Using variable to set http file we test in a probe

Can I assume that this is being used in an EAV scripted monitor, and that the monitor works because the assigned pool members are using port 8080 (or 8080 as the alias port)? If so, there isn't a lot of scriptable flexibility in scripted monitors (odd). And generally speaking, you wouldn't be able to use the client port - a real time value from the data plane - in a management plain monitor. An external monitor may be more suitable, but based on the data plane/management plane limitation, where then would you get the port variable?

In a standard HTTP monitor, no.

In an external monitor, using cURL, absolutely. Take a look at the BASH-based sample_monitor in /config/monitors. The external monitor profile sends the IP of the pool member as $1 and the port as $2, and any arguments (potentially your receive string if not hard coded) as $3. So something like this:

!/bin/sh

 these arguments supplied automatically for all external pingers:
 $1 = IP (::ffff:nnn.nnn.nnn.nnn notation or hostname)
 $2 = port (decimal, host byte order)
 $3 and higher = additional arguments

pidfile="/var/run/$MONITOR_NAME.$1..$2.pid"

if [ -f $pidfile ]
then
    kill -9 -`cat $pidfile` > /dev/null 2>&1
fi

echo "$$" > $pidfile

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

curl -fNs http://$node_ip:$2 |grep $3 1> /dev/null

status=$?
if [ $status -eq 0 ]
then
    echo "up"
fi

rm -f $pidfile

Just make sure to remove the pidfile before echoing anything to STDOUT as bigd kills the process immediately after the echo.

!/bin/sh

 these arguments supplied automatically for all external pingers:
 $1 = IP (::ffff:nnn.nnn.nnn.nnn notation or hostname)
 $2 = port (decimal, host byte order)
 $3 and higher = additional arguments

pidfile="/var/run/$MONITOR_NAME.$1..$2.pid"

if [ -f $pidfile ]
then
    kill -9 -`cat $pidfile` > /dev/null 2>&1
fi

echo "$$" > $pidfile

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

curl -fNs http://$node_ip:$2 |grep $3 1> /dev/null

status=$?
if [ $status -eq 0 ]
then
    rm -f $pidfile
    echo "up"
else
    rm -f $pidfile
fi

Good call. Perhaps the sample monitor should be updated to reflect that.