Irule query custom header

You're pretty close. Try something like this:

when HTTP_REQUEST {
    if { [HTTP::header exists AKAMAI_HEADER] } {
        if { [class match [HTTP::header AKAMAI_HEADER] equals my_data_group] } {
            set state [class match -value [HTTP::header AKAMAI_HEADER] equals my_data_group]
            switch $state {
                "value1" { }
                "value2" { }
                default {
                     what do you do if the data group value doesn't match one of your switch states?
                }
            }
        } else {
             what do you do if the AKAMAI header doesn't match a data group entry?                
        }
    } else {
         what do you do if the AKAMAI header doesn't exist?
    }
}

Thanks for that, I am hoping to enable the Akamai custom header tomorrow.

Sorry another question is it possible to use the value captured for geo based targeting as ideally I would wanted to use the IP::client_addr so wondered if the value captured could be used to set the IP::client_addr if its possible ,i.e Akamai_header equals=IP::client_addr

Are you asking if the client's source address can be altered with the HTTP header value, so that the value exists in the IP::client_addr value? If so, then no it cannot. Aside from being a potentially very dangerous thing to do, the source address is collected/evaluated at layer 3, while the HTTP header is collected much later at layer 7.

I think I might have found the answer to my question and possibly an irule I could potentially modify etc..on https://devcentral.f5.com/questions/geoip-redirection-irule:

     Parse the client IP from the CDN header
    set client_ip [HTTP::header value "Client-IP"]
    if { $client_ip eq "" }{
         The header was empty/did not exist, so use the actual client IP
        set client_ip [IP::client_addr]

I dont know if the above is valid but if I am able to do something similar as what the client_ip is used for, then I could just replace with the Akamai_Header

The above rule basically says, if the HTTP header "Client-IP" exists, use it. Otherwise use the client's true source. That will not, however, change the value of IP::client_addr], only the local variable.

Yeah I misread it but you have given me a good starting point to test with so will post back if I run into any issues thanks again for pointing me in the right direction