Few years ago, switched my web site from a custom cms (written by Erwan Pinvidic) to moinmoin wiki engine. Some months (or years?), later I implemented an authentifcation plugin which is using my mail server as a credentials' provider. At that time, I wanted to use https for authentifcation and tried few things to force apache to redirect to https on specific url pattern, and I failed. At this stage, I modified my plugin to reject authentification if the login and password were sent over http and forgot all that stuff...

Few days ago, I setup varnish in front of my apache server and moved few http to https redirections from apache to varnish. And while updating varnish's configuration, I recalled my attempts with moinmoin's login page redirection and wanted implement this using varnish. And this time, I did it using the setup below:

sub vcl_recv {
if (req.http.host ~ "www.glennie.fr" && req.url ~ "\?action=login") {
       set req.http.x-host = req.http.host;
       set req.http.x-url = req.url;
       return(synth(750, "https://" + req.http.x-host + req.http.x-url));
    }
}


sub vcl_synth {
    if (resp.status == 750) {
      set resp.http.Location = "https://" + req.http.x-host + req.http.x-url;
      set resp.status = 301 ;
      return(deliver);
  }
}

So, don't worry if you don't succeed the first time. Try later using the right tool^TM!