#!/bin/bash

iostat=`which iostat 2>/dev/null`
bc=`which bc 2>/dev/null`

function help {
echo -e "\n\tThis plugin shows the I/O usage of the specified disk, using the iostat external program.\n\tIt prints three statistics: Transactions per second (tps), Kilobytes per second\n\tread from the disk (KB_read/s) and and written to the disk (KB_written/s)\n\n$0:\n\t-c <tps>,<read>,<wrtn>\tSets the CRITICAL level for tps, KB_read/s and KB_written/s, respectively\n\t-w <tps>,<read>,<wrtn>\tSets the WARNING level for tps, KB_read/s and KB_written/s, respectively\n"
        exit -1
}

# Ensuring we have the needed tools:
( [ ! -f $iostat ] || [ ! -f $bc ] ) && \
        ( echo "ERROR: You must have iostat and bc installed in order to run this plugin" && exit -1 )

# Getting parameters:
while getopts "d:w:c:h" OPT; do
        case $OPT in
                "w") warning=$OPTARG;;
                "c") critical=$OPTARG;;
                "h") help;;
        esac
done

# Adjusting the three warn and crit levels:
crit_tps=`echo $critical | cut -d, -f1`
crit_read=`echo $critical | cut -d, -f2`
crit_written=`echo $critical | cut -d, -f3`

warn_tps=`echo $warning | cut -d, -f1`
warn_read=`echo $warning | cut -d, -f2`
warn_written=`echo $warning | cut -d, -f3`

# Checking parameters:
( [ "$warn_tps" == "" ] || [ "$warn_read" == "" ] || [ "$warn_written" == "" ] || \
  [ "$crit_tps" == "" ] || [ "$crit_read" == "" ] || [ "$crit_written" == "" ] ) &&
                echo "ERROR: You must specify all warning and critical levels" && help

( [[ "$warn_tps" -ge  "$crit_tps" ]] || \
  [[ "$warn_read" -ge  "$crit_read" ]] || \
  [[ "$warn_written" -ge  "$crit_written" ]] ) && \
  echo "ERROR: critical levels must be highter than warning levels" && help

tps=0
kbread=0
kbwritten=0

stats=`iostat -d -k | tail -n +4 | head -n -1`
while read line; do

        stat=$line
        # Doing the actual check:
        d_tps=`echo $stat | awk '{printf "%f", $2}'`
        d_kbread=`echo $stat | awk '{printf "%f", $3}'`
        d_kbwritten=`echo $stat | awk '{printf "%f", $4}'`

        if [ -n "$d_tps" ]; then 
                tps=`echo "$d_tps + $tps" | bc | awk '{printf "%f", $0}'`
                kbread=`echo "$d_kbread + $kbread" | bc | awk '{printf "%f", $0}'`
                kbwritten=`echo "$d_kbwritten + $kbwritten" | bc | awk '{printf "%f", $0}'`
        fi

done <<< "$stats"

# Comparing the result and setting the correct level:
if ( [ "`echo "$tps >= $crit_tps" | bc`" == "1" ] || [ "`echo "$kbread >= $crit_read" | bc`" == "1" ] || \
     [ "`echo "$kbwritten >= $crit_written" | bc`" == "1" ] ); then
        msg="CRITICAL"
        status=2
else if ( [ "`echo "$tps >= $warn_tps" | bc`" == "1" ] || [ "`echo "$kbread >= $warn_read" | bc`" == "1" ] || \
          [ "`echo "$kbwritten >= $warn_written" | bc`" == "1" ] ); then
                msg="WARNING"
                status=1
     else
        msg="OK"
        status=0
     fi
fi

# Printing the results:
echo "$msg - I/O stats tps=$tps KB_read/s=$kbread KB_written/s=$kbwritten | 'tps'=$tps; 'KB_read/s'=$kbread; 'KB_written/s'=$kbwritten;"

exit $status