Best way to append a URI - Rewrite profile ?

Yes, it will work with HTTP and HTTPS vips both.

With the HTTPS vip, once the Client Side SSL profile has processed (decrypted) the traffic, the HTTP profile will allow the traffic to be processed by this kind of iRule.

Note, for the HTTP or HTTPS VIP to be able to use this iRule, it will have to have an HTTP profile applied.

In this case, since you want to apend the "/login" to the begining of every request, you could simplify the iRule quite a bit...

when HTTP_REQUEST {
    HTTP::uri "/login[HTTP::uri]"
}

After it finishes with the "HTTP_REQUEST" event, the value of [HTTP::uri] will then be "/login/"

As the difference between HTTP::uri and [HTTP::uri], it can be kind of a little complicated, but the for simplicity, when it is inside of "[]", to are pulling the value for analysis from the HTTP headers of the client request. When it's not, you are manipulating the HTTP headers.