nginx URL rewrite using negative regex?

Question

I'm trying to redirect requests to https in nginx, unless it is of the form HOST/ANY_STRING_OF_CHARS/END_OF_URI, e.g.:

http://host.org/about # no redirect

http://host.org/users/sign_in # redirects to https://host.org/users/sign_in

This apparently works in Apache, but I don't understand how the bang works (ignore if it doesn't really work):

RewriteRule !/([a-z]+)$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R]

How can I do this in a nginx rewrite rule? This is not working as I'd hoped:

rewrite !/([a-z]+)$ https://$server_name$request_uri redirect;

This doesn't do the redirect either, in case I had the logic backwards:

rewrite /([a-z]+)$ https://$server_name$request_uri redirect;

Help please?

Answer 1

Sends a permanent redirect to the client:

server {
  listen 80;
  rewrite ^(/users/\w+)$ https://$host$1 permanent;
  ...
}

for negative match you could use:

if ($request_uri !~ "^/users/\w+$")
{
  return 301 https://$host$request_uri;
}

Answer 2

set $test "0";
if ($request_uri ~ "condition") {
   set $test "1";
}
if ($test ~ "0") {
   return 301 redirect url;
}