Script that queries pair of BIG-IP LTM to detect which one is Active

Have you considered using SNMP?

using iControl REST, you could for example query the following path with curl:

curl -sk -u admin:mypass https://my-bigip/mgmt/tm/cm/device | python -mjson.tool

This will return a json formatted list of all devices in your device group. One of the fields for each device is "failoverState", that will either return active or standby.

Hi James,

another option would be to create a HTTP-based Virtual Server for each of your traffic-groups and then assign the iRule below...

when HTTP_REQUEST {
    HTTP::respond 200 content [info hostname] Content-Type text/html
}

A simple unauthenticated HTTP request towards the Virtual Server will tell you then on which cluster unit the traffic group is running on.

Cheers, Kai