This one error string had me baffled for a good half hour.
$ sudo certbot --nginx The requested nginx plugin does not appear to be installed
The Certbot Nginx Plugin
The Nginx plugin has been distributed with Certbot since version 0.9.0 and should work for most configurations. https://certbot.eff.org/docs/using.html#nginx
That wasn’t helpful at all… some soul-searching later revealed the solution.
$ sudo apt install python-certbot-nginx
$ sudo crontab -e # m h dom mon dow command # certbot renew once per 12 hours on a random minute # https://certbot.eff.org/all-instructions/ 22 3,15 * * * certbot --nginx renew --quiet
The command itself can be tested by running
$ sudo certbot --nginx --force-renewal renew
Not to worry though, if the cron has mistakes Let’s Encrypt sends will be a gentle reminder when renewal time comes.
certbot-auto from here on. The former is the command you get when installing through the OS package manager. The latter is a self-updating (by editing itself) script downloadable for distributions that don’t have certbot on package managers, like for your Raspberry Pi Server.
They used to be called
letsencrypt-auto, respectively, until just recently.