Letsencrypt renewal

Posted on September 3, 2017

I have web app running on a DO Droplet which I secured with Letsencrypt. The cert renewal has been failing it’s weekly attempt ever since 8/6. I should’ve addressed the problem sooner, but the cert has expired. In my le-renew.log I have the following error…

All renewal attempts failed. The following certs could not be renewed:
  /etc/letsencrypt/live/[domain]/fullchain.pem (failure)
IMPORTANT NOTES:
 - The following errors were reported by the server:

   Domain: [domain]
   Type:   connection
   Detail: DNS problem: SERVFAIL looking up CAA for [domain]

   To fix these errors, please make sure that your domain name was
   entered correctly and the DNS A record(s) for that domain
   contain(s) the right IP address. Additionally, please check that
   your computer has a publicly routable IP address and that no
   firewalls are preventing the server from communicating with the
   client. If you're using the webroot plugin, you should also verify
   that you are serving files from the webroot path you provided.

And when I attempt to manually renew via sudo /usr/bin/letsencrypt renew I get that same error referring to SERVFAIL and the CAA.

After some investigating I’ve confirmed some things. My domain was registered through Google Domains, pointed to the digitalocean name servers, and I have an A record setup for my droplet. I’ve read that there are new requirements for issuing SSLs and renewals, specifically a CAA record, and that digitalocean doesn’t yet support this? According to this thread.

My question is is there anything I can do resolve this or must I wait until digitalocean supports CAA records? Am I forced to run the site unsecured for now?

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Matt Nordhoff

September 3, 2017

Accepted Answer

It’s hard to tell you anything without more information.

Let’s Encrypt does not require that you use CAA, only that your nameservers respond in a valid manner, which is an extremely low bar that most DNS providers meet (at least by now).

https://letsencrypt.org/docs/caa/

What’s your domain?

(Domains are public, and all Let’s Encrypt certificates are logged publicly.)