#!/usr/bin/env python3


"""
=pod

=head1 NAME

btrfs_device_usage - Script to monitor usage of btrfs devices

=head1 CONFIGURATION

Simply create a symlink in your plugins directory like with any other plugin.
Must be run as root.

[btrfs_device_usage]
user root

You can optionaly configure the warning and critical limits for byte and
percentage graphs. By default percent_warning is set to 95 and percent_critical
is 98. For the byte-graphs there are no default limits set. You can set the
limits either for the entire graph (byte_ percent_) or per individual filesystem
using it's UUID (replace minus with underscore). The individual values take
precedence over the general ones. See the following example:

btrfs_device_usage]
user root
env.byte_warning 400300200100
env.percent_critical 97
env.percent_10164f3f_6670_4982_a941_bffb50d27f29_warning 23
env.byte_10164f3f_6670_4982_a941_bffb50d27f29_critical 5000000000

=head2 DEFAULT CONFIGURATION

=head1 BUGS

=head1 AUTHOR

2019-2021, HaseHarald

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=head1 LICENSE

LGPLv3

=cut
"""


# This file contains a munin-plugin to gather btrfs statistics per device.
#
# This is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this plugin.  If not, see <http://www.gnu.org/licenses/>.


import btrfs
import os
import sys


def munin_config(fs):
    fsid = str(fs.fsid).replace('-', '_')

    byte_warning = os.getenv('byte_warning', default=False)
    byte_critical = os.getenv('byte_critical', default=False)
    byte_warning = os.getenv('byte_' + fsid + '_warning',
                             default=byte_warning)
    byte_critical = os.getenv('byte_' + fsid + '_critical',
                              default=byte_critical)

    percent_warning = os.getenv('percent_warning', default=95)
    percent_critical = os.getenv('percent_critical', default=98)
    percent_warning = os.getenv('percent_' + fsid + '_warning',
                                default=percent_warning)
    percent_critical = os.getenv('percent_' + fsid + '_critical',
                                 default=percent_critical)

    print("multigraph btrfs_device_usage_byte_" + fsid)
    print("graph_title btrfs usage by device in bytes on " + fs.path)
    print("graph_args --base 1024 -l 0")
    print("graph_scale yes")
    print("graph_vlabel bytes")
    print("graph_category disk")
    print("graph_info This graph shows bytes used by btrfs on every device")

    devices = fs.devices()
    for this_device in devices:
        this_dev_info = fs.dev_info(this_device.devid)
        this_dev_name = this_dev_info.path.replace('/dev/', '')
        print("btrfs_bytes_" + fsid + "_" + str(this_device.devid) +
              ".label " + this_dev_name)
        if byte_warning:
            print("btrfs_bytes_" + fsid + "_" + str(this_device.devid) +
                  ".warning " + str(byte_warning))
        if byte_critical:
            print("btrfs_bytes_" + fsid + "_" + str(this_device.devid) +
                  ".critical " + str(byte_critical))

    print("")

    print("multigraph btrfs_device_usage_percent_" + fsid)
    print("graph_title btrfs usage by device in percent on " + fs.path)
    print("graph_args --base 1000 -l 0")
    print("graph_scale no")
    print("graph_vlabel %")
    print("graph_category disk")
    print("graph_info This graph shows percentage used by btrfs on every \
          device. Maesured in percentage of device capacity.")

    devices = fs.devices()
    for this_device in devices:
        this_dev_info = fs.dev_info(this_device.devid)
        this_dev_name = this_dev_info.path.replace('/dev/', '')
        print("btrfs_percent_" + fsid + "_" + str(this_device.devid) +
              ".label " + this_dev_name)
        print("btrfs_percent_" + fsid + "_" + str(this_device.devid) +
              ".warning " + str(percent_warning))
        print("btrfs_percent_" + fsid + "_" + str(this_device.devid) +
              ".critical " + str(percent_critical))

    print("")


def munin_values(fs):
    fsid = str(fs.fsid).replace('-', '_')
    devices = fs.devices()

    print("multigraph btrfs_device_usage_byte_" + fsid)

    for this_device in devices:
        this_dev_info = fs.dev_info(this_device.devid)
        print("btrfs_bytes_" + fsid + "_" + str(this_device.devid) +
              ".value " + str(this_dev_info.bytes_used))

    print("")

    # Reset device iterator
    devices = fs.devices()

    print("multigraph btrfs_device_usage_percent_" + fsid)

    for this_device in devices:
        this_dev_info = fs.dev_info(this_device.devid)
        usage = 100.0 * this_dev_info.bytes_used / this_dev_info.total_bytes
        print("btrfs_percent_" + fsid + "_" + str(this_device.devid) +
              ".value " + str(round(usage, 2)))

    print("")


def main():
    for path in btrfs.utils.mounted_filesystem_paths():
        with btrfs.FileSystem(path) as fs:
            if len(sys.argv) > 1 and sys.argv[1] == "config":
                munin_config(fs)
            else:
                munin_values(fs)


if __name__ == "__main__":
    main()

exit(0)