使用Let's Encrypt配置nginx证书

Automatically enable HTTPS on your website with EFF's Certbot, deploying Let's Encrypt certificates

主要参考：https://certbot.eff.org/lets-encrypt/centosrhel7-nginx

操作起来很简单，主要用到了下面的命令：

sudo yum install nginx
sudo certbot --nginx
sudo certbot renew --dry-run
0 0 1 * * certbot renew --post-hook "/usr/sbin/nginx -s reload"