irule redirection issue

The iRule that you have written will mask the URI to the user and send the modified URI to the server.

If you want the User to see the redirect you can modify your iRule slightly.

when HTTP_REQUEST {
if { [HTTP::uri] equals "/" } {
set newuri "/httpgw"
log "Incoming uri - [HTTP::uri] being translated to $newuri"
HTTP::uri $newuri
HTTP::redirect $newuri
}
}

Hope this helps, but if this is not the behavior that you are looking for let me know.