smartRenew.sh

#!/bin/bash

#
# Based off ScottHelme's Lets Encrypt Smart Renew
# https://github.com/ScottHelme/Lets-Encrypt-Smart-Renew
#
# Repalce DOMAIN with the domain of the certificate you are renewing
# 
# crontab
# 0 * * * * /path/to/smartRenew.sh
 
# The remaining life on our certificate below which we should renew (7 days).
RENEW=21
# Set date for backup
TODAY=`date '+%Y_%m_%d'`
# If the certificate has less life remaining than we want.
if ! openssl x509 -checkend $[ 86400 * $RENEW ] -noout -in /etc/lego/certificates/DOMAIN.crt
  then
    # Then make backup copy of existing cert before starting renew
    cp /etc/lego/certificates/DOMAIN.crt /etc/lego/certificates/DOMAIN_$TODAY.crt
    # Then call the renewal script.
    /etc/lego/renew-certificate.sh
fi