iRule for URL persistence

Basically, if the URI contains "123456," go to server 1 and if it contains "456788," goes to server 2?

Maybe something like this?

when HTTP_REQUEST {

    Check for /install/ or /scripts/ in the path
   switch -glob [HTTP::path] {
      "*/install/*" {

          Parse the URI "directory" after install. Look for /install/, skip 9 characters and match up to the next /.
 set session_id [findstr [HTTP::path] /install/ 9 /]
      }
      "*/scripts/*" {
          Parse the URI "directory" after scripts. Look for /scripts/, skip 9 characters and match up to the next /.
 set session_id [findstr [HTTP::path] /scripts/ 9 /]
      }
      default {
 set session_id ""
      }
   }
   if {$session_id ne ""}{

       Persist on the parsed session ID for X seconds
      persist uie $session_id 1800
   }
}

Aaron

Actually, this might not work. With the above approach, the client could get load balanced to a different server than the one that generated the session. To avoid this scenario, you'd need to parse the persistence token in the response and then persist on it in subsequent requests.

 

 

Does the application include the session ID in a redirect or other HTTP response header? If so, you could parse the session ID relatively easily. Else, you'd need to look through the response content. For the latter approach, there's a codeshare example:

 

 

Persist client on response content with stream

 

http://devcentral.f5.com/wiki/default.aspx/iRules/Persist_client_on_response_content_with_stream

 

 

If you can clarify whether this is a problem and if so where the session ID can be found when it's initially created, we can provide you with more suggestions.

 

 

Aaron

Thank you very much Aaron.

 

 

But in my enviroment, the 6 characters string is the identifier.

 

 

 

http://test.big-ip.com/install/123456/whateverxxxxxx

 

 

http://test.big-ip.com/scripts/456788/whateverxxxxx

 

 

 

It is as Mr. Chris Miller said, "if the URI contains "123456," go to server 1 and if it contains "456788," goes to server 2"

 

 

So I want to know how i can "grep" the 6 characters string from the url and then set it as "session_id" and then "persist" the connection.

 

 

I don't have any idea for the iRule Syntax for doing that, so please advise me. Thanks a lot~

 

 

You don't necessarily need to set it as a sessionid, you should simply be able to send the request to server x.

I assume switch -glob would be the most efficient way to go, but someone can correct me.

when HTTP_REQUEST {
   switch -glob [HTTP::uri] {
     "*123456*" { pool poolname member x.x.x.x y }
     "*456788*" { pool poolname member x.x.x.x y }
}}

In the above, poolname = the name of your pool. x.x.x.x = the ip address of the server and y = the port on which the pool member is listening.

Aaron - this look good?

That should work fine, Chris. There's no need for persistence technically, if you're going to use the iRule for redirection every time anyway. You could of course set persistence within the switch, but that's only if you want to be able to get the user back to the same server without the use of the iRule.

 

 

Colin

Thank you very much Chris~~

 

 

Actually the 6 characters string is a random number that is generated from the web client. (Once the random number is generated, that number will be the same during the transactions) So i need to use that string as the identifier to persist the connection.

 

 

 

 

http://test.big-ip.com/install/123456/whateverxxxxxx

 

 

 

 

In my case, the 5th field of the url is the 6 characters string. (is that right?)

 

 

So to get the 5th field in the url, i used [getfield [HTTP::uri] "/" 5] .

 

 

 

 

when HTTP_REQUEST {

 

set session_id [getfield [HTTP::uri] "/" 5]

 

if {$session_id ne ""} {

 

persist uie $session_id 1800

 

}

 

}

 

 

 

I tried the above iRule in my F5 but it seems not work, the connection cannot be persist.

 

 

any thing wrong in my iRule ?

 

 

Thank you for your help.

 

 

I think you'd need to parse the random token from the response and create a persistence record then. Else, just by just looking at the request, the client would be load balanced again and then on that response LTM would add a persistence record. If the random token is only found in the response headers you could use HTTP::header $header_name to parse it and then add a persistence record with the persist add command. Else, if the token is in the response payload, you could use a stream profile and iRule like this:

 

 

Persist client on response content with stream

 

http://devcentral.f5.com/wiki/default.aspx/iRules/Persist_client_on_response_content_with_stream

 

 

A much simpler option would be to persist all requests using cookie insert persistence. This could be done without an iRule.

 

 

Aaron

So, it's not the "123456" that determines which server to go to, but the "xxxxxxx" part?

 

 

I like Aaron's idea of persisting based on the response...that's very similar to how I handle persistence for my site.

I have a environment , can't use insert client ip in the http head , but the device(is not the end client ) in front of f5 coult insert the client ip in the url in the follow format ,:

 

http://test.big-ip.com/ebv/rbv&clientIP=192.168.1.5?svk

 

 

Does the follow irules "

 

when HTTP_REQUEST {

 

set session_id [getfield [HTTP::uri] "/" 11]

 

if {$session_id ne ""} {

 

persist uie $session_id 1800

 

}

 

}

 

 

"

 

work ?

 

Does anyone have similar environment with me? Or can provide me any iRule sample to do this?

 

 

thanks !