add_header 'Access-Control-Allow-Origin' $http_origin;
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Requested-With';
        # required to be able to read Authorization header in frontend
        # add_header 'Access-Control-Expose-Headers' 'Authorization';

        if ($request_method = 'OPTIONS') {
                # Tell client that this pre-flight info is valid for 20 days
                add_header 'Access-Control-Max-Age' 1728000;
                add_header 'Content-Type' 'text/plain charset=UTF-8';
                add_header 'Content-Length' 0;
                return 204;
        }