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David_X_20743's avatar
David_X_20743
Icon for Nimbostratus rankNimbostratus
May 09, 2008

LB method setup and post redirect

Hi

 

 

I am new to the F5 iRules. I am currently setting up a set of of iRules for a customer and get really lost. So any suggestion will be really appreciated.

 

 

The customer wish to setup the F5 to look at the Host HTTP header and if it is

 

test.test4u.com to balance it round robin style between the two web servers 192.168.1.168 and 192.168.1.132

 

 

They also wish the F5 to look at the sysid HTTP Post variable and if this is set to 1, send the traffic to 192.168.1.168, if set to 2 send the traffic to .132 if it is not set then balance in the normal way. This is set when a user pages inside the results, and it uses the web server memory cache so it needs to go the same server that produced the result set.

 

 

I wrote the following iRules, but it does not seem to be working

 

 

when HTTP_REQUEST {

 

if { [HTTP::header "HOST"] contains "test.test4u.com" } {

 

LB::mode roundrobin

 

}

 

 

 

if { [HTTP::method] eq "POST" } {

 

if {[HTTP::header names] contains "sysid=1" } {

 

node 192.168.1.168 80

 

}

 

 

 

if {[HTTP::header names] contains "sysid=2" } {

 

node 192.168.1.132 80

 

}

 

 

}

 

 

}

 

 

Thank you
application delivery
dev
devops
iRules

2 Replies

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  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    May 09, 2008
    The post data parameter and parameter value wouldn't be accessible in an HTTP header. You'd need to collect the HTTP payload and then see if there is a sysid parameter. I think this will do what you're looking for. To use it, add a default pool to the VIP containing both nodes. If you run into issues, check the debug logging in /var/log/ltm. When you're done testing, you can comment out the log statements to save CPU/disk resources. 

      
    
 when HTTP_REQUEST {   
    
     Check if the request is a POST  
    if {[HTTP::method] eq "POST"}{  
    
       log local0. "[IP::client_addr]:[TCP::client_port]: POST request to [HTTP::uri]"  
    
        Collect the request data  
       if { [HTTP::header exists "Content-Length"] } {  
           Collect the content length as specified in the C-L header  
          set content_length [HTTP::header "Content-Length"]  
       } else {  
           Collect up to 1 Mib  
          set content_length 1000000000  
       }  
       log local0. "[IP::client_addr]:[TCP::client_port]: collecting $content_length bytes"  
           Trigger the collection of the request data if the content length isn't 0  
       if {$content_length}{  
          HTTP::collect $content_length  
       }  
    }  
  } 
 when HTTP_REQUEST_DATA {  
  
    log local0. "[IP::client_addr]:[TCP::client_port]: payload: [HTTP::payload]"  
   
    switch -glob [HTTP::payload] {  
   
       *sysid=1* {  
   Send the request to node 1  
          node 192.168.1.168 80  
          log local0. "[IP::client_addr]:[TCP::client_port]: found sysid=1, using node 1"  
       }  
       *sysid=2* {  
           Send the request to node 2  
          node 192.168.1.132 80  
          log local0. "[IP::client_addr]:[TCP::client_port]: found sysid=2, using node 2" 
       }  
       default {  
           Didn't find an expected sysid, do nothing.  Use the default pool on the VIP.  
          log local0. "[IP::client_addr]:[TCP::client_port]: didn't find sysid"  
       }  
    }  
 }

    Aaron
  • Randy_Johnson_1's avatar
    Randy_Johnson_1
    Icon for Nimbostratus rankNimbostratus
    May 20, 2009
    Aaron -

    I'm working on a semi similar setup- however, I want to do a redirect to a different URL/ URI and maintain the POST data.

    See the thread 

    http://devcentral.f5.com/Default.aspx?tabid=53&forumid=5&postid=57319&view=topic

    And I'm hoping to combine these rules to do what I need.

    However, I'm curious about the 'sysid' parameter...

    Whats it used for, and does this seem doable ?

    Thanks