正常letsencrypt的免費SSL證書續簽, 常常需要停止nginx
步驟：
就是先停nginx服務，然后續簽操作，在服務器上即：
1. 直接續簽證書
find / -name "certbot-auto"
/root/letsencrypt/certbot-auto
/root/certbot-auto
/root/letsencrypt/certbot-auto/certbot-auto renew --force-renew --no-self-upgrade
--force-renew 強制更新
--no-self-upgrade 不更新 letsencrypt
2. 續簽證書失敗（重新注冊證書）
執行： /root/letsencrypt/certbot-auto certonly --standalone --no-self-upgrade -d xxxxx.com
若執行報以下錯
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for xxxx.com
Cleaning up challenges
Problem binding to port 80: Could not bind to IPv4 or IPv6.
停止nginx
sudo /usr/sbin/nginx -s stop
啟動nginx
nginx -c /etc/nginx/nginx.conf
nginx -s reload
最后 用2生成的新的 fullchain.pem 和privkey.pem 替換原來舊的，即可
cp /etc/letsencrypt/live/xxx.com-0001/fullchain.pem /etc/letsencrypt/live/xxx.com/fullchain.pem
cp /etc/letsencrypt/live/xxx.com-0001/privkey.pem /etc/letsencrypt/live/xxx.com/privkey.pem
sudo /usr/sbin/nginx -t
sudo /usr/sbin/nginx -s reload
訪問網站， 可以看到證書已續簽 ！！
letsencrypt配置https 相關網址：
https://www.jianshu.com/p/0d455c7a9326
https://www.jianshu.com/p/e4def1f789c1