylog lag (and general availability), by searching for recent messages and inspecting the
timestamp of latest message.
"""

import datetime
import sys
import socket
import argparse
import logging
import requests
import nagiosplugin
import dateutil.parser
from nagiosplugin.state import Critical

HOSTNAME = socket.gethostname()
SEARCH_URL_TEMPLATE = 'http://%s:12900/search/universal/relative?query=*&range=%i&limit=1'  # noqa
_log = logging.getLogger('nagiosplugin')


class ConnectionContext(nagiosplugin.context.ScalarContext):
    def evaluate(self, metric, resource):
        if resource.connection_error:
            return nagiosplugin.result.Result(Critical, str(resource.connection_error.message))
        else:
            return super(ConnectionContext, self).evaluate(metric, resource)


class Graylog(nagiosplugin.Resource):
    def __init__(self):
        self.horizont = None
        self.graylog = None
        self.auth = None
        self.connection_error = None
        self.timeout = None
        self.connection_errors_are_critical = None

    def probe(self):
        return [nagiosplugin.Metric('lag', self.get_lag(), 's', context='lag')]

    def get_lag(self):
        search_url = SEARCH_URL_TEMPLATE % (self.graylog, self.horizont)
        _log.info('GET %s', search_url)
        _log.info('	with auth: %s', self.auth)
        try:
            r = requests.get(
                search_url,
                auth=self.auth,
                headers={'Accept': 'application/json'},
                timeout=self.timeout
            )
        except IOError, e:
            if self.connection_errors_are_critical:
                self.connection_error = e
                return float('inf')
            else:
                raise

        _log.info('Response status code: %s', r.status_code)
        _log.info('Response content: %s', r.content)
        r.raise_for_status()
        r.encoding = 'utf-8'
        try:
            json = r.json()
        except TypeError:  # requests < 1.0.0 compatibility
            json = r.json
        messages = json['messages']
        if not messages:
            _log.warn('no messages found (searched in last %s seconds)', self.horizont)
            return self.horizont
        ts = messages[0]['message']['timestamp']
        parsed_ts = dateutil.parser.parse(ts)
        now_tz = datetime.datetime.now(parsed_ts.tzinfo)
        td = (now_tz - parsed_ts)
        # total_seconds python 2.6 compatibility
        total_seconds = (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / 10 ** 6
        lag = int(total_seconds)

        return lag


@nagiosplugin.guarded
def main():
    argp = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    argp.add_argument('-w', '--warning', metavar='RANGE', default='0:300',
                      help='return warning if lag is outside RANGE')
    argp.add_argument('-c', '--critical', metavar='RANGE', default='0:600',
                      help='return critical if lag is outside RANGE')
    argp.add_argument('-H', '--horizont', '--horizon', metavar='seconds', type=int, default=3600,
                      help='How far back to search for messages')
    argp.add_argument('-g', '--graylog', metavar='hostname', default=HOSTNAME,
                      help='graylog hostname to check')
    argp.add_argument('-a', '--auth', default=None,
                      help='username:password, basic auth')
    argp.add_argument('-v', '--verbose', action='count', default=0,
                      help='increase output verbosity (use up to 3 times)')
    argp.add_argument('--connection-errors-are-critical', action='count', default=0,
                      help='Return CRITICAL for timeouts and connection errors')
    argp.add_argument('-t', '--timeout', type=float, metavar='seconds', default=10,
                      help='Connection timeout')
    args = argp.parse_args()

    resource = Graylog()
    resource.graylog = args.graylog
    resource.horizont = args.horizont
    resource.timeout = args.timeout
    resource.connection_errors_are_critical = args.connection_errors_are_critical
    if args.auth:
        resource.auth = tuple(args.auth.split(':'))

    check = nagiosplugin.Check(
        resource,
        ConnectionContext('lag', args.warning, args.critical)
    )
    check.main(verbose=args.verbose)


if __name__ == '__main__':
    main()