HTTP to HTTPS redirect when 401 received.

It's a good suggestion to explicitly save the values of HTTP::host and HTTP::uri from the request as they aren't saved by default through to the HTTP_RESPONSE event.

The syntax is slightly off though:

 
 when HTTP_REQUEST { 
    set host [HTTP::host] 
    set uri [HTTP::uri] 
 } 
  
 when HTTP_RESPONSE { 
    if {[HTTP::status] == 401]}{ 
       HTTP::redirect "https://$host/$uri" 
    } 
 } 
 

I assume you have an HTTP VIP and an HTTPS VIP and that you're applying this rule to only the HTTP VIP? If you don't have a test BIG-IP, you can create test VIPs on the production BIG-IP to check the iRule.

Aaron