#!/bin/sh
# -*- sh -*-

set -eu

: <<=cut

=head1 NAME

zpool_iostat - Plugin to monitor transfer statistics of ZFS pools

=head1 APPLICABLE SYSTEMS

All systems with "zpool" installed.

=head1 CONFIGURATION

No configuration is required.

=head1 INTERPRETATION

This plugin shows a graph with read (positive) and write (negative) values
for the IO transfer of each pool.

=head1 MAGIC MARKERS

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

=head1 AUTHOR

tsaavik <github@hellspark.com>
Peter Doherty <peterd@acranox.org>
Lars Kruse <devel@sumpfralle.de>

=head1 LICENSE

GPLv2

=cut


# shellcheck source=/usr/share/munin/plugins/plugin.sh
. "$MUNIN_LIBDIR/plugins/plugin.sh"


ZPOOL_BIN=/sbin/zpool
ACTION="${1:-}"


if [ "$ACTION" = "autoconf" ]; then
	if [ -x "$ZPOOL_BIN" ]; then
		echo yes
	else
		echo "no (missing executable '$ZPOOL_BIN')"
	fi
	exit 0
fi

zlines=$("$ZPOOL_BIN" iostat -v | wc -l | sed 's/ //g')
pool_iostat=$("$ZPOOL_BIN" iostat -v 1 1 | tail "-$zlines")
zlist=$(echo "$pool_iostat" | gawk '/alloc/ {next}; /avail/ {next}; /raid/ {next}; /mirror/ {next}; { if ( $4 >=0 ) print $1}' | tr ' ' '\n')

# parse the n'th column of the iostat output for a given pool as a number (interpreting K and M suffixes)
get_pool_iostat() {
	local pool_label="$1"
	local stat_column="$2"
	echo "$pool_iostat" \
		| gawk '{ if ($1 == "'"$pool_label"'") print $'"$stat_column"'; }' \
		| gawk '/M/ {print strtonum($1)*1000}; /K/ {print strtonum($1)}; /[0-9]$/ {print int($1)/1000}'
}

if [ "$ACTION" = "config" ]; then
        echo 'graph_title zpool iostat'
        echo 'graph_args --base 1000 -l 0'
        echo 'graph_vlabel write - read KBytes/s'
        echo 'graph_category disk'
        echo 'graph_scale no'
        echo 'graph_info This graph shows zpool iostat'
	# assemble the "graph_order" as a sorted list of read/write pairs for each poll
	printf "graph_order"
	echo "$zlist" | while read -r pool_id; do
		fieldname="$(clean_fieldname "pool_$pool_id")"
		printf " %s_read %s_write" "$fieldname" "$fieldname"
	done
	# finalize the 'graph_order'
	echo
	# output all fields: write as negative numbers and read as positive
	echo "$zlist" | while read -r pool_id; do
		fieldname="$(clean_fieldname "pool_$pool_id")"
		echo "${fieldname}_read.label $pool_id"
		echo "${fieldname}_read.type GAUGE"
		echo "${fieldname}_read.graph no"
		echo "${fieldname}_write.label $pool_id"
		echo "${fieldname}_write.type GAUGE"
		echo "${fieldname}_write.negative ${fieldname}_read"
        done
        exit 0
fi
echo "$zlist" | while read -r pool_id; do
	fieldname="$(clean_fieldname "pool_$pool_id")"
	echo "${fieldname}_read.value $(get_pool_iostat "$pool_id" 6)"
	echo "${fieldname}_write.value $(get_pool_iostat "$pool_id" 7)"
done