Let's Encrypt domain configuration file.

my-domain.com.conf

# Just one single domain.
domains = my-domain.com

# Key size.
rsa-key-size = 4096 # Or 2048

# The current version of Let's Encrypt (as of May 3, 2017) is using this server.
server = https://acme-v01.api.letsencrypt.org/directory

# This email address will receive renewal reminders.
email = me@my-domain.com

# This will run as a cronjob, so turn off the ncurses UI.
text = True

# Place the certs in the /var/www/letsencrypt folder (under .well-known/acme-challenge/).
authenticator = webroot
webroot-path = /var/www/letsencrypt/