Irule insert X-forward-host value

Hi everyone,

I would like to add a x-forward-host but I don't know the exact syntax to add it. The goal is that I redirect traffic to another webserver and that he knows where the client tried to connect, to avoid mixing UAT and prod traffic:

this is for the redirect (works fine): when HTTP_REQUEST { if { [ HTTP::header value Host ] equals "Uat.example.com" }{ HTTP::header replace Host "uat.destination.com" pool UAT } }

This is what I have till now for the x-forward-host (I copied it from the x-forward-for)

when HTTP_REQUEST { HTTP::header insert X-Forwarded-host [???] }

Someone any idea ?

thanks