Few years ago i wrote this post to explain how to get a SSL certificate with let’s encypt: http://djynet.net/?p=795

They now have a docker version which is even more easy to use:

docker run -it --rm --name certbot -v "/etc/letsencrypt:/etc/letsencrypt" -p 80:80 -v "/var/lib/letsencrypt:/var/lib/letsencrypt" certbot/certbot certonly --standalone --email charles.walker.37@gmail.com -ddjynet.xyz