[KronisLV]

The only thing I don't really know how to do with it is round robin DNS for many servers with LetsEncrypt HTTPS.

It feels like then I'd probably need either shared storage for the certificate files (which goes against the idea of decentralization somewhat) or to use a DNS challenge type.

Anyone have experience with something like that?

[francislavoie]

Shared storage is the solution. Caddy supports multiple different storage backends (filesystem by default, and Redis, Consul, DynamoDB via plugins) and uses the storage to write locks so that one instance of Caddy can initiate the ACME order, and another can solve the challenge. See the docs: https://caddyserver.com/docs/automatic-https#storage

I'm doing this exact thing, with the Redis plugin behind DNSRR and it works seamlessly.