#!/bin/bash
# ======================================================================
#
# Check RAM usage
#
# requirements:
# - bc
#
# DOC: https://access.redhat.com/solutions/406773 
# explains /proc/meminfo
#
# SYNTAX:
# check_memory [-w [int] -c [int] -s [int]]
#   -w  Warning level for RAM usage [%]; default: 75
#   -c  Critical level for RAM usage; default: 90
#   -s  Critical level for SWAP usage; default: 5
#
# ----------------------------------------------------------------------
# 2020-03-16  v1.0  <axel.hahn@iml.unibe.ch>
# 2020-03-25  v1.1  <axel.hahn@iml.unibe.ch>  added slab; fix usage based on MemAvailable
# 2020-04-28  v1.2  <axel.hahn@iml.unibe.ch>  allow small swap usage before critical; update output RAM + Swap usage
# 2020-07-08  v1.3  <axel.hahn@iml.unibe.ch> FIX: set "ph." instead "ps."
# 2020-07-16  v1.4  <axel.hahn@iml.unibe.ch> FIX: add unit MB in the performance data (see #3939)
# ======================================================================


. `dirname $0`/inc_pluginfunctions


# ----------------------------------------------------------------------
# FUNCTIONS
# ----------------------------------------------------------------------

# get a memory status value
# /proc/meminfo conatains values in kB - it is divided by 1024
# --> return values are MB
function getMemvalue(){
    echo `grep "^$1:" /proc/meminfo | awk '{ print $2 }' ` / 1024 | bc
}

# ----------------------------------------------------------------------
# MAIN
# ----------------------------------------------------------------------

# --- check required tools
ph.reqire bc

# --- check param -h
if [ "$1" = "-h" ]; then
    echo "
    usage: $0 [ -w value -c value -h ]

        -w  Warning level for RAM usage [%]; default: 75
        -c  Critical level for RAM usage; default: 90
        -s  Critical level for SWAP usage; default: 5
        -h  this help
    "
    exit 0
fi

# set default / override from command line params
typeset -i iWarnLimit=`     ph.getValueWithParam 75 w "$@"`
typeset -i iCriticalLimit=` ph.getValueWithParam 90 c "$@"`
typeset -i iCriticalSwap=`  ph.getValueWithParam 5  s "$@"`

# --- RAM
typeset -i ramTotal=`    getMemvalue MemTotal`
typeset -i ramAvail=`    getMemvalue MemAvailable`
typeset -i ramUsed=$ramTotal-$ramAvail

typeset -i ramFree=`     getMemvalue MemFree`
typeset -i ramBuffers=`  getMemvalue Buffers`
typeset -i ramCached=`   getMemvalue Cached`
typeset -i ramSReclaim=` getMemvalue SReclaimable`

typeset -i ramUsage=`echo "($ramUsed) *100 / $ramTotal " | bc`

# --- Swap
typeset -i swapTotal=`   getMemvalue SwapTotal`
typeset -i swapFree=`    getMemvalue SwapFree`
typeset -i swapCached=`  getMemvalue SwapCached`

typeset -i swapUsage=0
if [ $swapTotal -gt 0 ]; then
    swapUsage=`echo "($swapCached)*100 / $swapTotal " | bc`
fi


# --- set status
ph.setStatusByLimit $ramUsage $iWarnLimit $iCriticalLimit
# if [ $swapCached -gt 0 ]; then
if [ $swapUsage -ge $iCriticalSwap ]; then
    ph.setStatus "critical"
fi

if [ $swapTotal -gt 0 ]; then
    ph.status "RAM usage $ramUsage % of $ramTotal MB .. SWAP usage $swapCached MB = $swapUsage % of $swapTotal MB total"
else
    ph.status "RAM usage $ramUsage % of $ramTotal MB (machine has no Swap)"
fi

# --- show details
echo
cat /proc/meminfo | egrep "^(Mem|Cache|Buffers|Swap|Slab|SReclaimable)"


# --- performance data
ph.perfadd "memory-total"    "${ramTotal}MB"    "" "" 0 ${ramTotal}
ph.perfadd "memory-used"     "${ramUsed}MB"     "" "" 0 ${ramTotal}
ph.perfadd "memory-avail"    "${ramAvail}MB"    "" "" 0 ${ramTotal}

ph.perfadd "memory-free"     "${ramFree}MB"     "" "" 0 ${ramTotal}
ph.perfadd "memory-buffers"  "${ramBuffers}MB"  "" "" 0 ${ramTotal}
ph.perfadd "memory-cached"   "${ramCached}MB"   "" "" 0 ${ramTotal}
ph.perfadd "memory-sreclaim" "${ramSReclaim}MB" "" "" 0 ${ramTotal}

# add swap performance data only if swap is available
if [ $swapTotal -gt 0 ]; then
    ph.perfadd "swap-total"      "${swapTotal}MB"   "" "" 0 ${swapTotal}
    ph.perfadd "swap-free"       "${swapFree}MB"    "" "" 0 ${swapTotal}
    ph.perfadd "swap-cached"     "${swapCached}MB"  "" "" 0 ${swapTotal}
fi

ph.exit

# ----------------------------------------------------------------------