Icinga check to get network interface performance data

check_net_if_stats.sh

#!/bin/bash
# Dennis Ullrich
# [email protected]

####################################
############# Variables ##########
################################

# Arrays
declare -A interface
declare -A stats
declare -A unit
declare -A unit_name

# Tmpfile
# WARNING: It will be redeclared while parsing the argument "-i"!
stats[tmpfile]="/tmp/check_net_if_stats.tmp"

# Units for calculation
unit[b]="1"
unit[k]="1000"
unit[m]="1000^2"
unit[g]="1000^3"
unit[t]="1000^4"

# Units for output
unit_name[b]="b"
unit_name[k]="k"
unit_name[m]="m"
unit_name[g]="g"
unit_name[t]="t"


####################################
############# Functions ##########
################################

usage() {
        cat << EOF
Usage: ${0##*/} [-hd] [-i interface] [-u unit]

-h                      Display this help and exit
-d                      Debug mode (be aware - your terminal will be spammed)
-i [interface]          e.g. eth0, lan0, bond0 etc...
-u [unit]               b, k, m, g, t (bit/s (default), kbit/s, mbit/s, gbit/s, tbit/s)
-p [precision]          Number of digits behind dot. Only 0-9 allowed. Default: 0
EOF
        exit 0
}

interface_exists() {
        if ! grep -qm1 "${interface[name]}:" /proc/net/dev; then
                >&2 echo "CRITICAL: Interface \"${interface[name]}\" not found in /proc/net/dev!"
                exit 2
        fi
}

read_stats() {
        stats[new-timestamp]=`date "+%s"`
        stats[new-data]=$(awk "/${interface[name]}/{print \$1,\$2,\$10}" /proc/net/dev)
        newtmp=( ${stats[new-data]} ) 

        stats[old-timestamp]=$(stat -c %Y ${stats[tmpfile]})
        stats[old-data]="$(awk "/${interface[name]}/{print \$1,\$2,\$10}" ${stats[tmpfile]})"
        oldtmp=( ${stats[old-data]} )

        stats[timestamp-diff]=$(( ${stats[new-timestamp]} - ${stats[old-timestamp]} ))

        interface[rx-new]=${newtmp[1]}
        interface[rx-old]=${oldtmp[1]}

        interface[tx-new]=${newtmp[2]}
        interface[tx-old]=${oldtmp[2]}
}

write_stats() {
        cat /proc/net/dev > ${stats[tmpfile]}
}

detect_time_leap() {
        if [ "${stats[timestamp-diff]}" -le 0 ]; then
                >&2 echo "WARNING: Time leap detected! Stats written. Wait for next cycle. |rx_${interface[name]}=0.000${unit_name[${interface[unit]}]};;;;tx_${interface[name]}=0.000${unit_name[${interface[unit]}]};;;;"
                exit 1
        fi
}

detect_if_reset() {
        # if the new counter is smaller than the old counter, we have detected an interface reset
        for x in rx tx; do
                if [ "${interface[$x-new]}" -lt "${interface[$x-old]}" ]; then
                        >&2 echo "WARNING: Interface \"${interface[name]}\" has been resetted! Stats written. Wait for next cycle. |rx_${interface[name]}=0.000${unit_name[${interface[unit]}]};;;;tx_${interface[name]}=0.000${unit_name[${interface[unit]}]};;;;"
                        exit 1
                fi
        done
}

calculate_stats() {
        for x in rx tx; do
                # scale for 0.xxx precision
                # calculate difference between old and new rx * 8 to get it in bit, divide with timestamp diff since last run and divide to target unit
                # check if result is between 0 and 1 and print a 0 since bc does not print a leading zero by default
                interface[$x-sec]=$(bc <<< "scale=${unit[precision]}
                                            result=(( ${interface[$x-new]} - ${interface[$x-old]} ) * 8 ) / ${stats[timestamp-diff]} / ${unit[${interface[unit]}]}
                                            if (0 <= result && result < 1 && result != 0) {
                                                print \"0\"
                                            }
                                            print result;")
        done
}

###############################################
############# Parse, check, set... ##########
###########################################

# Parse args
while getopts “:hdi:u:p:” OPTION; do
    case $OPTION in
        d)          # Debug
                    set -x
            ;;
        h)          usage
            ;;
        i)          interface[name]="$OPTARG"
                    stats[tmpfile]="/tmp/check_net_if_stats_${interface[name]}.tmp"
            ;;
        u)          if [[ ! "$OPTARG" =~ ^[bkmgt]$ ]]; then
                        >&2 echo "Unknown unit $OPTARG in Option $OPTION. Execute script with -h option to get help."; exit 3
                    fi
                    interface[unit]="$OPTARG"
            ;;
        p)          if [[ ! "$OPTARG" =~ ^[0-9]$ ]]; then
                        >&2 echo "Scale \"$OPTARG\" is not between 0 and 9 in Option $OPTION. Execute script with -h option to get help."; exit 3
                    fi
                    unit[precision]=$OPTARG
            ;;
        '?')        >&2 echo "Unknown argument $OPTARG in Option $OPTION. Execute script with -h option to get help."; exit 3
            ;;
    esac
done
# remove the options and optional --
shift "$((OPTIND-1))"

# Set default(s)
[ -z ${interface[unit]} ] && interface[unit]="b"
[ -z ${unit[precision]} ] && unit[precision]=0

# Check input
if [ -z ${interface[name]} ] || [ -z ${interface[unit]} ] || [ -z ${unit[precision]} ]; then
        >&2 echo 'UNKNOWN: Not all required arguments are given. Execute script with -h option to get help.'
        exit 3
fi

###############################
############# MAIN ##########
###########################

if ! type bc > /dev/null 2>&1; then
        echo "UNKNOWN: bc is not installed on this machine!"
        exit 3
fi

interface_exists

if [ ! -f "${stats[tmpfile]}" ]; then
        write_stats
        echo "OK: Stats written. Wait for next cycle."
        exit 0
fi

read_stats
write_stats
detect_time_leap
detect_if_reset
calculate_stats

# output if everything is fine
rx="'rx_${interface[name]}'=${interface[rx-sec]}${unit_name[${interface[unit]}]};0;0;0;0"
tx="'tx_${interface[name]}'=${interface[tx-sec]}${unit_name[${interface[unit]}]};0;0;0;0"
perfdata="${rx} ${tx}"
echo "OK: Interface ${interface[name]} RX: ${interface[rx-sec]} ${unit_name[${interface[unit]}]}/s, TX: ${interface[tx-sec]} ${unit_name[${interface[unit]}]}/s | ${perfdata}"
exit 0