Testing 50 servers

Here's an example from hwidjaja which uses persistence to ensure the specific pool member is selected based on an initial request with a query string parameter indicating the node that should be used. Subsequent requests are persisted to that same pool member based on the source IP address.

iRule to Select alternate pool member based on QUERY_STRING

http://devcentral.f5.com/Default.aspx?tabid=53&forumid=5&tpage=1&view=topic&postid=29295

You could modify it slightly to take advantage of the URI::query command to parse the query string parameter value:

 
 when HTTP_REQUEST { 
  
    set time_out 3600 
  
     Check query string for node parameter.  Expect a two digit number indicating the pool member 
    switch [URI::query [HTTP::uri] "node"] { 
       01 { set selected_node 192.168.49.97 } 
       02 { set selected_node 192.168.49.98 } 
       03 { set selected_node 192.168.49.99 } 
       default { 
           No node parameter in query string, so check if there  
             is an existing session table entry for this client IP 
          set selected_node [session lookup source_addr [IP::client_addr]] 
       } 
    } 
  
     Check if there was a matched node 
    if {$selected_node eq ""} { 
  
        No match, so use the default pool 
       pool [LB::server pool] 
  
    } else { 
  
        Found a match, so use that 
       pool [LB::server pool] member $selected_node 
  
        Add a session table entry based on the client IP, selected node address and the record timeout 
       session add source_addr [IP::client_addr] $selected_node $time_out 
    } 
 } 
 

Aaron