Setup ACME DNS in Proxmox

1. Create a CNAME record in your domain provider's panel for _acme-challenge.domain.com -> _acme-challenge.alternate-domain.com
2. Create an ACME account in Proxmox.
3. Setup the ACME plugin for the domain.

   pvenode acme plugin add dns linode --api linode_v4 --data LINODE_V4_API_KEY=
   pvenode config set --acmedomain0 hv3.toast-data.center,alias=toast-server.net,plugin=linode
   pvenode config set --acme account=<account-name>

4. Order the certificate.

   pvenode acme cert order

5. Voila~

Source: https://gist.github.com/zidenis/e93532c0e6f91cb75d429f7ac7f66ba5