The sooner you catch that breakage, the easier it is to get the resources (either from that team, or from your own team) to fix it. It’s a matter of “Oh we changed that API 2 months ago, everything is fine for us, all of our people have moved on to other tasks” versus “Oh our change broke you? We can revert it until we have a workaround”.
2 months, in most orgs, is enough time to figure something out before your entire business goes offline.
Unless you want that automatic update tool on your server, which I find a bit sketchy.
Where else would you put it? You could put an ACME client somewhere else but it still needs to connect to place the updated certs.
* Server mints an arbitrary key pair, it produces a CSR with the public key in it, signed using the private key, and the administrator manually copies this to an external ACME client.
* ACME client uses the CSR and control over DNS to get Let's Encrypt (or any ACME CA) to issue periodically, say, once every 45 days or as soon as possible if that's exceeded.
* Server periodically fetches any new certificates for its name from any public source of them. You can build your own server, you can use crt.sh, you can use Google, it doesn't matter because the certificates necessarily contain baked in proof that they're genuine.
Notice that in this design the server and ACME client don't talk to each other at all. They both have to be (at least sometimes) connected somehow to the public Internet, but they never need to connect to each other after that one time setup, they don't even need a human to manually transfer stuff, they just both do their thing and it works out.
This does mean the key remains the same for the lifetime of the server. But if you have a sane policy for servers getting replaced (e.g. they're depreciated over 36 months and replaced before 48 months) there's no reason that should pose a problem in itself.
It's one line in a crontab, hardly an enterprise level endevaour involving IBM consultants and a triple redundant K8S cluster.
> Unless you want that automatic update tool on your server, which I find a bit sketchy.
It's no sketchier than you using binaries from your distro's repo, or even the Linux kernel. I doubt you'd read either line by line to check for nefarious wrong doing.
