This small script will update your Unifi Controller's TLS Cert

Unifi-Letsencrypt-Updater.sh

#!/bin/bash

#########################################################
# A Small script to update the UniFi Keystore file from #
# an letsencrypt auto generated certificate.            #
#########################################################

# The Domain of the UniFi Controller
DOMAIN='unifi.lan.therudes.com'

# Update the Letsencrypt Cert
/usr/bin/letsencrypt renew

# Checking if the key has been updated.
if [ /etc/letsencrypt/live/${DOMAIN}/privkey.pem -nt /usr/lib/unifi/data/keystore ]; then
  echo "Updating UniFi Cert"

  # Stop the UniFi Controller
  /usr/bin/service unifi stop

  # Export the newly created Letsencrypt Cert
  echo 2413FB3709B05939F | /usr/bin/openssl pkcs12 -export -inkey /etc/letsencrypt/live/${DOMAIN}/privkey.pem -in /etc/letsencrypt/live/${DOMAIN}/cert.pem -name unifi -out /etc/letsencrypt/live/${DOMAIN}/keys.p12 -password stdin

  # Convert the newly created Letsencrypt Cert to UniFi's keystore format
  echo y | /usr/bin/keytool -importkeystore -srckeystore /etc/letsencrypt/live/${DOMAIN}/keys.p12 -srcstoretype pkcs12 -destkeystore /usr/lib/unifi/data/keystore -storepass aircontrolenterprise -srcstorepass 2413FB3709B05939F

  # Restart the UniFi Controller
  /usr/bin/service unifi start
fi