Forum Discussion
BIG-IP : expected behavior of redirects in irule stack
F5 BIG-IP Virtual Edition v11.4.1 (Build 635.0) LTM on ESXi
My virtual-server has an iRule stack. In the top-level iRule ( highest-priority, lowest numerical priority), under certain conditions I set the destination pool and perform redirects ( 301 302 ) :
"mysite.com" {
pool mysite.com-pool-01
}
"mysite.co.uk" {
HTTP::respond 301 Location "http://www.mysite.co.uk[HTTP::uri]"
}
"www.mysite.com.mx" {
HTTP::redirect "http://www.mysite.com/default.aspx?c=6"
}
I know that destination pool can be reset in subsequent iRules -- and so final route might be to a different pool.
But what is expected behavior with respect to redirects ? Once
HTTP::redirectHTTP::respond3 Replies
natheCirrocumulus
HTTP::redirect and HTTP::respond are commands so the irule will issue that command and the browser, in this case, will perform the command. So, because they are client side cmds, in effect, the subsequent cmds won't be actioned, unless the redirect points back to the same VIP and irule.
Hope this is true,
N
- nitass
Employee
Once HTTP::redirect or HTTP::respond is issued, is this route immediately acted upon ? ( i.e. no further iRule processing occurs )
no, further irule will still be triggered.
Or is it possible that subsequent iRule could effect a different response ?
yes
generally what people do is either to disable further event (event disable command) or perform action on the last (lowest priority) irule (set variable in higher priority irule but execute command in the lowest one).
event
https://devcentral.f5.com/wiki/iRules.event.ashx 
ArieAltostratus
If a single criterion applies to multiple responses (i.e. HTTP::redirect and HTTP::respond) you will encounter an exception. In browsers this is usually displayed as "connection reset" and in the error logs you'll see entries for "multiple responses".
In addition to
(which I do not prefer because it universally halts all further processing) and executing the actual command last there is a third option: using a semaphore.event disable
