external monitor always marking nodes down

I am writing a script (which borrows heavily from some devcentral examples) that will ssh to a server and test for the presence of a file. If the file is there, the host should be marked down and therefore nothing is sent to stdout. If there is no file present, the server should be marked up, so "UP" is sent to stdout.

 

 

I've configured ssh to work without typing a password, and when I run the script manually from the command line it is behaving as expected. However, when I use it as an external monitor in my LTM, the monitored nodes are consistently marked down regardless of the presence or absence of the tested file. I'm guessing I'm confused about how the LTM is interpreting the exit codes but I can't figure out what is happening exactly. Here is the script, can anyone offer any advice on what I am doing wrong?

 

 

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!/bin/bash

 

 

Log debug to local0.debug (/var/log/ltm)

 

Check if a variable named DEBUG exists from the monitor definition

 

This can be set using a monitor variable DEBUG=0 or 1

 

if [ -n "$DEBUG" ]

 

then

 

if [ $DEBUG -eq 1 ]; then echo "EAV `basename $0`: \$DEBUG: $DEBUG" | logger -p local0.debug;

 

fi

 

else

 

If the monitor config didn't specify debug, enable/disable it here

 

DEBUG=0

 

echo "EAV `basename $0`: \$DEBUG: $DEBUG" | logger -p local0.debug

 

fi

 

 

Remove IPv6/IPv4 compatibility prefix (LTM passes addresses in IPv6 format)

 

NOTE - $1 variable is IP address, and it is set automatically by the LTM.

 

IP=`echo $1 | sed 's/::ffff://'`

 

 

Check if there is a prior instance of the monitor running

 

pidfile="/var/run/`basename $0`.$IP.pid"

 

if [ -f $pidfile ]

 

then

 

kill -9 `cat $pidfile` > /dev/null 2>&1

 

echo "EAV `basename $0`: exceeded monitor interval, needed to kill ${IP} with PID `cat $pidfile`" | logger -p local0.error

 

fi

 

 

Add the current PID to the pidfile

 

echo "$$" > $pidfile

 

 

Debug

 

if [ $DEBUG -eq 1 ]

 

then

 

Customize the log statement here if you want to log the command run or the output

 

echo "EAV `basename $0`: Running ssh monitor for ${IP} using custom command" | logger -p local0.debug

 

fi

 

 

Send the request request and check the response

 

ssh -i /root/healthcheck/.ssh/healthcheck_id_rsa -l healthcheck $1 "test ! -f /tmp/server_down.txt" > /dev/null 2>$1

 

 

If the file is there, node will be marked down.

 

If file is missing, node will be marked up.

 

 

if [ $? == 0 ]

 

then

 

echo "UP"

 

if [ $DEBUG -eq 1 ]; then echo "EAV `basename $0`: Succeeded for ${IP}:$2" | logger -p local0.debug; fi

 

else

 

if [ $DEBUG -eq 1 ]; then echo "EAV `basename $0`: Failed for ${IP}:$2" | logger -p local0.debug; fi

 

fi

 

rm -f $pidfile

 

 

====

 

 

Thanks.