#!/bin/sh
# -*- sh -*-
: <<=cut

=head1 NAME

munin_events - Plugin to monitor munin updates

=head1 APPLICABLE SYSTEMS

All systems with "bash", "logtail" and "munin"

=head1 CONFIGURATION

The following is the default configuration

  [munin_events]
  user munin
  env.muninupdate /var/log/munin/munin-update.log
  env.logtail2 /usr/sbin/logtail2

You could trigger alerts on update failures

  [munin_events]
  env.munin_fatal_critical 0
  env.munin_error_critical 0
  env.munin_warning_warning 0
  env.munin_warning_critical 5

=head1 INTERPRETATION

This plugin shows a graph with one line per munin state:
INFO, WARNING, ERROR, FATAL.

=head1 MAGIC MARKERS

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

=head1 VERSION

  1.2.20160514

=head1 AUTHOR

Viktor Szépe <viktor@szepe.net>

=head1 LICENSE

GPLv2

=cut


##############################
# Includes

# shellcheck disable=SC1090
. "$MUNIN_LIBDIR/plugins/plugin.sh"

##############################
# Configurable variables
muninupdate=${muninupdate:-/var/log/munin/munin-update.log}
logtail_bin=${logtail_bin:-/usr/sbin/logtail2}

##############################
# Functions

# Print one value
do_value() {
    FIELD="$1"
    EVENT_LABEL="$2"

    EVENT_COUNT="$("$logtail_bin" -t "$muninupdate" 2> /dev/null | grep -c "^[0-9/: ]\{19\} \[${EVENT_LABEL}\]")"
    if echo "$EVENT_COUNT" | grep -q "[^0-9]"; then
        echo "Cannot determine event count" 1>&2
        exit 10
    fi

    echo "${FIELD}.value ${EVENT_COUNT}"
}

# Print the munin values
values() {
    do_value 'munin_info' 'INFO'
    do_value 'munin_warning' 'WARNING'
    do_value 'munin_error' 'ERROR'
    do_value 'munin_fatal' 'FATAL'
    # Set offset
    "$logtail_bin" "$muninupdate" > /dev/null 1>&2
    chmod 640 "${muninupdate}.offset"
}

# Print the munin config
config() {
    echo 'graph_title Munin update events groupped by log levels'
    echo 'graph_info This graph shows INFO, WARNING, ERROR and FATAL events'
    echo 'graph_category munin'
    echo 'graph_vlabel Number of events'

    echo 'graph_args --base 1000 -l 0'
    echo 'graph_total total'
    echo 'graph_printf %6.0lf'

    echo 'munin_info.label INFO'
    print_warning munin_info
    print_critical munin_info
    echo 'munin_warning.label WARNING'
    print_warning munin_warning
    print_critical munin_warning
    echo 'munin_error.label ERROR'
    print_warning munin_error
    print_critical munin_error
    echo 'munin_fatal.label FATAL'
    print_warning munin_fatal
    print_critical munin_fatal
}

# Print autoconfiguration hint
autoconf() {
    if [ -r "${muninupdate}" ] && [ -x "$logtail_bin" ]; then
        echo "yes"
    else
        echo "missing (${muninupdate} or (${logtail_bin})"
    fi
    exit
}

##############################
# Main

case "$1" in
    config)
        config
        ;;
    autoconf)
        autoconf
        ;;
    *)
        values
        ;;
esac