Installation:
sudo pip install letsencrypt
Usage:
sudo letsencrypt certonly --webroot -w /your/web/root/directory -d yourdomain.com
The keys will be stored in /etc/letsencrypt/live/
Sample nginx config:
listen 443 ssl;
ssl_certificate /etc/letsencrypt/live/yourdomain.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/yourdomain.com/privkey.pem;