Munin contributed plugins

#!/bin/sh

# shellcheck shell=dash

# -*- sh -*-

: << =cut

=head1 NAME

whois_ - Plugin to monitor expiry dates of domain in the WHOIS database

Though the plugin will be called every 5 minutes, it will keep a cache, and

only query the WHOIS database every hour.

=head1 CONFIGURATION

None is needed, just

	ln -s /path/to/whois_ whois_domain.tld

in Munin's installed plugins directory will suffice to start monitoring

C<domain.tld>.

However, a few parameters, all optional, can be set if needed

	[whois_domain.tld]

	env.extract_re s/PATTERN/REPL/

	env.warning_days <default: 7 days>

	env.critical_days <default: 3 days>

	env.cache_expiry_mins <default: 60 minutes>

The C<extract_re> will be used in C<sed> to extract the relevant expiry date. It

default to C<s/^.*[Ee]xpir.*: //>. Only lines for which a replacement has

happened will be considered, and the pattern should take care to only output

one line. While the default RegExp just finds a leader pattern and removes it,

it is possible to write more complex logic to format the date. The extracted

date needs to be in a format supported by C<date(1)>'s C<--date> parameter.

=head1 AUTHOR

Olivier Mehani

Copyright (C) 2020 Olivier Mehani <shtrom+munin@ssji.net>

=head1 LICENSE

SPDX-License-Identifier: GPL-3.0-or-later

=head1 MAGIC MARKERS

 #%# family=manual

=cut

set -eu

# shellcheck disable=SC1090

. "${MUNIN_LIBDIR}/plugins/plugin.sh"

if [ "${MUNIN_DEBUG:-0}" = 1 ]; then

	set -x

fi

EXTRACT_RE=${extract_re:-'s/^.*[Ee]xpir.*: //'}

WARNING=${warning_days:-7}

CRITICAL=${critical_days:-3}

CACHE_EXPIRY=${cache_expiry_mins:-60}

# Args: domain name (optional, for title)

graph_config() {

	NAMETITLE=${1:+ for ${1}}

	cat << EOF

graph_title Domain registration expiry${NAMETITLE}

graph_category network

graph_vlabel days

EOF

}

# Args: domain name

# Separated from graph_config so we can easily extend the plugin to support multiple domains.

config() {

	local NAME=${1}

	local FIELDNAME

	FIELDNAME="$(clean_fieldname "${NAME}")"

	cat << EOF

${FIELDNAME}.label expiry

${FIELDNAME}.cdef ${FIELDNAME},86400,/

${FIELDNAME}.warning ${WARNING}:

${FIELDNAME}.critical ${CRITICAL}:

EOF

}

# Args: domain name

fetch() {

	local NAME=${1}

	local FIELDNAME

	local CACHEFILE

	FIELDNAME="$(clean_fieldname "${NAME}")"

	CACHEFILE="${MUNIN_PLUGSTATE}/$(basename "${0}").${FIELDNAME}.cache"

	if [ -z "$(find "${CACHEFILE}" -mmin -"${CACHE_EXPIRY}" 2>/dev/null)" ]; then

		EXPIRY="$(whois "${NAME}" 2>/dev/null | sed -n "${EXTRACT_RE}p;T;q")" # T;q exits after printing the first match

		DELTA_TS=U

		if [ -n "${EXPIRY}" ]; then

			EXPIRY_TS="$(date +%s -d "${EXPIRY}")"

			NOW_TS="$(date +%s)"

			DELTA_TS=$((EXPIRY_TS-NOW_TS))

		fi

		echo "${FIELDNAME}.value ${DELTA_TS}" > "${CACHEFILE}"

	fi

	cat "${CACHEFILE}"

}

main() {

	local MODE="${1:-}"

	local NAME

	NAME="$(echo "${0}" | sed 's/.*_//')"

	case "${MODE}" in

		'config')

			graph_config "${NAME}"

			config "${NAME}"

			;;

		*)

			fetch "${NAME}"

			;;

	esac

}

main "$@"