The Little Things

While specing out a Sharepoint 2007 to 2010 migration I discovered that the default monitor created by the application template on our big-ip LTM load balancers does not work. In seeking a solution I ran across this gentleman’s blog with a custom external monitor but found that it didn’t really work. The solution to make it work was simple (as I explained on his blog in a comment). I went ahead and extended it to be more environment generic.
Copy this script to /user/bin/monitors/sharepoint2010.sh and chmod +x the file to use.

#!/bin/bash
# A custom NTLM capable sharepoint (or other site capable) health script for your big-ip load balancers
# Zachary Loeber 01/21/2011
# Save as /usr/bin/monitors/sharepoint2010.sh
# Make executable using chmod 700 sharepoint2010.sh
# The following variables should be set to get this to work properly
#
# URI: part of the site you want to use as your monitor (ie. _layouts/recyclebin.aspx)
# LOOKFOR: what will be returned that shows the site is up (ie. deleted)
# HOSTHEAD: the host header to use for the site (ie. sharepoint.corp.contoso.com)
# NTLMUSER: an account which can access this uri (ie. svcSPLBMonitoring@corp.contoso.com)
# NTLMPASS: the password of the above user (ie. password1)
# DEBUG: optional variable for debugging purposes, can be set to 0 or 1

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

# Save the port for use in the shell command
PORT=$2

# Check if there is a prior instance of the monitor running
pidfile="/var/run/`basename $0`.$IP.$PORT.pid"
if [ -f $pidfile ]
then
 kill -9 `cat $pidfile` > /dev/null 2>&1
 echo "EAV `basename $0`: exceeded monitor interval, needed to kill ${IP}:${PORT} with PID `cat $pidfile`" | logger -p local0.error
fi

# Add the current PID to the pidfile
echo "$$" > $pidfile

####  Customize the shell command to run here. ###
# Use $IP and $PORT to specify which host/port to perform the check against
# Modify this portion of the line:
# nc $IP $PORT | grep "my receive string"
# And leave this portion as is:
# '2>&1 > /dev/null'
# The above code redirects stderr and stdout to nothing to ensure we don't errantly mark the pool member up

# Send the request request and check the response
curl -H "Host: $HOSTHEAD" -fNs --ntlm -k --user "$NTLMUSER:$NTLMPASS" \
 "http://$IP:$PORT/$URI" | grep -i "$LOOKFOR" 2>&1 > /dev/null

 # Check if the command ran successfully
# Note that any standard output will result in the script execution being stopped
# So do any cleanup before echoing to STDOUT
if [ $? -eq 0 ]
then
 echo "UP"
 rm -f $pidfile
 if [ $DEBUG -eq 1 ]; then echo "EAV `basename $0`: Succeeded for ${IP}:${PORT}" | logger -p local0.debug; fi
else
 rm -f $pidfile
 if [ $DEBUG -eq 1 ]; then echo "EAV `basename $0`: Failed for ${IP}:${PORT}" | logger -p local0.debug; fi
fi

# 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 for ${IP}:${PORT} using custom command" | logger -p local0.debug
fi

Here is an example health monitor configuration: