Munin contributed plugins

#!/usr/bin/env python3

# -*- python -*-

"""

=head1 INTRODUCTION

Plugin to monitor MySQL database disk usage per prefix. A prefix can be eg.

'user' for the databases 'user_testdb' and 'user_db2', as can be seen in

certain shared hosting setups.

=head1 APPLICABLE SYSTEMS

Local access to the database files is required (which are stored in

/var/lib/mysql by default).

=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_disk_by_prefix]

    user mysql

    env.prefixes_with_underscores foo_bar d_ritchie # prefixes that include an underscore

    env.db_minsize 1024000 # minimum db size in order to report a specific prefix,

                           # in bytes (defaults to 50M). "0" for none.

    env.mysql_db_dir /var/lib/mysql # default value

=back

=head1 HISTORY

2019-07-25: v 1.0 pcy <pcy.ulyssis.org>: created

=head1 USAGE

Parameters understood:

  config   (required)

  autoconf (optional - used by munin-config)

=head1 MAGIC MARKERS

#%# family=auto

#%# capabilities=autoconf

"""

import os

import re

import sys

def weakbool(x):

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

LIMIT = os.getenv('db_minsize', str(50000 * 1024))

try:

    LIMIT = int(LIMIT)

except ValueError:

    LIMIT = 0

exceptions = os.getenv('prefix_with_underscores', '').split(' ')

if exceptions == ['']:

    exceptions = []

mysqldir = os.getenv('mysql_db_dir', '/var/lib/mysql')

def name_from_path(path):

    filename = os.path.basename(path)

    for name in exceptions:

        if filename.startswith(name):

            return name

    name = filename.split('_')[0]

    def decode_byte(m):

        return bytes.fromhex(m.group(1)).decode('utf-8')

    # Decode MySQL's encoding of non-ascii characters in the table names

    return re.sub('@00([0-9a-z]{2})', decode_byte, name)

def calc_dir_size(directory):

    total = 0

    for filename in os.listdir(directory):

        filedir = os.path.join(directory, filename)

        if os.path.islink(filedir):

            continue

        if os.path.isfile(filedir):

            total += os.path.getsize(filedir)

    return total

def size_per_subdir(parentdir):

    for subdir in os.listdir(parentdir):

        dirpath = os.path.join(parentdir, subdir)

        if os.path.islink(dirpath):

            continue

        if os.path.isdir(dirpath):

            yield calc_dir_size(dirpath), name_from_path(os.path.split(dirpath)[1])

def sizes_by_name(limit=None):

    sizes = {}

    for size, name in size_per_subdir(mysqldir):

        sizes[name] = sizes.get(name, 0) + size

    for name, total_size in sizes.items():

        if limit <= 0 or limit <= total_size:

            yield name, total_size

def fetch():

    for name, total_size in sorted(sizes_by_name(limit=LIMIT), key=lambda x: x[0]):

        print('{}.value {}'.format(name, total_size))

def main():

    if len(sys.argv) == 1:

        fetch()

    elif sys.argv[1] == 'config':

        print('graph_title MySQL disk usage by prefix')

        print('graph_vlabel bytes')

        print('graph_category db')

        names = sorted(name for name, _ in sizes_by_name(limit=LIMIT))

        for name in names:

            print('{0}.label {0}'.format(name))

            print('{}.type GAUGE'.format(name))

            print('{}.draw AREASTACK'.format(name))

    elif sys.argv[1] == 'autoconf':

        print('yes' if os.path.isdir(mysqldir)

              else "no (can't find MySQL's data directory)")

    else:

        fetch()

if __name__ == "__main__":

    main()