set $is_redirect "0";

if ( $scheme = "http" ) {
      set $is_redirect "1";
}

if ( $uri ~ "^/\.well-known/acme-challenge/([-_a-zA-Z0-9]+)$" ) {
      set $is_redirect "0";
}

if ( $is_redirect ) {
      return 301 https://$server_name$request_uri;
}