#!/bin/bash

###############################################################################
# The MIT License (MIT)                                                        #
#                                                                              #
# Copyright (c) 2016 Achim Christ                                              #
#                                                                              #
# Permission is hereby granted, free of charge, to any person obtaining a copy #
# of this software and associated documentation files (the "Software"), to deal#
# in the Software without restriction, including without limitation the rights #
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell    #
# copies of the Software, and to permit persons to whom the Software is        #
# furnished to do so, subject to the following conditions:                     #
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# The above copyright notice and this permission notice shall be included in   #
# all copies or substantial portions of the Software.                          #
#                                                                              #
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR   #
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,     #
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  #
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER       #
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,#
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE#
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################################################################################

# Name:               Check OpenVZ Memory
# Author:             Achim Christ - achim(dot)christ(at)gmail(dot)com
# Version:            1.2
# Dependencies:       bc - An arbitrary precision calculator language
# Website:            https://github.com/acch/nagios-plugins

# OpenVZ Linux containers have a notion of 'guaranteed memory' which is typically lower than the total amount of memory available.
# Since memory is shared among containers, allocating more than the guaranteed amount may eventually fail. This typically results in transient errors which are extremely hard to identify.
# This bash script reports on and checks memory usage of an OpenVZ container, and warns if it exceeds the amount of guaranteed memory.
# The plugin produces Nagios performance data so it can be graphed.

# Additional detail on the monitored parameters can be found here:
#   http://wiki.openvz.org/UBC_primary_parameters#vmguarpages

# The actual code is managed in the following GitHub rebository - please use the Issue Tracker to ask questions, report problems or request enhancements.
#   https://github.com/acch/nagios-plugins

# Disclaimer: This sample is provided 'as is', without any warranty or support. It is provided solely for demonstrative purposes - the end user must test and modify this sample to suit his or her particular environment. This code is provided for your convenience, only - though being tested, there's no guarantee that it doesn't seriously break things in your environment! If you decide to run it, you do so on your own risk!

# Version History:
# 1.0    4.2.2016     Initial Release
# 1.1    10.2.2016    Added check for dependencies
# 1.2    14.2.2016    Added check for user_beancounters

# Check for dependencies
if [ ! -x /usr/bin/bc ]
then
  echo "'bc' not found - please install it!"
  exit 3
fi

# Check for user_beancounters
if [ ! -e /proc/user_beancounters ]
then
  echo "'/proc/user_beancounters' not found - is this a OpenVZ container?"
  exit 3
fi
if [ ! -r /proc/user_beancounters ]
then
  echo "'/proc/user_beancounters' not readable - root privileges required!"
  exit 3
fi

# Read memory information from Kernel
mem_actual=$(grep privvmpages /proc/user_beancounters | awk '{print $3}')
mem_warn=$(grep vmguarpages /proc/user_beancounters | awk '{print $4}')
mem_crit=$(grep privvmpages /proc/user_beancounters | awk '{print $4}')
mem_max=$(grep privvmpages /proc/user_beancounters | awk '{print $5}')

# Check for errors
if [ "$mem_actual" -gt "$mem_crit" ]
then
  # Memory above critical threshold
  retcode=2
  msg="CRITICAL"
# Check for warnings
elif [ "$mem_actual" -gt "$mem_warn" ]
then
  # Memory above warning threshold
  retcode=1
  msg="WARNING"
# Everything's fine
else
  # Memory below thresholds
  retcode=0
  msg="OK"
fi

# Compute 'performance' data
mem_actual_mb=$(echo "scale=3; $mem_actual/250" | bc)
mem_warn_mb=$(echo "scale=3; $mem_warn/250" | bc)
mem_crit_mb=$(echo "scale=3; $mem_crit/250" | bc)
mem_max_mb=$(echo "scale=3; $mem_max/250" | bc)

# Produce Nagios output
echo "MEMORY $msg - ${mem_actual_mb}MB used currently | memused=${mem_actual_mb}MB;${mem_warn_mb};${mem_crit_mb};0;${mem_max_mb}"
exit $retcode