Auto-Renew Let's Encrypt Certificates using `certonly`

cron.d_letsencrypt

30 2 * * 1 /usr/local/bin/renew-letsencrypt >> /var/log/le-renewal.log

renew-letsencrypt.sh

#!/bin/bash

web_service='nginx'
le_path='/opt/letsencrypt'
exp_limit=30;
configpath=/etc/letsencrypt/autodomainconfig/

for config_file in ${configpath}*.ini; do

    if [ ! -f $config_file ]; then
            echo "[ERROR] config file does not exist: $config_file"
            exit 1;
    fi

    domain=`grep "^\s*domains" $config_file | sed "s/^\s*domains\s*=\s*//" | sed 's/(\s*)\|,.*$//'`
    cert_file="/etc/letsencrypt/live/$domain/fullchain.pem"

    if [ ! -f $cert_file ]; then
        echo "[ERROR] certificate file not found for domain $domain."
    fi

    exp=$(date -d "`openssl x509 -in $cert_file -text -noout|grep "Not After"|cut -c 25-`" +%s)
    datenow=$(date -d "now" +%s)
    days_exp=$(echo \( $exp - $datenow \) / 86400 |bc)

    echo "Checking expiration date for $domain..."

    if [ "$days_exp" -gt "$exp_limit" ] ; then
        echo "The certificate is up to date, no need for renewal ($days_exp days left)."
    else
        echo "The certificate for $domain is about to expire soon. Starting webroot renewal script..."
            $le_path/letsencrypt-auto certonly -a webroot --agree-tos --renew-by-default --config $config_file
        echo "Reloading $web_service"
        rc-service $web_service reload
        echo "Renewal process finished for domain $domain"
    fi
done