Loadbalance using names?

JC -

 

 

There was a thread about this awhile back - take a look at the discussion here for some ideas:

 

 

http://devcentral.f5.com/default.aspx?tabid=53&view=topic&forumid=5&postid=6546

 

 

(corrected the link)

 

 

JQ

 

I applied the irule and tmm/named.conf change and I keep getting this error? And I did restart the tmm...Still no luck! Does this work with 9.4.5? Thx!

 

 

Mon Dec 1 11:22:16 PST 2008 tmm tmm[10220] 01220001 TCL error: ExampleDNS CLIENT_ACCEPTED - cant read ::server_ip: no such variable while executing node $::server_ip [TCP::local_port]

 

 

iRule:

 

 

when RULE_INIT {

 

set ::hostname "example.com"

 

set ::max 10

 

set ::count 0

 

}

 

 

when CLIENT_ACCEPTED {

 

node $::server_ip 80

 

incr ::count

 

if { $::count == $::max } {

 

set ::count 0

 

NAME::lookup $::hostname

 

}

 

}

 

 

when NAME_RESOLVED {

 

log local0. "NAME_RESOLVED: [NAME::response]"

 

set ::server_ip [NAME::response]

 

}

 

 

 

You're using $::server_ip before setting a value for it. Can you try the example below instead. Also, you might want to add some error handling if the name resolution doesn't return an IP address before trying to use it for the connection. You can use IP::addr (Click here) to do this:

 
 when RULE_INIT { 
  
     Hostname to resolve address for 
    set ::hostname "example.com" 
  
     Resolve the hostname every X connections 
    set ::max 10 
  
     Force a lookup on the first connection 
    set ::count 10 
 } 
  
 when CLIENT_ACCEPTED { 
  
     Increment the global count of TCP connections 
    incr ::count 
  
     If we're over the limit, try to resolve the hostname 
    if { $::count > $::max } { 
  
       NAME::lookup $::hostname 
  
    } else { 
  
        Under the max, so use the saved IP address for this connection 
       node $::server_ip 80 
    } 
 } 
  
 when NAME_RESOLVED { 
  
    set answer [NAME::response] 
    log local0. "Received answer for $::hostname: $answer" 
  
     Check if response is an IP address 
    if {[IP::addr $answer mask 255.255.255.255]}{ 
  
        Save the most recent answer for the hostname 
       set ::server_ip $answer 
  
        Reset the count as we've successfully resolved the name 
       set ::count 0 
  
        Specify the updated IP address for this connection 
       node $::server_ip 80 
  
     Current answer wasn't an IP address, so check if there is a previous valid IP 
    } elseif {[info exists ::server_ip] and [IP::addr $::server_ip mask 255.255.255.255]}{ 
  
        Specify the updated IP address for this connection 
       node $::server_ip 80 
  
     No valid IP address to use, so take some default action? 
    } else { 
       log local0. "[IP::client_addr]:[TCP::client_port]: Error: No valid IP address for $::hostname" 
    } 
 } 
 

Aaron