https://naturepi.com/2018/08/ssl-cert-letsencrypt/

sudo docker run -it --rm --name certbot \
 -v "/data/letsencrypt/etc:/etc/letsencrypt" \
 -v "/data/letsencrypt/lib:/var/lib/letsencrypt" \
 certbot/certbot certonly --manual --preferred-challenges dns-01

按提示设置dns txt记录即可