Forum Discussion
CraigM_17826
Altocumulus
Mar 16, 2010External Monitor not working
Hi all,
I am having some odd issues with a monitor. I have a web application I need to monitor and for whatever reason a HTPS monitor does not seem to work. The status of the pool always stays as "Unknown (Enabled)"
In desperation I am now trying to use a external monitor. Using the sample_monitor.sh script in /usr/bin/monitors as a basis for my monitor. The script uses three arguments, hostname/ip, URI and expected string. If the output of curl contains the extected string then it returns UP, else it returns DOWN.
Now the script runs and works as expected when I execute it from the command line, but when I create a external monitor to run this script with the required parameters the status of the pool remains as "Unknown". I decided to put in a debug line in the script that creates a logfile and writes to the logfile at certain points within the script. This logfile is never created which seems to inidicate the monitor is not being run.
Any ideas on why this would be the case? All I see is this in the LTM logfile once I apply the monitor to my test pool
Mar 16 15:59:12 local/bigip-u1 notice mcpd[1657]: 01070638:5: Pool member nnn.nnn.nnn.nnn:443 monitor status unchecked.
Here is the monitor shell script
!/bin/sh
LOGFN="/tmp/exam-services.log"
touch $LOGFN
echo "Starting exam-services monitor" >>$LOGFN
remove IPv6/IPv4 compatibility prefix (LTM passes addresses in IPv6 format)
IP=`echo ${1} | sed 's/::ffff://'`
PIDFILE="/var/run/`basename ${0}`.${IP}.pid"
kill of the last instance of this monitor if hung and log current pid
if [ -f $PIDFILE ]
then
kill -9 `cat $PIDFILE` > /dev/null 2>&1
fi
echo "$$" > $PIDFILE
echo "PIDFILE $PIDFILE created" >>$LOGFN
send request & check for expected response
using -k as Monash use a self signed certificate
echo "Executing CURL command" >>$LOGFN
curl -fNsvk https://${IP}/exam-services/student 2>&1 | grep -i "/exam-services" 2>&1 > /dev/null
mark node UP if expected response was received
if [ $? -eq 0 ]
then
echo "UP"
echo "Exam Services Website is up." >>$LOGFN
else
echo "DOWN"
echo "Exam Servicews Website is down." >>$LOGFN
fi
rm -f $PIDFILE
echo "Exiting exam-services monitor" >>$LOGFN
exit
and in the health monitor GUI setup screen I have
External Program: /usr/bin/monitors/examservices_monitor.sh
Arguments:
I have actually tried just specifying the scipt name unqualified in the External Program field as well and there was no difference.
Everything else is left at their default values.
As I mentioned, it all works when I run from the command line.
Regards
Craig
p.s. Sorry, omitted to mention we are running 10.0.1 Build 378.0 with HF3.
20 Replies
- CraigM_17826
Altocumulus
Hi,
the two boxes are identical models running the same software release (10.0.1 B378.0 with HF3). As I understand it we have a fairly bog standard high availability setup (active/standby).
I was just about to force a failover to the standby unit and thought I would just check to see if it all looked ok and now the pool that was using the external monitor is flagged as down. If I run the script manually it reports the remote system as up. This is very confusing.
I tried restarting the bigd service on the standby unit and it made no difference. The LTM log is reporting that it thinks the members in the pool are downMar 18 10:38:52 local/bigip-u2 notice mcpd[1672]: 01070638:5: Pool member nnn.nnn.nnn.nnn:443 monitor status down. Mar 18 10:38:52 local/tmm err tmm[2485]: 01010028:3: No members available for pool Test_HM Mar 18 10:43:20 local/bigip-u2 notice root: -bash ==> /usr/bin/bigstart restart bigd Mar 18 10:43:20 local/bigip-u2 notice mcpd[1672]: 01070410:5: Removed subscription with subscriber id BIGD_Subscriber
I'll reboot the standby unit and see if there is any change from a fresh reboot.
Craig - CraigM_17826
Altocumulus
Ok, after a clean reboot the pool the monitor is applied to is flagged as down now, depsite the fact when I run the script from the command line it works and reports the remote server as up.
This is all very confusing and somewhat frustrating. Might have to log a call over this one as I am running out of ideas.
Regards,
Craig - hwidjaja_37598
Altostratus
If you still want to experiment, try creating a simple monitor, eg.!/bin/sh echo $1 $2 >> /tmp/test.log echo UP
Do you see /tmp/test.log file increasing and the pool member UP? - CraigM_17826
Altocumulus
Hi Hum,
I'l give it a go, but to add to the confusion, the orginal internal health monitor I had which was NOT working has now started to work on the standby unit. There aren't any issues having monitors querying the same pool members is there? It almost seems to be when one monitor works the other fails.
The internal monitor was just doing a
GET /exam-services/student HTTP/1.1\r\nHost: \r\nConnection:Close\r\n
and expecting HTTP/1.1 200 OK
Although this is a HTTPS monitor it was suggested I didn't need to specify a client certificate or client key because the monitors don't use them.
Regards,
Craig - CraigM_17826
Altocumulus
Hi Hum,
just tried creating that simple monitor and assigning it to a poo. They pool is flagged as down and no log file is created.
I'm getting quite concerned that something is not right with our units.
Regards,
Craig - CraigM_17826
Altocumulus
Hi Hum,
Will do. It's getting beyond me. Thanks for all you help all the same.
Craig - hwidjaja_37598
Altostratus
Don't mention it .. It would be my pleasure if I could help you. Feel free to let us know if you need help ... - Will_F_98397
Nimbostratus
Hello, I've got a similar issue: http://devcentral-sea.f5.com/Forums/tabid/53/afv/topic/aff/32/aft/1172321/Default.aspx Have you had any luck? I'm about to raise a support call with F5.
Running BIG-IP 9.4.7 Build 320.1 Final - alipey_3652
Nimbostratus
Hi There,
I have the very same problem. My script works just fine from the command line but F5 seems to not be able to run the script. Nothing is logged in the script debug file and the server is marked as down. Is there any update on this bug? - Nadim
Nimbostratus
I had a similar issue and found that converting the fileformat=unix, within vi editor, then save resolved issue.
Help guide the future of your DevCentral Community!
What tools do you use to collaborate? (1min - anonymous)Recent Discussions
Related Content
DevCentral Quicklinks
* Getting Started on DevCentral
* Community Guidelines
* Community Terms of Use / EULA
* Community Ranking Explained
* Community Resources
* Contact the DevCentral Team
* Update MFA on account.f5.com
Discover DevCentral Connects