A virtual host setting of Nginx for proxy pass

server {
	listen 443 ssl;
	listen [::]:443;
	ssl_certificate /etc/nginx/ssl/cert.pem;
	ssl_certificate_key /etc/nginx/ssl/key.pem;

	root /var/www/html;
	index index.html index.htm index.nginx-debian.html;
 
	auth_basic    "Admin";
	auth_basic_user_file  /etc/nginx/.htpasswd;

	server_name ~^(?<subdomain>.+)\.xxxxx\.com;
	location / {
        resolver 8.8.8.8;
		if ($subdomain ~* (\w+)\-(\w+)\-(\w+)) {
    	   proxy_pass https://$1.$2.$3;
           break;
		}
		if ($subdomain ~* (\w+)\-(\w+)) {
    	   proxy_pass https://$1.$2;
           break;
		}
		if ($subdomain ~* (\w+)){
  			proxy_pass https://$1.com;
		}
	}
}