Auto-renew Let’s Encrypt SSL certificates using crontab

The achieve this, all we need to do is add a new crontab which will trigger the certbot at a certain time in a day to check the expiry date of your SSL certificates and take care of the renewing it.

1. Configure the crontab (Make sure to use sudo so that root crontab can be configured with root privilege which will allow certbot command to be run without sudo):

$ sudo crontab -e

2. The above command will open the editor which you have configured on your system, and add the following lines in it:

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin 0 0 */10 * * certbot renew >> /logs/certbot-cron.log 2>&1

Save your crontab, and that’s all folks.

Breaking down the command for better understanding:

• Cron Expression: The first part 0 0 */10 * * is the cron expression, which basically describes individual detail of the schedule. For our case, we have scheduled it to trigger the command on every 10th day of a month at 00:00. You can create your own cron expression using this amazing site crontab.guru.
• Command: The second part is cerbot renew the command which is used to renew the SSL certificates.
• Logging: The third part is where I am saving the generated logs for future references. Using 2>&1 we are redirecting stderr to whatever value is set to stdout.
  In case you want to verify if your certificates are renewed successfully or not, run the below command:

$ sudo certbot certificates

Ref:
https://medium.com/wizpanda/centos-7-auto-renew-lets-encrypt-ssl-certificates-using-crontab-f6eec8750bd8