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Kevin_Basler
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Aug 24, 2021

iRule logic to use multiple pools to force GTM failover on VIP

I have a VIP that has no status because the pool that it uses is determined by a policy. To add state to the VIP I've added the following iRule:

 

when HTTP_REQUEST {

if { [active_members pool1] == 0 } {

# log

 

The VIP now shows a status of green (UP). When I disable the pool members in pool1, the VIP goes down and the GTM routes traffic to another data center.

 

Since I have a VIP that has multiple pools, I need to fail the VIP if any one pool member is down.

 

I've tried these examples:

 

if { [active_members pool1] == 0 } {

# log

elseif { [active_members pool2] == 0 } {

# log

elseif { [active_members pool3] == 0 } {

# log

elseif { [active_members pool4] == 0 } {

# log

}

}

 

and...

 

when HTTP_REQUEST {

if { [active_members pool1] == 0 or [active_members pool2] == 0 or [active_members pool3] == 0 }r 

# log

}

}

 

When I take any one pool down, the VIP remains up.

 

Any suggestions?

 

Thanks

 

Kevin

1 Reply

  • Hi Kevin,

    • Create an iRule:
    ltm rule irule_poolstatus {
    when HTTP_REQUEST {
        if { [active_members pool1] == 0 || [active_members pool2] == 0 || [active_members pool3] == 0 || [active_members pool4] == 0} {
            HTTP::respond 200 content "down"
        }
        else {
            HTTP::respond 200 content "up"
        }
    }
    }
    • Create a Virtual Server with IP x.y.z.t and bind the iRule:
    ltm virtual vs_poolstatus {
        destination 1.2.3.4:http
        ip-protocol tcp
        mask 255.255.255.255
        profiles {
            http { }
            tcp { }
        }
        rules {
            irule_poolstatus
        }
        serverssl-use-sni disabled
        source 0.0.0.0/0
        source-address-translation {
            type automap
        }
        translate-address enabled
        translate-port enabled
    }
    • Create a monitor with receive string:
    ltm monitor http monitor_status {
        adaptive disabled
        defaults-from http
        interval 5
        ip-dscp 0
        recv up
        recv-disable none
        send "GET /\r\n"
        time-until-up 0
        timeout 16
    }
    • Create a pool, add the virtual server IP address as pool member and bind the monitor:
    ltm pool pool_status {
        members {
            1.2.3.4:http {
                address 1.2.3.4
                session monitor-enabled
            }
        }
        monitor monitor_status
    }
    • Create second iRule:
    when HTTP_REQUEST {
        if { [active_members pool_status] == 0} {
            # log
        }
    }
    • Add the iRule to main virtual server

    first iRule and virtual server: for "up/down response"

    pool and monitor: for receive a request to the virtual server and to see the "up/down" status

    I couldn't find a shorter solution.