conditional-nginx-block-cookie.conf

{        
        map $cookie_test $named_location_block {
                "true" "@a";
                default "@b";
        }

        server {
                listen 10503;

                location / {
                        try_files /dev/null "$named_location_block";
                }

                location @a {
                        add_header content-type text/plain;
                        return 200 'a';
                }

                location @b {
                        add_header content-type text/plain;
                        return 200 'b';
                }
        }
}