HTTPS (old) to HTTPS (new) Redirect with an existing VS and Client Profile

Ok, perfect, so using the below irule will help you redirect users coming to your app using an old hostname to the new hostname :

when HTTP_REQUEST {
    if { !([HTTP::header "Host"] eq "newdomain.com") } {
        HTTP::respond 301 Location "https://newdomain.com[HTTP::uri]" "Connection" "Close"
    }
}

This irule will redirect every request made to a hostname different than newdomain. You can also define the opposite :

when HTTP_REQUEST {
    if { [HTTP::header "Host"] eq "olddomain.com" } {
        HTTP::respond 301 Location "https://newdomain.com[HTTP::uri]" "Connection" "Close"
    }
}

And to conclude, if you have several old domains you want to include, you can use a string based datagroup with the below irule

when HTTP_REQUEST {
    if { [class match [HTTP::header "Host"] equals DG_OLD_DOMAINS] } {
        HTTP::respond 301 Location "https://newdomain.com[HTTP::uri]" "Connection" "Close"
    }
}