After I moved a domain to a new host, the original certbot certificate on the old host still included it, causing renewal errors. I explain that domains can’t be deleted from a certificate directly; instead you renew the certificate specifying only the domains you want to keep, and certbot warns about the ones being dropped. I include the commands for listing certificates and their domains, and for renewing with a reduced domain set...
A walkthrough of how I add a new domain as a virtual host to an NGINX server already managed by Certbot, showing that rerunning certbot –nginx lets me expand the existing combined certificate to cover the new domain. I also cover migrating domains with existing Porkbun-issued certificates to the same server and folding them into the combined certificate, ending with a note on revoking the now-redundant ones...
I explain why I switched from manually downloading SSL certificates from PorkBun every 90 days to using Let’s Encrypt and Certbot, prompted in part by limitations with managing Australian .au domains. It covers installing Certbot on Ubuntu with NGINX, how it reads site configs to obtain and install certificates, and the systemd timer that renews them automatically...
