#!/bin/bash
# Nagios check_meminfo script
# 2023 (C) WorldHost Group
# Author: Tsvetan Gerov <tsvetan@wordlhost.group>
# Version 0.2

MEMINFO="/proc/meminfo"

# Default values
MEMWARNING="90"
MEMCRITICAL="95"
SWAPWARNING="70"
SWAPCRITICAL="80"
APPSWARNING="60"
APPSCRITICAL="70"

Help() {
   # Display Help
   echo "check_meminfo"
   echo
   echo "Syntax: check_meminfo [-w|-c|-W|-C]-a|-s|-h"
   echo "options:"
   echo "w     Warning percentage for memory"
   echo "c     Critical percentage for memory".
   echo "W     Warning percentage for swap"
   echo "C     Critical percentage for swap"
   echo "a     Warning percentage for apps"
   echo "s     Critical percentage for apps"
   echo "h     Print this help"
   echo
   exit
}

getMemory() {
    awk '/^MemTotal:/ {total = $2;}
        /^MemFree:/ {free = $2;}
        /^MemAvailable:/ {avail = $2;}
        /^Buffers:/ {buffers = $2;}
        /^Cached:/ {cached = $2;
            if (avail == "") avail = free + buffers + cached;
            printf "%d\n", (total - avail) / total * 100;}' $MEMINFO
}

getSwap() {
    TOTALSWAP=$(grep SwapTotal /proc/meminfo  | awk '{print$2}')
    if [ $TOTALSWAP -eq "0" ]; then
       echo "0"
    else
      awk '/^SwapCached:/ {cached = $2;}
       	  /^SwapTotal:/ {total = $2;}
       	  /^SwapFree:/ {free = $2;
              printf "%d\n", (total - free - cache) / total * 100}' $MEMINFO
    fi
}

getApps() {
    awk '/^MemTotal:/ {total = $2;}
        /^MemFree:/ {free = $2;}
        /^Buffers:/ {buffer = $2;}
        /^Cached:/ {cached = $2;}
        /^Slab:/ {slab = $2;}
        /^PageTables:/ {pagetables = $2;}
        /^SwapCached:/ {swapcache = $2;
            printf "%d\n", (total - free - buffer -cached - slab - pagetables - swapcache) / total * 100}' $MEMINFO
}

while getopts w:c:W:C:a:s:h flag
do
    case "${flag}" in
        w) MEMWARNING=${OPTARG};;
        c) MEMCRITICAL=${OPTARG};;
        W) SWAPWARNING=${OPTARG};;
        C) SWAPCRITICAL=${OPTARG};;
        a) APPSWARNING=${OPTARG};;
        s) APPSCRITICAL=${OPTARG};;
        h) Help;;

    esac
done


# CRITICAL
if [ $(getMemory) -gt $MEMCRITICAL ]; then
    echo "CRITICAL: RAM Usage: $(getMemory)/100%"
    exit 2
elif [ $(getApps) -gt $APPSCRITICAL ]; then
    echo "CRITICAL: Memory APPs Usage: $(getApps)/100%"
    exit 2    
elif [ $(getSwap) -gt $SWAPCRITICAL ]; then
    echo "CRITICAL: SWAP Usage: $(getSwap)/100%"
    exit 2    
# WARNING
elif [ $(getMemory) -gt $MEMWARNING ]; then
    echo "WARNING: RAM Usage: $(getMemory)/100%"
    exit 1
elif [ $(getApps) -gt $APPSWARNING ]; then
    echo "WARNING: Memory APPs: $(getApps)/100%"
    exit 1
elif [ $(getSwap) -gt $SWAPWARNING ]; then
    echo "WARNING: SWAP Usage: $(getSwap)/100%"
    exit 1    
# OK
else
    echo "OK: RAM: $(getMemory)/100%  APPS: $(getApps)/100%  SWAP: $(getSwap)/100%"
    exit 0
fi