Node server back to nginx server

sample.conf

upstream app_domain{
    server 127.0.0.1:4000;
}

server{

    listen 0.0.0.0:80;
    server_name heracle.service.dev;
    access_log /var/log/nginx/app_domain_access;

    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Fpr $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header X-Nginx-Proxy true;

        proxy_pass http://app_domain/;
        proxy_redirect off;
    }
}