Running Let's Encrypt Certbot in docker without any installation on the host.
HTTP validation, requires port 80 and 443 access.
docker run -it --rm --name certbot
-v "/tmp/le-etc:/etc/letsencrypt"
-v "/tmp/le-var:/var/lib/letsencrypt"
-p 80:80 -p 443:443
certbot/certbot certonly