1、设置DNS地址及有效期

2、将域名设置为变量。

3、重写域名

4、去掉proxy_pass后面的反斜杠

        location /api/ {
                resolver 223.5.5.5 223.6.6.6 valid=30s;
                resolver_timeout 10s;
                set $backend "timeless.com";
                rewrite ^/api/(.*)$ /$1 break;
                proxy_pass http://$backend;

                proxy_set_header Host $backend;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }