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