Forum Discussion

scottl_82413's avatar
scottl_82413
Icon for Nimbostratus rankNimbostratus
Feb 04, 2010

Redirect via Round Robin

Hello,     I'm not sure if an iRule is the best way to do this, or if the LTM can handle it in a better way.     We're going to publish a single URL - www.url.com, but need to re...
application delivery
dev
devops
iRules
nitass's avatar
nitass
Icon for Employee rankEmployee
Mar 23, 2013
I'd like to check node availability and redirect only if the node is up and skip that node and go on to the next if it's down.can you try something like this? 

[root@ve10:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
    Round robin counter
   set static::c 0

    Round robin node
    www1.url.com = 200.200.200.101
    www2.url.com = 200.200.200.111
    www3.url.com = 200.200.200.103
    www4.url.com = 200.200.200.113
   unset static::node
   set static::node(0) "200.200.200.101"
   set static::node(1) "200.200.200.111"
   set static::node(2) "200.200.200.103"
   set static::node(3) "200.200.200.113"
}

when HTTP_REQUEST {
    Pick up round robin node
   set try 0
   while { [LB::status node $static::node($static::c)] ne "up" and $try < [array size static::node]} {
      if { $static::c == [expr {[array size static::node] - 1}] } {
         set static::c 0
      } else {
         incr static::c
      }
      incr try
   }

    Action when all nodes are down
   if { $try == [array size static::node] } {
      HTTP::respond 200 content "sorry we are not ready" noserver
      return
   }

    Send HTTP redirection
   switch $static::c {
      0 { HTTP::redirect "http://www1.url.com" }
      1 { HTTP::redirect "http://www2.url.com" }
      2 { HTTP::redirect "http://www3.url.com" }
      3 { HTTP::redirect "http://www4.url.com" }
   }

    Move to next round robin node
   if { $static::c == [expr {[array size static::node] - 1}] } {
      set static::c 0
   } else {
      incr static::c
   }
}
}