Priority group activation and automatically closing connections when higher priorty group goes UP.

pool_server has 6 pool members,  (A,B,C) group priortity is 10; (D,E,F) group priority is 5, tcp monitor use "tcp_delay_up_120s" and its value of "Time Until Up"  set 120s;

pool_icall members is (A,B,C), use default tcp monitor

pool_back members is (D,E,F), use default tcp monitor

user_alert.conf

alert poolserver-1-UP "Pool /Common/pool_server member /Common/192.168.100.1:23 monitor status up" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}
alert poolserver-2-UP "Pool /Common/pool_server member /Common/192.168.100.2:23 monitor status up" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}
alert poolserver-3-UP "Pool /Common/pool_server member /Common/192.168.100.3:23 monitor status up" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}

 icall config:

list sys icall handler triggered delete_backserver_session 
sys icall handler triggered delete_backserver_session {
    script delete_backserver_session
    subscriptions {
        delete_backserver_session {
            event-name delete_backserver_session
        }
    }
}

list sys icall script delete_backserver_session           
sys icall script delete_backserver_session {
    app-service none
    definition {
        foreach var {poolname} {
            set $var $EVENT::context($var)
        }
        puts "poolname is $poolname"
        exec /bin/bash /var/tmp/delete_backserver_session.sh
    }
    description none
    events none
}

chmod +x /var/tmp/delete_backserver_session.sh

#!/bin/bash
count=`tmsh list ltm pool pool_icall | grep "state up" | wc -l`
if [ $count -ge 2 ] 
then 
        for i in `tmsh show ltm pool pool_back members | grep -E "Ltm::Pool Member:" | awk '{print $NF}'`
        do 
                address=`echo $i | awk -F ":" '{print $1}'`;
                port=`echo $i | awk -F ":" '{print $2}'`
                tmsh delete sys connection ss-server-addr $address ss-server-port $port
        done
fi