Universal persistence using header values for multiple client IPs.

Hi ajohnson,

take a look to the iRule below and tell me what you think?

The iRule uses the

CLIENT_ACCEPTED

event to differentiate between client and backend connections. If a backend connection is identified, then it will be checked during the

LB_SELECTED

event if

[LB::server addr]

(currently selected pool member) equals the

[IP::client_addr]

(backend IP address). If the IPs are matching no action is taken. But if the IPs are different the

[IP::client_addr]

will be used as new

[LB::server addr]

by executing the

[pool]

command a second time.

when CLIENT_ACCEPTED {
    if { ( [IP::client_addr] starts_with "1.2.3.4" )
      or ( [IP::client_addr] starts_with "1.2.3.5" ) } then {
        set backend_connection 1
    } else {
        set backend_connection 0
    }
}
when LB_SELECTED {
    if { $backend_connection } then {
        if { [LB::server addr] equals [IP::client_addr] } then {
             The selected node is already correct...
        } else {
            pool [LB::server pool] member [IP::client_addr] [LB::server port]
        }
    } else {
         Use LB decissions / persistence records for client connections.
    }
}

Note: The iRule can be combined with any persistence profile / LB algorythm you wish. The backend connection will be overwritten on demand without affecting client connections.

Warning: Didn't tested nor saved the iRule at all. So better apply this iRule on a test-system... 😉

Cheers, Kai