Step-by-step guide to configure Proxmox Web GUI/API with Let’s Encrypt certificate and automatic validation using the ACME protocol in DNS alias mode with DNS TXT validation redirection to Duck DNS.
We want to use a certificate in Proxmox GUI/API issued for free by a Certificate Authority trusted by default in browsers and operating systems. The chosen Certificate Authority will be Let's Encrypt [1]. Since the issued certificates are valid for only 90 days, automating the certificate renewal process is crucial. For this purpose, the Automatic Certificate Management Environment (ACME, RFC8555) protocol will be used [2].