#!/bin/bash

# This script checks swap space activity on the machine it is run on. It outputs the 
# mumber of bytes moved from physical to swap space in the last DURATION seconds.
#
# Usage: "check_swap_activity -d DURATION(INTEGER) -w WARNING(INTEGER) -c CRITICAL(INTEGER)"
#
# WARNING < CRIT
#
# WARNING and CRIT are measured in bytes
#
# Returns the nagios native status codes:
#
# Nagios Status
#
# 0 = OK (SWAP usage below WARNING) 1 = WARNING (SWAP usage between
# WARNING AND CRITICAL) 2 = CRITICAL (SWAP usage higher than CRITICAL) 3
# = UNKNOWN (Wrong usage)
#
# Tested on:
# - Ubuntu 12.04
#
# Copyright 2012 Shu Wei Tan (webblazers@yahoo.com)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
# 
# Change History:
# 10/05/2012 - Version 1.0 - Shu Wei Tan (webblazers@yahoo.com)
#
## USAGE MESSAGE
usage() { 
cat << EOF
usage: $0 options

This script runs a swap space activity test on the machine.

OPTIONS:
   -h Show this message
   -d Duration in seconds to monitor for swap activity (not optional)
   -w Warning Level (not optional)
   -c Critical Level (not optional)

Warning Level should be lower than Critical Level!

EOF
}

SWAP_WARN=
SWAP_CRIT=
## FETCH ARGUMENTS
while getopts "hd:w:c:" OPTION; do
        case "${OPTION}" in
                h)
                        usage
                        exit 3
                        ;;
		d)
			DURATION=${OPTARG}
			;;
                w)
                        SWAP_WARN=${OPTARG}
                        ;;
                c)
                        SWAP_CRIT=${OPTARG}
                        ;;
                ?)
                        usage
                        exit 3
                        ;;
        esac
done

## CHECK ARGUMENTS
if [ -z ${DURATION} ] ||  [ -z ${SWAP_WARN} ] || [ -z ${SWAP_CRIT} ] || [ ${SWAP_WARN} -gt ${SWAP_CRIT} ] ; then
        usage
        exit 3
fi

## GET SWAP INFO FROM MACHINE
SWAPOUT_ACTIVITY=$(vmstat ${DURATION} 2 | tail -n 1 | awk '{print $8}')

## CHECK SWAPPING ON MACHINE
if [ ${SWAPOUT_ACTIVITY} -lt ${SWAP_WARN} ]; then
	## SWAP IS OK
        LINE="OK! Swapout size in last ${DURATION} second(s): ${SWAPOUT_ACTIVITY} | swapout_size=${SWAPOUT_ACTIVITY}B;${SWAP_WARN};${SWAP_CRIT};"
        echo $LINE
	exit 0
elif [ ${SWAPOUT_ACTIVITY} -gt ${SWAP_WARN} ] && [ ${SWAPOUT_ACTIVITY} -lt ${SWAP_CRIT} ] || [ ${SWAPOUT_ACTIVITY} -eq ${SWAP_WARN} ]; then
	## SWAP IS IN WARNING STATE
        LINE="WARNING! Swapout size in last ${DURATION} second(s): ${SWAPOUT_ACTIVITY} | swapout_size=${SWAPOUT_ACTIVITY}B;${SWAP_WARN};${SWAP_CRIT};"
        echo $LINE
	exit 1
elif [ ${USED_SWAP} -gt ${SWAP_CRIT} ] || [ ${USED_SWAP} -eq ${SWAP_CRIT} ]; then
	## SWAP IS IN CRITICAL STATE
        LINE="CRITICAL! Swapout size in last ${DURATION} second(s): ${SWAPOUT_ACTIVITY} | swapout_size=${SWAPOUT_ACTIVITY}B;${SWAP_WARN};${SWAP_CRIT};"
        echo $LINE
        exit 2
else

	## SHOULD NEVER REACH THIS POINT, MUST BE USAGE :)
        usage
        exit 3
fi