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eLeCtRoN's avatar
eLeCtRoN
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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 [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"}{
         pool "pool_body"
      } elseif {[string tolower [HTTP::uri]] starts_with "/dev"}{
         pool "pool_dev"
      }
   }
}

so now I want to integrate in this iRule a decision, for the /body should be an header persistence active, for example the request arrives with header1 it should persist to node1 in the pool_body and with header2 it should persist to node2 in the pool_body. If is header 1 and 2 not present he should use source address persistence as fallback persistence. Is that possible ? Could someone show me an example how could I the existing iRule extend with my requirement ? 

thx

kind regards

application delivery
iRules
LTM
persistent connections
session persistency

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  • 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. 

  • eLeCtRoN's avatar
    eLeCtRoN
    Icon for Cirrus rankCirrus
    Nov 21, 2022

    Hi Mohamed,

    thx for your example, I can test it in the end of this week. If I have an feedback for you I let you know.

    kind regards