#!/usr/bin/env python3

"""Munin plugin to monitor keepalived state and status.

=head1 NAME

keepalived - monitor keepalived state and status

=head1 APPLICABLE SYSTEMS

Linux systems with keepalived running.

=head1 CONFIGURATION

Pidfile and datafile locations must be configured if following default
values are not correct:

    [keepalived]
    user root
    env.pidfile /run/keepalived.pid
    env.datafile /run/keepalived/keepalived.data

=head1 AUTHOR

Kim B. Heino <b@bbbs.net>

=head1 LICENSE

GPLv2

=head1 MAGIC MARKERS

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

=cut
"""

import os
import pathlib
import sys
import time
import unicodedata


PIDFILE = pathlib.Path(os.getenv('pidfile', '/run/keepalived.pid'))
DATAFILE = pathlib.Path(os.getenv('datafile',
                                  '/run/keepalived/keepalived.data'))


def safename(name):
    """Return safe variable name."""
    # Convert ä->a as isalpha('ä') is true
    value = unicodedata.normalize('NFKD', name)
    value = value.encode('ASCII', 'ignore').decode('utf-8')

    # Remove non-alphanumeric chars
    return ''.join(char.lower() if char.isalnum() else '_' for char in value)


def datafile_fresh(fresh_time):
    """Check if datafile exists and is fresh."""
    try:
        stat = DATAFILE.stat()
        if stat.st_mtime > fresh_time and stat.st_size > 1024:
            return True
    except FileNotFoundError:
        pass
    return False


def update_datafile():
    """Signal keepalived to write data file."""
    # Find keepalived's pid
    try:
        pid = int(PIDFILE.read_text('utf-8'))
    except (FileNotFoundError, ValueError):
        return False

    # Check if current file is fresh
    fresh = time.time() - 30
    if datafile_fresh(fresh):
        return True

    # Signal keepalived to update file
    try:
        os.kill(pid, 10)  # keepalived --signum=DATA
    except OSError:
        return False

    # Wait for datafile to be updated
    for _dummy_wait in range(15):
        if datafile_fresh(fresh):
            time.sleep(1)  # One extra second to make it sure it's complete
            return True
        time.sleep(1)
    return False


def read_datafile():
    """Update, read and parse datafile."""
    if not update_datafile():
        return None
    data = {
        'vrrp_instance': {},
        'vrrp_sync_group': {},
    }
    section = None
    vrrp_instance = None
    for line in DATAFILE.read_text('utf-8').splitlines():
        if line.startswith('------<'):
            section = line.split('< ', 1)[1].split(' >')[0]
        elif ' = ' in line:
            key, value = line.split(' = ', 1)
            # Global
            if section == 'Global definitions' and key == ' Router ID':
                data['router_id'] = value

            # Instance
            elif section == 'VRRP Topology' and key == ' VRRP Instance':
                vrrp_instance = value
            elif section == 'VRRP Topology' and key == '   State':
                data['vrrp_instance'][vrrp_instance] = value

            # Sync group
            elif section == 'VRRP Sync groups' and key == ' VRRP Sync Group':
                name, state = value.split(', ', 1)
                data['vrrp_sync_group'][name] = state

    return data if 'router_id' in data else None


def state_as_number(value):
    """Return state as number."""
    if value == 'MASTER':
        return 1
    if value == 'BACKUP':
        return 0
    return -1  # FAILED


def config():
    """Print plugin config."""
    data = read_datafile()
    if not data:
        return

    print('multigraph keepalived_state')
    print('graph_title Keepalived VRRP state')
    print('graph_info VRRP states: 1 = master, 0 = backup, -1 = failed')
    print('graph_category network')
    print('graph_vlabel state')
    print('graph_args --lower-limit -1 --upper-limit 1')
    print('graph_scale no')
    for key in data['vrrp_sync_group']:
        print(f'sg_{safename(key)}.label Sync group {key} state')
        print(f'sg_{safename(key)}.warning 0:1')
    for key in data['vrrp_instance']:
        print(f'i_{safename(key)}.label Instance {key} state')
        print(f'i_{safename(key)}.warning 0:1')

    if os.environ.get('MUNIN_CAP_DIRTYCONFIG') == '1':
        fetch(data)


def fetch(data=None):
    """Print values."""
    if not data:
        data = read_datafile()
        if not data:
            return

    print('multigraph keepalived_state')
    for key, value in data['vrrp_sync_group'].items():
        print(f'sg_{safename(key)}.value {state_as_number(value)}')
    for key, value in data['vrrp_instance'].items():
        print(f'i_{safename(key)}.value {state_as_number(value)}')


if __name__ == '__main__':
    if len(sys.argv) > 1 and sys.argv[1] == 'autoconf':
        print('yes' if read_datafile() else 'no (no keepalived running)')
    elif len(sys.argv) > 1 and sys.argv[1] == 'config':
        config()
    else:
        fetch()