SSL Certficate for Servers on Dynamic IP Addresses

cron_dehydrated_dyn.sh

#!/bin/sh
#
# Cronjob for Let's Encrypt certifcate for hosts on dynamic IP.
#
# Uses letsencrypt/acme client implemented as a shell-script 
# – just add water https://dehydrated.de
#
# Please don't use HSTS or HPKP headers on dynamic IPs as they 
# will affect other customers using your IP in the future.
#

# Hostname for dynamic IP
dyndomain=$(dig +short -x $(curl --ipv4 --silent icanhazip.com))

# Remove trailing dot
dyndomain=${dyndomain%.}

# Get cert
/usr/local/lib/dehydrated/dehydrated --cron --domain ${dyndomain}

# Update symlink (could also be implemeted in hook script)
ln --symbolic --force /etc/dehydrated/certs/${dyndomain} /etc/dehydrated/certs/dyndomain

Please don't use HSTS or HPKP headers on dynamic IPs as they will affect other customers using your IP in the future.