Munin contributed plugins

#!/usr/bin/env python3

# -*- python -*-

"""

=head1 INTRODUCTION

Plugin to monitor the MySQL audit log connection count

=head1 APPLICABLE SYSTEMS

MySQL needs to be configured manually in order to enable the audit log. This

can be done as follows:

=over 2

      plugin-load = server_audit=server_audit.so

      server_audit_events = connect

      server_audit_output_type=file

      server_audit_file_path = /var/log/mysql/audit.log

      server_audit_file_rotate_size = 512M

      server_audit_logging = ON

      server_audit_file_rotations = 5

=back

=head1 INSTALLATION

Place in /etc/munin/plugins/ (or link it there using ln -s)

=head1 CONFIGURATION

Add this to your /etc/munin/plugin-conf.d/munin-node:

=over 2

      [mysql_audit]

      user mysql

      env.logfile /var/log/mysql/audit.log

      env.sorted 1 # sort output (if not: unsorted)

      env.toplist 10 # only the top 10 (if unset: all of them). implies sorted

=back

=head1 HISTORY

2017-11-03: v 1.0 Bert Van de Poel <bert@bhack.net>: created

2020-07-19: v 1.1 pcy <pcy@ulyssis.org>: added config options

=head1 USAGE

Parameters understood:

  config   (required)

  autoconf (optional - used by munin-config)

=head1 MAGIC MARKERS

#%# family=auto

#%# capabilities=autoconf

"""

from datetime import datetime, timedelta, timezone

import operator

import os

import struct

import sys

def weakbool(x):

    return x.lower().strip() in {'true', 'yes', 'y', '1'}

logfile = os.getenv('logfile', '/var/log/mysql/audit.log')

toplist = int(os.getenv('toplist', '0'))

sortlist = weakbool(os.getenv('sorted', 'N')) or toplist > 0

STATEFILE = os.getenv('MUNIN_STATEFILE')

def loadstate():

    if not os.path.isfile(STATEFILE):

        return None

    with open(STATEFILE, 'rb') as f:

        tstamp = struct.unpack('d', f.read())[0]

        return datetime.fromtimestamp(tstamp, tz=timezone.utc)

def savestate(state):

    with open(STATEFILE, 'wb') as f:

        f.write(struct.pack('d', state.timestamp()))

def reverse_lines(filename, BUFSIZE=4096):

    with open(filename, "r") as f:

        f.seek(0, 2)

        p = f.tell()

        remainder = ""

        while True:

            sz = min(BUFSIZE, p)

            p -= sz

            f.seek(p)

            buf = f.read(sz) + remainder

            if '\n' not in buf:

                remainder = buf

            else:

                i = buf.index('\n')

                for L in buf[i + 1:].split("\n")[::-1]:

                    yield L

                remainder = buf[:i]

            if p == 0:

                break

        yield remainder

def get_data(do_save=True):

    occurrences = {}

    begin = datetime.now(timezone.utc)

    begin_local = datetime.now()

    state = loadstate()

    if state is None:

        # need to do something here to prevent reading indefinitely

        state = begin - timedelta(minutes=5)

    for line in reverse_lines(logfile):

        if ',CONNECT,' not in line:

            continue

        splitted = line.split(',')

        key = splitted[2]

        date = datetime.strptime(splitted[0], '%Y%m%d %H:%M:%S')

        # hack to add timezone data to the datetime

        date = begin + (date - begin_local)

        if date < state:

            break

        occurrences[key] = occurrences.get(key, 0) + 1

    if do_save:

        savestate(begin)

    return occurrences

def autoconf():

    print("no (logfile not found)" if os.path.isfile(logfile) else "yes")

def configure():

    print('graph_title MySQL Audit connect count')

    print('graph_vlabel Connections')

    print('graph_category mysql')

    occurrences = get_data(False)

    occitems = occurrences.items()

    occitems = sorted(occitems, key=operator.itemgetter(1 if sortlist else 0),

                      reverse=sortlist)

    if toplist > 0:

        occitems = occitems[:toplist]

    for key, value in occitems:

        print('{}.label {}'.format(key.lower(), key))

        print('{}.type GAUGE'.format(key.lower()))

        print('{}.draw AREASTACK'.format(key.lower()))

def fetch():

    occurrences = get_data()

    occitems = occurrences.items()

    occitems = sorted(occitems, key=operator.itemgetter(1 if sortlist else 0),

                      reverse=sortlist)

    if toplist > 0:

        occitems = occitems[:toplist]

    for key, value in occitems:

        print('{}.value {}'.format(key, value))

if len(sys.argv) == 2 and sys.argv[1] == "autoconf":

    autoconf()

elif len(sys.argv) == 2 and sys.argv[1] == "config":

    configure()

else:

    fetch()

# flake8: noqa: E265