Some of my internal stuff goes out to Let's Encrypt, so I don't worry about it at all. My internal AD stuff is set for like three years. If anyone has compromised the CA, they're already past where issuing malicious certs would be useful.

I would up your root cert expiration. You can keep the root CA offline if you're concerned about compromise.

There are also ways to run LE-style automatic renewals internally, but I've never bothered because what I've described above means I don't need it.

Bump root cert to 10 years and use intermediate with shorter lifetime. root cert should be stored and processed off net.

For most of my internal services that are sitting behind Traefik I use step-ca which basically gives you a Let's Encrypt style certificate while working over the local network. The root CA has a long expiry (so might not be what you want if your goal Is a short lived root CA) but the actual certificates for each service are short lived (a touch over 24 hours from memory?)

I looked into this recently.

There's a DNS challenge designed for this exact scenario called (from memory) DNS01, but it's more of a faff than I'm willing to get involved with.

Basically you push proof that you own the domain into a DNS record instead of to a file on a web server. It requires a DNS provider that has an API and a client that speaks that API.

It also leaks private DNS stuff into the public domain.

I'd love it if someone devised an easier way. Maybe there is an easier way?

Use a secret manager?

Cert is a secret, add a small agent to your containers that pings your secret manager and gets back the current cert. Then saves / imports it (or whatever is appropriate).

MONTHLY?? That's a bit much, don't you think?

If you're regenerating certa that fast, I can't think of anything that's going to secure AND easy enough to satisfy automating this.

Whatever tool you want to use to secure the contents of the cert from its initial creation, to distribution, is fine enough. If you want super easy, use an SSH/SCP script. If you want something more elegant, think Hashicorp Vault or etcd.

Ansible is probably more effort than it's worth (plus securing the secrets of the cert), and any other config mgmt tool won't deal with the distribution portion simply, so I'd skip all of that.

DNS challenge with a reverse proxy is that answer. I've been doing this for a while now and it works great. Most other answers here are work arounds or not very robust.

This is the way: https://youtu.be/liV3c9m_OX8

I do this with authentik for sso

I have local only things like vaultwarden and external things like seafile.

Synching maybe?

Not sure if it'd fit your use case 100%, but this has been a nice middle ground solution for LE certs in my lab: https://www.certwarden.com/