check_cpu

#!/bin/sh
################################################################################
# Linux CPU utilization nagios plugin                                          #
# Copyright (c) 2019 Frostbyte <frostbytegr@gmail.com>                         #
#                                                                              #
# Credits:                                                                     #
# <github.com/hugme> - sample code for linux nagios checks                     #
# <devel@nagios-plugins.org> - plugin development guidelines                   #
# <github.com/cyberang3l> - information on the double inclusion of guest times #
#                                                                              #
# 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/>.        #
################################################################################

# Usage helper function
usage() {
cat << EOF
Usage:
$0 [-w util_warn_threshold] [-c util_warn_threshold]
Example: $0 -w 80 -c 90
EOF
exit 3
}

# Input error helper function
inputError() {
	# Throw supplied error message and exit
	echo "$1"
	exit 3
}

# Parse user-supplied arguments
while getopts ":w:c:" inputArgs; do
	case "${inputArgs}" in
		w) thresholdWarn="${OPTARG}" ;;
		c) thresholdCrit="${OPTARG}" ;;
		*) usage ;;
	esac
done
shift $((OPTIND-1))

# Validate any user-supplied arguments
[ -z "$thresholdWarn" ] || {
	[ -z $(echo $thresholdWarn | tr -d [:digit:]) ] || inputError "The warning threshold value may only contain numbers."
	[ $thresholdWarn -le 0 ] || [ $thresholdWarn -ge 100 ] && inputError "The warning threshold value must be between 1 and 99."
}
[ -z "$thresholdCrit" ] || {
	[ -z $(echo $thresholdCrit | tr -d [:digit:]) ] || inputError "The critical threshold value may only contain numbers."
	[ $thresholdCrit -le 0 ] || [ $thresholdCrit -ge 100 ] && inputError "The critical threshold value must be between 1 and 99."
}
[ ! -z "$thresholdWarn" ] && [ ! -z "$thresholdCrit" ] && [ $thresholdCrit -lt $thresholdWarn ] && inputError "The critical threshold value must be higher than or equal to the warning threshold value."

# If the processor statistics file is missing
procStat="/proc/stat"
[ -f "$procStat" ] || {
	# Throw error and exit
	echo "The processor statistics file $procStat is missing."
	exit 3
}

# Disable any non-specified thresholds
[ -z "$thresholdWarn" ] && thresholdWarn=0
[ -z "$thresholdCrit" ] && thresholdCrit=0

# Calculate and construct a standard nagios response
result=$(awk \
	-v thresholdWarn=$thresholdWarn \
	-v thresholdCrit=$thresholdCrit \
	-v initialMeasurement="$(awk '/^cpu\s+/' "$procStat"; sleep 1)" \
	'/^cpu\s+/{
		split(initialMeasurement,initialValues," ")
		for (valueIndex=2; valueIndex<=9 in initialValues; valueIndex++) totalTime-=initialValues[valueIndex]
		for (valueIndex=2; valueIndex<=9; valueIndex++) totalTime+=$valueIndex
		for (valueIndex=2; valueIndex<=NF; valueIndex++) cpuUtil[valueIndex]=100*($valueIndex-initialValues[valueIndex])/totalTime
	}
	END {
		cpuUtil[1]=cpuUtil[2]+cpuUtil[3]+cpuUtil[4]+cpuUtil[7]+cpuUtil[8]
		if (cpuUtil[5] == 0) cpuUtil[1]+=cpuUtil[9]
		result="OK"
		exitCode=0
		if (cpuUtil[1] > thresholdCrit && thresholdCrit > 0) {
			result="CRITICAL"
			exitCode=2
		} else if (cpuUtil[1] > thresholdWarn && thresholdWarn > 0) {
			result="WARNING"
			exitCode=1
		}
		print exitCode" "result" - \
		Utilization: "cpuUtil[1]"% \
		User: "cpuUtil[2]-cpuUtil[10]"% \
		Nice: "cpuUtil[3]-cpuUtil[11]"% \
		System: "cpuUtil[4]"% \
		Idle: "cpuUtil[5]"% \
		IOWait: "cpuUtil[6]"% \
		HWInterrupt: "cpuUtil[7]"% \
		SWInterrupt: "cpuUtil[8]"% \
		Steal: "cpuUtil[9]"% \
		Guest: "cpuUtil[10]"% \
		GuestNice: "cpuUtil[11]"% | \
		util="cpuUtil[1]";"thresholdWarn";"thresholdCrit";0 \
		user="cpuUtil[2]-cpuUtil[10]";0;0;0 \
		nice="cpuUtil[3]-cpuUtil[11]";0;0;0 \
		system="cpuUtil[4]";0;0;0 \
		idle="cpuUtil[5]";0;0;0 \
		iowait="cpuUtil[6]";0;0;0 \
		hwint="cpuUtil[7]";0;0;0 \
		swint="cpuUtil[8]";0;0;0 \
		steal="cpuUtil[9]";0;0;0 \
		guest="cpuUtil[10]";0;0;0 \
		guestnice="cpuUtil[11]";0;0;0"
	}' "$procStat")

# Respond and exit
echo ${result#* }
exit ${result%% *}