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eLeCtRoN's avatar
eLeCtRoN
Icon for Cirrus rankCirrus
Nov 18, 2022

F5 iRule for persistence with header and source address persistence as fallback

Hello,  I'm not so good in iRules, but maybe someone can give me some examples, I have an VS for more than one service with an iRule like this below  when HTTP_REQUEST {    if {[string tolower [HT...
application delivery
iRules
LTM
persistent connections
session persistency
Mohamed_Ahmed_Kansoh's avatar
Mohamed_Ahmed_Kansoh
Icon for MVP rankMVP
Nov 18, 2022

Hi eLeCtRoN , 
I have a bit poor environment to test my script for you , so sorry for that. 

I have written this script for your case , Find it : 

when HTTP_REQUEST {
   if {[string tolower [HTTP::host]] starts_with "company.com"}{
      if {[string tolower [HTTP::uri]] starts_with "/human"}{
         pool "pool_human"
      } elseif { [string tolower [HTTP::uri]] starts_with "/body"}{ 
        if {[HTTP::header "xxx"] contains "header_1"}{
         pool "pool_body" member 10.10.10.10 80
      } elseif {[HTTP::header "xxx"] contains "header_2"}{ 
         pool "pool_body" member 10.10.10.20 80
      } else {
      pool "pool_body"
      persist source_addr 255.255.255.255 3600  
      }
      
       } elseif {[string tolower [HTTP::uri]] starts_with "/dev"}{
         pool "pool_dev"
      }
   }
}

> For "/body" conditions , I have added a new loop For pool members selections and persistence as well. 
> I assume you have a header "xxx" and should contain "header_1" or "header_2" to select one of pool_members 
( 10.10.10.10:80) or (10.10.10.20:80) are for examples to test the validity of my iRule script , you need to change both of them to " Pool_body" members ips and port , okay? 

> this line ( persist source_addr 255.255.255.255 3600 ) to make source address affinity persistence as a fallback ip the the first and second conditions fails , Mask " 255.255.255.255 " is to make persistence by ip not subnet , you can specify subnet if you need that , Also "3600" attribute means the duration that Big-ip stores the source ip in persistence record table . 

try it and give me your feedback , I will try to simulate this environment on my lab to see. 
> I recommend that you perform it in a test virtual server and take Packet capure to see if iRule does its job or not. 

Regards 

 

  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Icon for MVP rankMVP
    Nov 21, 2022

    eLeCtRoN , 

    > The First iRule I sent , it depends on you have a specific header but has two values (header_1 & header 2 ) 
    So persistence will take effect based on this. 

    > But when I read you request now , I thind you meant by ( header_1 & header_2) that they are header names that coming in requests not values , So that I have modified it to this iRule script : 

    when HTTP_REQUEST {
   if {[string tolower [HTTP::host]] starts_with "company.com"}{
      if {[string tolower [HTTP::uri]] starts_with "/human"}{
         pool "pool_human"
      } elseif { [string tolower [HTTP::uri]] starts_with "/body"}{ 
        if {[HTTP::header exists "header_1"] }{
         pool "pool_body" member 10.10.10.10 80
      } elseif {[HTTP::header exists "header_2"]}{ 
         pool "pool_body" member 10.10.10.20 80
      } else {
      pool "pool_body"
      persist source_addr 255.255.255.255 3600  
      }
      
       } elseif {[string tolower [HTTP::uri]] starts_with "/dev"}{
         pool "pool_dev"
      }
   }
}

     

    Try it , also I am implementing a simulated Lab to test it. 
    Hope it helps you.