Renewing your certificate is really easy with just certbot renew but it does expire once per 90 days, so it’s a good idea to automate this process and stop worrying about your website being unavailable because of invalid certificate. We’ll do that with a help of cron crontab -e and enter the command below

0 0,12 * * * python -c 'import random; import time; time.sleep(random.random() * 3600)' && certbot renew

after saving a file you can list your jobs to verify our new one is in place cron -l. Our job will run twice per day just to make sure a website runs without any interruptions even if Let’s Encrypt has some issues on their side.


If you have such an error

Cert is due for renewal, auto-renewing...
Could not choose appropriate plugin: The nginx plugin is not working; there may be problems with your existing configuration.
The error was: NoInstallationError()

it means that certbot cannot find nginx installation because of a cron not having same env (especially PATH variable) that is used to lookup the executable. Fix this slightly modifying a command

0 0,12 * * *  PATH="$PATH:/sbin" python -c 'import random; import time; time.sleep(random.random() * 3600)' && certbot renew >> /var/log/certupdate.log 2>&1

There are two modifications: the first one is to point to our nginx location (check whether it’s the correct one with which nginx and the second one is to have our output in a file located within /var/log directory. That will allow us to figure out from logs potential future issues in case we have any.

Also if you want to understand better what the command above does mean here is a quick hint on crontab syntax

crontab syntax