How to check all the sensors (a Nagios plugin)

28th November 201516th July 2016 Vladimir Melnik

Ever fancied a Nagios plugin to check all the sensors on the host without any hassle? Try this one, it collects all the sensors’ input values, compares it to their thresholds (the script collects threshold values from the system by itself). Then the plugin throws a warning when the rate of input value to the threshold value is 0.8 or more (actually you can change it by the -w option), also it yells about the critical state if the rate is equal or greater than 1 (of course, you can change it too by the -c option, although I wouldn’t suggest you to do that).

Oh, I almost forgot to add: you need to have lm_sensors utiluity installed.

#!/bin/bash

CODE_OK=0
CODE_UNKNOWN=1
CODE_WARNING=2
CODE_CRITICAL=3

WARNING_THRESHOLD="80%"
CRITICAL_THRESHOLD="100%"
DEBUG=0

while getopts ":C:S:c:w:dh" OPT; do
    case "${OPT}" in
        C)
            CHIP="${OPTARG}"
            ;;
        S)
            SENSORS="${OPTARG}"
            ;;
        c)
            CRITICAL_THRESHOLD="${OPTARG}"
            ;;
        w)
            WARNING_THRESHOLD="${OPTARG}"
            ;;
        d)
            DEBUG=1
            ;;
        h)
            cat <<__USAGE_END__
$0 [-C <chip>] [-S <sensors>] [-w <warn>] [-c <crit>] [-d] [-h]

    -C <chip>     - to read sensors on certain chip
    -S <sensors>  - to read sensors matching certain regexp
    -w <warning>  - warning rate threshold (80% by default)
    -c <critical> - critical rate threshild (100% by default)
    -d            - to print debug info
    -h            - you've just done it :)
__USAGE_END__
                >&2
            exit ${CODE_UNKNOWN}
            ;;
        \?)
            echo "Invalid option: -${OPTARG}, see -h" >&2
            exit ${CODE_UNKNOWN}
            ;;
        :)
            echo "Option -${OPTARG} requires some argument, see -h" >&2
            exit ${CODE_UNKNOWN}
            ;;
    esac
done

if [ -z "${CHIP}" ]; then
    DATA=$(/bin/sensors -u)
else
    DATA=$(/bin/sensors -u "${CHIP}")
fi
if [ $? -ne 0 ]; then
    echo "Can't get sensors' data" >&2
    exit ${CODE_UNKNOWN}
fi

echo "${DATA}" | awk \
    -v CriticalT="${CRITICAL_THRESHOLD}" \
    -v WarningT="${WARNING_THRESHOLD}" \
    -v Sensors="${SENSORS}" \
    -v CodeOK="${CODE_OK}" \
    -v CodeUnknown="${CODE_UNKNOWN}" \
    -v CodeWarning="${CODE_WARNING}" \
    -v CodeCritical="${CODE_CRITICAL}" \
    -v Debug=${DEBUG} \
    '
function Croak(Sensor, Input, Threshold) {
    printf(\
        "%s sensor shows %0.3f whilst its threshold is %0.3f (%0.0f%)\n", \
        Sensor, Input, Threshold, Input / Threshold * 100 \
    )
}
function Finish(Sensor, Input, Threshold, Alarm) {
    if(Debug) {
        printf( \
            "Finishing the %s sensor: input is %0.3f threshold is %0.3f alarm flag is %0.3f\n", \
            Sensor, Input, Threshold, Alarm \
        )
    }
    if(length(Sensors)) {
        if(Sensor !~ Sensors) {
            return
        }
    }
    if(Alarm > 0) {
        printf("%s sensor in alarm state\n", Sensor)
        exit CodeCritical
    }
    if(match(CriticalT, /^([[:digit:]]+)%$/, matched)) {
        if ((length(Threshold) > 0) && (Input / Threshold * 100 >= matched[1])) {
            Croak(Sensor, Input, Threshold)
            exit CodeCritical
        }
    } else {
        if (Input >= CriticalT) {
            Croak(Sensor, Input, CriticalT)
            exit CodeCritical
        }
    }
    if(match(WarningT, /^([[:digit:]]+)%$/, matched)) {
        if ((length(Threshold) > 0) && (Input / Threshold * 100 >= matched[1])) {
            Croak(Sensor, Input, Threshold)
            exit CodeWarning
        }
    } else {
        if (Input >= WarningT) {
            Croak(Sensor, Input, WarningT)
            exit CodeWarning
        }
    }
}
// {
    if(match($0, /^([^:]+):$/, matched)) {
        SensorNew = matched[1]
        if(length(Sensor) > 0) {
            Finish(Sensor, Input, Threshold, Alarm)
        }
        Sensor = SensorNew
        Input = ""
        Threshold = ""
        Alarm = ""
    }
    if(match($0, /^[[:space:]]+([^:]+): ([0-9\.\-]+)$/, matched)) {
        Parameter = matched[1]
        Value = matched[2]
        if(Parameter ~ /_input$/) {
            Input = Value
        }
        if(Parameter ~ /_(max|crit|emergency)$/) {
            if (Value > Threshold) {
                Threshold = Value
            }
        }
        if(Parameter ~ /_alarm$/) {
            Alarm = Value
        }
    }
}
END {
    if(length(Sensor) > 0) {
        Finish(Sensor, Input, Threshold, Alarm)
    }
}'

STATUS="${?}"
if [ "${STATUS}" -lt 4 ]; then
    exit "${STATUS}"
else
    exit "${CODE_UNKNOWN}"
fi

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#!/bin/bash

CODE_OK=0

CODE_UNKNOWN=1

CODE_WARNING=2

CODE_CRITICAL=3

WARNING_THRESHOLD="80%"

CRITICAL_THRESHOLD="100%"

DEBUG=0

while getopts ":C:S:c:w:dh" OPT; do

case "${OPT}" in

CHIP="${OPTARG}"

;;

SENSORS="${OPTARG}"

;;

CRITICAL_THRESHOLD="${OPTARG}"

;;

WARNING_THRESHOLD="${OPTARG}"

;;

DEBUG=1

;;

cat <<__USAGE_END__

$0 [-C <chip>] [-S <sensors>] [-w <warn>] [-c <crit>] [-d] [-h]

-C <chip> - to read sensors on certain chip

-S <sensors> - to read sensors matching certain regexp

-w <warning> - warning rate threshold (80% by default)

-c <critical> - critical rate threshild (100% by default)

-d - to print debug info

-h - you've just done it :)

__USAGE_END__

>&2

exit ${CODE_UNKNOWN}

;;

\?)

echo "Invalid option: -${OPTARG}, see -h" >&2

exit ${CODE_UNKNOWN}

;;

echo "Option -${OPTARG} requires some argument, see -h" >&2

exit ${CODE_UNKNOWN}

;;

esac

done

if [ -z "${CHIP}" ]; then

DATA=$(/bin/sensors -u)

else

DATA=$(/bin/sensors -u "${CHIP}")

if [ $? -ne 0 ]; then

echo "Can't get sensors' data" >&2

exit ${CODE_UNKNOWN}

echo "${DATA}" | awk \

-v CriticalT="${CRITICAL_THRESHOLD}" \

-v WarningT="${WARNING_THRESHOLD}" \

-v Sensors="${SENSORS}" \

-v CodeOK="${CODE_OK}" \

-v CodeUnknown="${CODE_UNKNOWN}" \

-v CodeWarning="${CODE_WARNING}" \

-v CodeCritical="${CODE_CRITICAL}" \

-v Debug=${DEBUG} \

function Croak(Sensor, Input, Threshold) {

printf(\

"%s sensor shows %0.3f whilst its threshold is %0.3f (%0.0f%)\n", \

Sensor, Input, Threshold, Input / Threshold * 100 \

)

}

function Finish(Sensor, Input, Threshold, Alarm) {

if(Debug) {

printf( \

"Finishing the %s sensor: input is %0.3f threshold is %0.3f alarm flag is %0.3f\n", \

Sensor, Input, Threshold, Alarm \

)

}

if(length(Sensors)) {

if(Sensor !~ Sensors) {

return

}

if(Alarm > 0) {

printf("%s sensor in alarm state\n", Sensor)

exit CodeCritical

}

if(match(CriticalT, /^([[:digit:]]+)%$/, matched)) {

if ((length(Threshold) > 0) && (Input / Threshold * 100 >= matched[1])) {

Croak(Sensor, Input, Threshold)

exit CodeCritical

}

} else {

if (Input >= CriticalT) {

Croak(Sensor, Input, CriticalT)

exit CodeCritical

}

if(match(WarningT, /^([[:digit:]]+)%$/, matched)) {

if ((length(Threshold) > 0) && (Input / Threshold * 100 >= matched[1])) {

Croak(Sensor, Input, Threshold)

exit CodeWarning

}

} else {

if (Input >= WarningT) {

Croak(Sensor, Input, WarningT)

exit CodeWarning

}

// {

if(match($0, /^([^:]+):$/, matched)) {

SensorNew = matched[1]

if(length(Sensor) > 0) {

Finish(Sensor, Input, Threshold, Alarm)

}

Sensor = SensorNew

Input = ""

Threshold = ""

Alarm = ""

}

if(match($0, /^[[:space:]]+([^:]+): ([0-9\.\-]+)$/, matched)) {

Parameter = matched[1]

Value = matched[2]

if(Parameter ~ /_input$/) {

Input = Value

}

if(Parameter ~ /_(max|crit|emergency)$/) {

if (Value > Threshold) {

Threshold = Value

}

if(Parameter ~ /_alarm$/) {

Alarm = Value

}

END {

if(length(Sensor) > 0) {

Finish(Sensor, Input, Threshold, Alarm)

}

STATUS="${?}"

if [ "${STATUS}" -lt 4 ]; then

exit "${STATUS}"

else

exit "${CODE_UNKNOWN}"

Here are some examples:

check_all_sensors.sh
This command will check each sensor on each chip. It will raise the critical status when the input value is equal or greater than 100% of the threshold value. If the input value is greater or equal to 80% of the threshold value, the warning state will be raised. All threshold values are being got from the system.

check_all_sensors.sh -c 90% -w 50%
It’s almost the same, but the critical rate is 90% and the warning rate is 50%.

check_all_sensors.sh -C zaloopa -S '/^Temperature [0-9]+$/' -c 90 -w 75
Only temperature sensors on the zaloopa chip will be checked. The critical status will be raised when the absolute input value is greater or equal to 90 degrees. If it’s equal or greater than 75 degrees, the warning state will be thrown.

Also saved it to Gist.

How to determine on which hop your datagrams are being lost without the mtr utility

29th September 201516th July 2016 Vladimir Melnik

Sometimes you need to detect which host loses IP-packets being sent by you. It’s good when you can use the mtr utility, but what to do if you can’t install it?

Here’s a short and very simple script that could help you with that.

#/bin/bash

HST="8.8.8.8"
CNT="100"
DIR="$(mktemp -d /tmp/ping_XXXXXXXX)"

echo "Results will be stored to the ${DIR} directory"

for HOP in $(traceroute -n "${HST}" | sed -nr 's/^[[:space:]]*([[:digit:]]+)[[:space:]]+([[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3})[[:space:]]+.*$/\1:\2/gp'); do
    IFS_OLD="${IFS}"; IFS=":"; read -a ARR <<< "${HOP}"; IFS="${IFS_OLD}"
    ping -c "${CNT}" ${ARR[1]}" > "${DIR}/pingtrace_${ARR[0]}_${ARR[1]}" &
done

echo -n "Waiting for ${CNT} packets to be sent..."; sleep "$((CNT+3))"; echo "OK!"
grep "transmitted" "${DIR}"/*

#/bin/bash

HST="8.8.8.8"

CNT="100"

DIR="$(mktemp -d /tmp/ping_XXXXXXXX)"

echo "Results will be stored to the ${DIR} directory"

for HOP in $(traceroute -n "${HST}" | sed -nr 's/^[[:space:]]*([[:digit:]]+)[[:space:]]+([[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3})[[:space:]]+.*$/\1:\2/gp'); do

IFS_OLD="${IFS}"; IFS=":"; read -a ARR <<< "${HOP}"; IFS="${IFS_OLD}"

ping -c "${CNT}" ${ARR[1]}" > "${DIR}/pingtrace_${ARR[0]}_${ARR[1]}" &

done

echo -n "Waiting for ${CNT} packets to be sent..."; sleep "$((CNT+3))"; echo "OK!"

grep "transmitted" "${DIR}"/*

It traces the route to the destination and then run a bunch of simultaneous ping commands to all hosts found.

Also published to Gist.

IP-address Round-Robin for Postifx

24th September 201516th July 2016 Vladimir Melnik

Here’s a short and pretty self-desctriptive recipe to make your Postfix to send outgoing messages from different IP-addresses switching them on a round-robin basis.

First of all, we’ll need the list of IP-addresses in our roundabout, let’s put them to the /etc/postfix/roundabout file:

172.16.13.1
172.16.13.2
172.16.13.3
172.16.13.4

172.16.13.1

172.16.13.2

172.16.13.3

172.16.13.4

Then we’ll need the script to add IP-address aliases to our network interface. Surely, you can add them to the operating system configuration, but I’d suggest you to keep them all to the same /etc/postfix/roundabout file, so let’s put it to the /root/bin/roundabout_aliases.sh file:

#!/bin/bash

PATH=/bin:/sbin

ROUNDABOUT_SPOOL=/etc/postfix/roundabout
DEVICE=eth0

if [ ! -r "${ROUNDABOUT_SPOOL}" ]; then
        echo "Can't read Roundabout configuration (${ROUNDABOUT_SPOOL})" >&2
        exit 13
fi

COUNT=0
FOUND=0

ADDRESSES=($(ip addr show "${DEVICE}" | sed -r -n "s/^[[:space:]]*inet ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})\/([0-9]{1,2}).*$/\1/gp"))

while read LINE; do

        ADDRESS=$(echo "${LINE}" | sed -nr "s/^[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")
        if [ -z "${ADDRESS}" ]; then
                continue
        fi

        for TEST in ${ADDRESSES[@]}; do
                if [ "${TEST}" = "${ADDRESS}" ]; then
                        continue 2;
                fi
        done

        ip address add "${ADDRESS}" dev "${DEVICE}"

done < "${ROUNDABOUT_SPOOL}"

#!/bin/bash

PATH=/bin:/sbin

ROUNDABOUT_SPOOL=/etc/postfix/roundabout

DEVICE=eth0

if [ ! -r "${ROUNDABOUT_SPOOL}" ]; then

echo "Can't read Roundabout configuration (${ROUNDABOUT_SPOOL})" >&2

exit 13

COUNT=0

FOUND=0

ADDRESSES=($(ip addr show "${DEVICE}" | sed -r -n "s/^[[:space:]]*inet ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})\/([0-9]{1,2}).*$/\1/gp"))

while read LINE; do

ADDRESS=$(echo "${LINE}" | sed -nr "s/^[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")

if [ -z "${ADDRESS}" ]; then

continue

for TEST in ${ADDRESSES[@]}; do

if [ "${TEST}" = "${ADDRESS}" ]; then

continue 2;

done

ip address add "${ADDRESS}" dev "${DEVICE}"

done < "${ROUNDABOUT_SPOOL}"

If we want this script to be invoked automatically when the network interface starts, let’s create or modify the /sbin/ifup-local script (if we have a CentOS/RedHat-based system):

#!/bin/sh

if [ "$1" -eq "eth0" ]; then
        /root/bin/roundabout_aliases.sh
fi

#!/bin/sh

if [ "$1" -eq "eth0" ]; then

/root/bin/roundabout_aliases.sh

And now, the last, but not ever least, let’s implement the little script to change the smtp_bind_address value in our /etc/postfix/postfix.conf configuration. Let’s call it /root/bin/roundabout-postfix.sh:

#!/bin/bash

PATH=/bin:/sbin:/usr/sbin

ROUNDABOUT_SPOOL=/etc/postfix/roundabout
POSTFIX_CONFIG=/etc/postfix/main.cf

if [ ! -r "${POSTFIX_CONFIG}" ]; then
echo "Can’t read Postfix configuration (${POSTFIX_CONFIG})" >&2
exit 13
fi

SMTP_BIND_ADDRESS=$(cat "${POSTFIX_CONFIG}" | sed -nr "s/^[[:space:]]*smtp_bind_address[[:space:]]*=[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")

if [ -z "${SMTP_BIND_ADDRESS}" ]; then
        echo "Can’t determine the current IP-address" >&2
        exit 13
fi

if [ ! -r "${ROUNDABOUT_SPOOL}" ]; then
        echo "Can’t read Roundabout configuration (${ROUNDABOUT_SPOOL})" >&2
        exit 13
fi

COUNT=0
FOUND=0

while read LINE; do

        ADDRESS=$(echo "${LINE}" | sed -nr "s/^[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")
        if [ -z "${ADDRESS}" ]; then
                continue
        fi

        COUNT=$((COUNT+1))
        if [ "${COUNT}" -eq 1 ]; then
                ADDRESS1="${ADDRESS}"
        fi

        if [ "${FOUND}" -eq 1 ]; then
                SMTP_BIND_ADDRESS_NEW="${LINE}"
                break
        fi

        if [ "${LINE}" = "${SMTP_BIND_ADDRESS}" ]; then
                FOUND=1
        fi

done < "${ROUNDABOUT_SPOOL}"

if [ -z "${ADDRESS1}" ]; then
        echo "There are no entries in the Roundabout spool" >&2
        exit 13
fi

if [ -z "${SMTP_BIND_ADDRESS_NEW}" ]; then
        SMTP_BIND_ADDRESS_NEW="${ADDRESS1}"
fi

sed -r -i -e "s/^[[:space:]]*smtp_bind_address[[:space:]]*=[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/smtp_bind_address = ${SMTP_BIND_ADDRESS_NEW}/i" "${POSTFIX_CONFIG}"

if [ "${?}" -ne 0 ]; then
        echo "Something went wrong :-(" >&2
        exit 13
fi

postfix reload >/dev/null 2>&1

if [ "${?}" -ne 0 ]; then
        echo "Something went wrong :-(" >&2
        exit 13
fi

#!/bin/bash

PATH=/bin:/sbin:/usr/sbin

ROUNDABOUT_SPOOL=/etc/postfix/roundabout

POSTFIX_CONFIG=/etc/postfix/main.cf

if [ ! -r "${POSTFIX_CONFIG}" ]; then

echo "Can’t read Postfix configuration (${POSTFIX_CONFIG})" >&2

exit 13

SMTP_BIND_ADDRESS=$(cat "${POSTFIX_CONFIG}" | sed -nr "s/^[[:space:]]*smtp_bind_address[[:space:]]*=[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")

if [ -z "${SMTP_BIND_ADDRESS}" ]; then

echo "Can’t determine the current IP-address" >&2

exit 13

if [ ! -r "${ROUNDABOUT_SPOOL}" ]; then

echo "Can’t read Roundabout configuration (${ROUNDABOUT_SPOOL})" >&2

exit 13

COUNT=0

FOUND=0

while read LINE; do

ADDRESS=$(echo "${LINE}" | sed -nr "s/^[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/\1/pi")

if [ -z "${ADDRESS}" ]; then

continue

COUNT=$((COUNT+1))

if [ "${COUNT}" -eq 1 ]; then

ADDRESS1="${ADDRESS}"

if [ "${FOUND}" -eq 1 ]; then

SMTP_BIND_ADDRESS_NEW="${LINE}"

break

if [ "${LINE}" = "${SMTP_BIND_ADDRESS}" ]; then

FOUND=1

done < "${ROUNDABOUT_SPOOL}"

if [ -z "${ADDRESS1}" ]; then

echo "There are no entries in the Roundabout spool" >&2

exit 13

if [ -z "${SMTP_BIND_ADDRESS_NEW}" ]; then

SMTP_BIND_ADDRESS_NEW="${ADDRESS1}"

sed -r -i -e "s/^[[:space:]]*smtp_bind_address[[:space:]]*=[[:space:]]*([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})[[:space:]]*\$/smtp_bind_address = ${SMTP_BIND_ADDRESS_NEW}/i" "${POSTFIX_CONFIG}"

if [ "${?}" -ne 0 ]; then

echo "Something went wrong :-(" >&2

exit 13

postfix reload >/dev/null 2>&1

if [ "${?}" -ne 0 ]; then

echo "Something went wrong :-(" >&2

exit 13

You can run this script by cron or when certain event happens (e.g., when the current IP-address has been blacklisted).

And don’t forget to add something like smtp_bind_address = 0.0.0.0 to the /etc/postfix/main.cf file before to run this script for the first time, in other case it won’t find the IP-address to be changed! 🙂

Did you foresaw your future life when you were younger?

11th August 201511th August 2015 Vladimir Melnik

At some point you may start to realize that you had foreseen all your furure life and all future events in the world around you quite a long time ago. Were there some dreams or some unexpected thoughts, even some past things that you could now consider as pretty obvious signs – all these things were quite obvious, so you somehow knew that your life will go this way or that one.

]Are you familiar with that feeling? If yes – what do you think, doesn’t that mean that you’ve made the world around you by your imagination?

Living my music

4th August 20155th August 2015 Vladimir Melnik

I really love music! I love to listen music, to feel it, to compose my tunes and to play them. I’m pretty sure that principles of musical harmonies, chords and progressions can be applied to varions things in the universe, because the world itself seem to be organized by the same rules. Surely, I’m not an expert in physics and mathematics, but you don’t need to be a PhD to see the obvious. 🙂

I decided to try an odd experiment. I’ve divided the week to 12 equal chunks complied to 12 halftones, so one week is treated as a full octave. It could look like that:

Then I’m going to “play” various chords progressions, just by doing certain things at certain hours corresponding to certain tones. For example, “playing” a C-chord means doing some things in the following periods:

from 00:00 till 14:00 of Monday,
from 08:00 till 22:00 of Wednesday,
from 02:00 till 16:00 of Friday.

On the next week I’ll “play” some other chord, for example, an Am-chord. Then goes an F-chord. And then – a G-chord. So, some progression will be “played”.

What it gives? I don’t know yet! 🙂 I need to try and then I could tell about results.

What exactly I’ll do at these hours? I’m going to decide it. But, just kind of wondering, what would YOU do at some *magic* time periods if you knew they’re *magic*?

Thank you!

Virtualization Cluster Network in a Nutshell

21st July 20154th August 2015 Vladimir Melnik

To be honest, I’m not keen on drawing diagrams, but today I had to spend a couple of hours to sketch this one. It was needed to illustrate Ethernet-links between elements of customer’s physical infrastructure (we’re building a virtualization cluster for them).

As you might know, Apache CloudStack can help you to build a redundant cluster, it means that you can run your virtual instances on 2 virtualization hosts, and when one host needs to be shutdown all virtual instances migrates to another host.

I hope, this chart could be helpful to people who’re going to set up a networking environment for Apache CloudStack-driven cloud. This drawing seems to be pretty self-descriptive, but feel free to ask any questions if you have some. 🙂

A simple todo list for your shell

2nd March 201516th July 2016 Vladimir Melnik

This simple script lists today’s tasks every time you log in (or create a new window in your screen).

# Just add me to your .bashrc:
# [ -x ~/.bashrc_today ] && . ~/.bashrc_today

TODAYD="${HOME}/.today.d"

if [ ! -d "${TODAYD}/today" ]; then
        mkdir -p "${TODAYD}/today"
fi

TODAY=$(date +%F)

function toDay() {
        local DAY=${1};  shift;
        local CARD=${1}; shift;
        local TODO=${*}
        (
                if [ ! -d "${TODAYD}/${DAY}" ]; then
                        mkdir -p "${TODAYD}/${DAY}"
                fi
        ) && (
                echo "${TODO} [+${TODAY}]" >> "${TODAYD}/${DAY}/${CARD}"
        ) && (
                echo -n "${TODAYD}/${DAY}/${CARD}: "
                cat "${TODAYD}/${DAY}/${CARD}"
        )
}

echo -n -e "Today is \033[0;36m$(date +%A)\033[0m, \033[0;35m${TODAY}\033[0m"

if [ -d "${TODAYD}/${TODAY}" ] && STUFF=$(ls "${TODAYD}/${TODAY}") && [ -n "${STUFF}" ]; then
        for CARD in ${STUFF}; do
                (cat "${TODAYD}/${TODAY}/${CARD}" >> "$TODAYD/today/${CARD}") &&
                        rm -f "${TODAYD}/${TODAY}/${CARD}"
        done
        rmdir "${TODAYD}/${TODAY}"
fi

if [ -d "${TODAYD}/today" ] && STUFF=$(ls -X "${TODAYD}/today/") && [ -n "${STUFF}" ]; then
        echo \ and here\'s what to do:
        for CARD in ${STUFF}; do
                echo -n -e " * \033[1;33m(\033[1;37m${CARD}\033[1;33m)\033[0m "
                cat "${TODAYD}/today/${CARD}"
        done
        echo Good luck!
else
        echo , don\'t you know what to do? =\)
fi

echo

# Just add me to your .bashrc:

# [ -x ~/.bashrc_today ] && . ~/.bashrc_today

TODAYD="${HOME}/.today.d"

if [ ! -d "${TODAYD}/today" ]; then

mkdir -p "${TODAYD}/today"

TODAY=$(date +%F)

function toDay() {

local DAY=${1}; shift;

local CARD=${1}; shift;

local TODO=${*}

(

if [ ! -d "${TODAYD}/${DAY}" ]; then

mkdir -p "${TODAYD}/${DAY}"

) && (

echo "${TODO} [+${TODAY}]" >> "${TODAYD}/${DAY}/${CARD}"

) && (

echo -n "${TODAYD}/${DAY}/${CARD}: "

cat "${TODAYD}/${DAY}/${CARD}"

)

}

echo -n -e "Today is \033[0;36m$(date +%A)\033[0m, \033[0;35m${TODAY}\033[0m"

if [ -d "${TODAYD}/${TODAY}" ] && STUFF=$(ls "${TODAYD}/${TODAY}") && [ -n "${STUFF}" ]; then

for CARD in ${STUFF}; do

(cat "${TODAYD}/${TODAY}/${CARD}" >> "$TODAYD/today/${CARD}") &&

rm -f "${TODAYD}/${TODAY}/${CARD}"

done

rmdir "${TODAYD}/${TODAY}"

if [ -d "${TODAYD}/today" ] && STUFF=$(ls -X "${TODAYD}/today/") && [ -n "${STUFF}" ]; then

echo \ and here\'s what to do:

for CARD in ${STUFF}; do

echo -n -e " * \033[1;33m(\033[1;37m${CARD}\033[1;33m)\033[0m "

cat "${TODAYD}/today/${CARD}"

done

echo Good luck!

else

echo , don\'t you know what to do? =\)

echo

Adding a new task is as easy as typing something like that:

toDay 2015-13-13 universe.999 Save the universe!

1	toDay 2015-13-13 universe.999 Save the universe!

On the 13’th day of the 13’th month a new task will be added with priority 999 and on that day you may see:

Today is Saturday, 2015-13-13 and here's what to do:
flowers.001) Water the flowers [2015-04-20]
goodness.013) Do something good [2000-02-02]
universe.999) Save the universe! [2015-01-01]

Today is Saturday, 2015-13-13 and here's what to do:

flowers.001) Water the flowers [2015-04-20]

goodness.013) Do something good [2000-02-02]

universe.999) Save the universe! [2015-01-01]

Get updates from GitHub: https://gist.github.com/melnik13/200673d429c828e8a860.

Maintenance works without drama: how to inform visitors when the server has been shut down

20th February 201516th July 2016 Vladimir Melnik

Sometimes you need to shut some web-services down for a while to do some maintenance works. Of course, you have warned all users about the scheduled downtime period, but what if it’s just impossible to inform all potential victims, e.g. every potential visitor of some web-site that won’t be working? It’s a good idea to take care of those people (or bots) and to let them know what’s going on and when their websites is up. It’s easy to make a web-server showing some maintenance notice, but what if you need to shut the server down completely? If it’s a single server, not a cluster, what visitors will see when you shut it down? They will wait for the page to be loaded, but a message saying that the connection is timed out will be the only reward for their patience. It would be much better to let them know that you’re apologizing for inconveniences, working hard to fix the issue and have some prognosis on when it’ll be okay.

So, let’s involve some spare web-server (supposedly, you have some, don’t you?) and make it showing some calming message for users and visitors of their web-sites. It’s quite easy when you have a spare web-server connected to the same network or vlan, there are just few simple steps that needed to be performed.

Step 1: creating the announcement page

Maybe one of your colleagues has already wrote an announcement and published it where your users can read it, didn’t they? If yes – let’s take the text for the notice from there, if not – let’s write the message by ourselves. Of course, as we need it to be formatted properly, we should add some HTML-tags.

<!doctype html>
<title>Site Maintenance</title>
<style>
body { text-align: center; padding: 150px; }
h1 { font-size: 50px; }
body { font: 20px Helvetica, sans-serif; color: #333; }
article { display: block; text-align: left; width: 650px; margin: 0 auto; }
a{ color: #dc8100; text-decoration: none; }
a:hover { color: #333; text-decoration: none; }
</style>

<article>
<h1>We&rsquo;ll be back soon!</h1>
<div>
<p>Sorry for the inconvenience but we&rsquo;re performing some planned maintenance at the moment. If you need to you can always contact our support team by sending a message to <a href="mailto:support@tuchacloud.com"></a> or dialing +380445835583.</p>
<p>Works can take some time, but we’ll bring this website up before 4:20 of April 20th, 2015 (GMT)!</p>
<p>&mdash; The Team of <a href="https://tuchacloud.com/">TuchaCloud</a></p>
</div>
</article>

<!doctype html>

<title>Site Maintenance</title>

<style>

body { text-align: center; padding: 150px; }

h1 { font-size: 50px; }

body { font: 20px Helvetica, sans-serif; color: #333; }

article { display: block; text-align: left; width: 650px; margin: 0 auto; }

a{ color: #dc8100; text-decoration: none; }

a:hover { color: #333; text-decoration: none; }

</style>

<div>

<p>Sorry for the inconvenience but we’re performing some planned maintenance at the moment. If you need to you can always contact our support team by sending a message to <a href="mailto:support@tuchacloud.com"></a> or dialing +380445835583.</p>

<p>Works can take some time, but we’ll bring this website up before 4:20 of April 20th, 2015 (GMT)!</p>

<p>— The Team of <a href="https://tuchacloud.com/">TuchaCloud</a></p>

</div>

</article>

Lots of thanks to Pitch for the sample!)

Now let’s put this page somewhere, for example to /var/www/vhosts/13.13.13.13/maintenance.html.

Step 2: configuring nginx

No, I won’t believe you don’t know how to install nginx on your operating system. So let’s suppose you’ve done it already and we only need to add the following server stanza to its configuration:

server {
  listen  13.13.13.13:80 default_server;

  access_log /var/log/nginx/13.13.13.13-maintenance-access.log;
  error_log  /var/log/nginx/13.13.13.13-maintenance-error.log;

  location ~ .* {
    return 503;
  }

  error_page 503 /maintenance.html;

  location = /maintenance.html {
    charset utf-8; # in case you'd like to use it
    root /var/www/vhosts/13.13.13.13/;
    break;
  }
}

server {

listen 13.13.13.13:80 default_server;

access_log /var/log/nginx/13.13.13.13-maintenance-access.log;

error_log /var/log/nginx/13.13.13.13-maintenance-error.log;

location ~ .* {

return 503;

}

error_page 503 /maintenance.html;

location = /maintenance.html {

charset utf-8; # in case you'd like to use it

root /var/www/vhosts/13.13.13.13/;

break;

}

Step 3: interception

If the spare server is in the same IP-network with our 13.13.13.13, it’s easy to make it receive all requests intended for 13.13.13.13, just add an according alias to the network interface, for example:

ifconfig eth0:0 13.13.13.13/24

1	ifconfig eth0:0 13.13.13.13/24

Well, that’s all! Just don’t forget to update the information on the maintenance page when you realize you won’t bring the service up in time you’ve promised! 🙂

How to check some host by arping without looking up the corresponding network interface?

14th February 201516th July 2016 Vladimir Melnik

Sometimes you have to check if some host replies on ARP “who-has” requests instead of simply pinging it. You probably need it when the host has its firewall configured to deny ICMP “echo” request (as you have probably noticed, most of hosts running Microsoft Windows Server are configured to ignore these requests) to check if the host is up. So, arping really helps, but to use it you have to look up the network interface on which you shall call for this host.

This simple script does it for you: it looks up for the corresponding network interface and calls the arping utility.

#!/bin/sh

if [ -z "${1}" ]; then
        echo "Chocho?" >&2
        exit 1
fi

HOSTIP="${@: -1}"

ROUTE=$(ip route get "${HOSTIP}")
        if [ -z "${ROUTE}" ]; then
        echo "Can't find the route to this host" >&2
        exit 1
fi

IFACE=$(echo "${ROUTE}" | sed -rn "s/^.*dev (eth.[0-9\.]+)[[:space:]]+.*$/\1/gp")
        if [ -z "${IFACE}" ]; then
        echo "Can't find the interface of this host" >&2
        exit 1
fi

exec arping -I "${IFACE}" ${@}

#!/bin/sh

if [ -z "${1}" ]; then

echo "Chocho?" >&2

exit 1

HOSTIP="${@: -1}"

ROUTE=$(ip route get "${HOSTIP}")

if [ -z "${ROUTE}" ]; then

echo "Can't find the route to this host" >&2

exit 1

IFACE=$(echo "${ROUTE}" | sed -rn "s/^.*dev (eth.[0-9\.]+)[[:space:]]+.*$/\1/gp")

if [ -z "${IFACE}" ]; then

echo "Can't find the interface of this host" >&2

exit 1

exec arping -I "${IFACE}" ${@}

Just run it with any parameters you’d like to pass to arping, it will add the “-I” parameter and execute arping.

If I ever update this script, you can get the fresh version from GitHub: https://gist.github.com/melnik13/fb2a05d4084a6c039ccb.

P.S. I’d also suggest you to use arping by Thomas Habets – it doesn’t require you to indicate the interface, as it determines it by itself.

How to restart some service when server’s load average goes high as fuck

13th February 201516th July 2016 Vladimir Melnik

This post’s name and script’s comments are pretty descriptive, right? 🙂

#!/bin/bash
#
# Just put it to your crontab:
#
# * * * * * root /root/bin/lalala.sh --la1 50 --la5 20 --laf 10 --service httpd --kill --process httpd
#
# It will kill all httpd processes and restart httpd service when LA1 becomes greater or equal to 50, LA5 - to 20 and LA15 - to 10
#

PATH=/bin:/sbin:/usr/bin

OPTS=$(getopt -n $(basename ${0}) -o 1:5:f:s:kp: -l la1:,la5:,laf:,service:,kill,process: -- "${@}")
if [ "${?}" -ne 0 ]; then
        echo "Can't get options" >&2
        exit 1
fi
eval set -- "${OPTS}"
while :; do
        case "${1}" in
                -1|--la1)
                        THR1="${2}"; shift 2;;
                -5|--la5)
                        THR5="${2}"; shift 2;;
                -f|--laf)
                        THR15="${2}"; shift 2;;
                -s|--service)
                        SERVICE="${2}"; shift 2;;
                -k|--kill)
                        KILL="1"; shift 1;;
                -p|--process)
                        PROCESS="${2}"; shift 2;;
                --)
                        shift; break;;
                *)
                        echo "Can't recognize the option: ${1}"; exit 1;;
        esac
done
if [ -z "${SERVICE}" ]; then
        echo "Can't understand what service shall I restart" >&2
        exit 1
fi
if [ "${KILL}" ] && [ -z "${PROCESS}" ]; then
        echo "Can't understand what process shall I kill" >&2
        exit 1
fi

LA=$(  uptime | sed -r 's/^.*load average: ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?$/\1\t\3\t\5/g' )
LA1=$( echo "${LA}" | cut -f1)
LA5=$( echo "${LA}" | cut -f2)
LA15=$(echo "${LA}" | cut -f3)

if
        [ -n "${THR1}"  ] && [ -n "${LA1}"  ] && [ "${LA1}"  -ge "${THR1}"  ] &&
        [ -n "${THR5}"  ] && [ -n "${LA5}"  ] && [ "${LA5}"  -ge "${THR5}"  ] &&
        [ -n "${THR15}" ] && [ -n "${LA15}" ] && [ "${LA15}" -ge "${THR15}" ];
then
        if [ "${KILL}" ]; then
                while PIDS=$(pidof ${PROCESS}); do
                        echo "Slaying ${PIDS}..."
                        kill -9 ${PIDS}
                        sleep 1
                done
                sleep 10
        else
                service "${SERVICE}" restart
        fi
fi

#!/bin/bash

# Just put it to your crontab:

# * * * * * root /root/bin/lalala.sh --la1 50 --la5 20 --laf 10 --service httpd --kill --process httpd

# It will kill all httpd processes and restart httpd service when LA1 becomes greater or equal to 50, LA5 - to 20 and LA15 - to 10

PATH=/bin:/sbin:/usr/bin

OPTS=$(getopt -n $(basename ${0}) -o 1:5:f:s:kp: -l la1:,la5:,laf:,service:,kill,process: -- "${@}")

if [ "${?}" -ne 0 ]; then

echo "Can't get options" >&2

exit 1

eval set -- "${OPTS}"

while :; do

case "${1}" in

-1|--la1)

THR1="${2}"; shift 2;;

-5|--la5)

THR5="${2}"; shift 2;;

-f|--laf)

THR15="${2}"; shift 2;;

-s|--service)

SERVICE="${2}"; shift 2;;

-k|--kill)

KILL="1"; shift 1;;

-p|--process)

PROCESS="${2}"; shift 2;;

--)

shift; break;;

echo "Can't recognize the option: ${1}"; exit 1;;

esac

done

if [ -z "${SERVICE}" ]; then

echo "Can't understand what service shall I restart" >&2

exit 1

if [ "${KILL}" ] && [ -z "${PROCESS}" ]; then

echo "Can't understand what process shall I kill" >&2

exit 1

LA=$( uptime | sed -r 's/^.*load average: ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?$/\1\t\3\t\5/g' )

LA1=$( echo "${LA}" | cut -f1)

LA5=$( echo "${LA}" | cut -f2)

LA15=$(echo "${LA}" | cut -f3)

[ -n "${THR1}" ] && [ -n "${LA1}" ] && [ "${LA1}" -ge "${THR1}" ] &&

[ -n "${THR5}" ] && [ -n "${LA5}" ] && [ "${LA5}" -ge "${THR5}" ] &&

[ -n "${THR15}" ] && [ -n "${LA15}" ] && [ "${LA15}" -ge "${THR15}" ];

then

if [ "${KILL}" ]; then

while PIDS=$(pidof ${PROCESS}); do

echo "Slaying ${PIDS}..."

kill -9 ${PIDS}

sleep 1

done

sleep 10

else

service "${SERVICE}" restart

Of course, you can get all further updates of this script from GitHub: https://gist.github.com/melnik13/04225e4e60a8d66f9ab6.

Now you can sleep tight in the night! 🙂

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Step 1: creating the announcement page

Step 2: configuring nginx

Step 3: interception

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