Big news for both the lazy homelab admin that can set a TXT once and ultimately be more secure without spraying DNS Zone Edit tokens all over their infra AND for the poor enterprise folks that have to open a ticket and wait 3 weeks for a DNS record.
a perhaps non-obvious option is to CNAME (or NS) the `_acme_challenge` record from your main zone to another zone you can control better and can't affect production traffic the same way the main zone could. `acme-dns` is a neat little tool for exactly this, that has an https api for your ACME client to request a cert from, and a dns server to respond to dns-01 challenges from your provider.
Yeah, I have all my _acme_challenge as their own zone so that BIND can auto increment the serial number without going through the pain of locking/unlocking the entire domain and hoping you don't end up with stale data that stops syncing.
That said, I like that the current system proves that you have control of the domain at the time of renewal, and I'm not sure how setting a one-off token would achieve the same.
It will help that side of the process (although, as a sibling has noted, you can CNAME your way into a better-controlled update service), but the challenge of automating cert changes for various non-HTTP services, including various virtual or physical boxes with funky admin interfaces, remains. I don't expect that vendors will do much about that, and it will end up on admins' plates, as usual. There will be much grumbling, but fewer solutions.
There are quite many solutions. For very funky systems, you can use a cert tied to a private CA. Then you can control the cert lifetimes. Or place them behind a reverse proxy that is easier to control.
desec.io allows you to create (through the api) tightly-scoped tokens that can only update the "_acme-challenge.subdomain.example.com" domain needed for DNS-01 challenges.
I switched to them from cloudflare dns for that specific functionality and it works great.
Very good question. On e.g. AWS one could probably do something like that with a custom Lambda…? Still, would be very convenient if there was some IAM rule for that.
