dehydrated/docs/dns-verification.md

dns-01 challenge

This script also supports the new dns-01-type verification. This type of verification requires you to be able to create a specific TXT DNS record for each hostname included in the certificate.

You need a hook script that deploys the challenge to your DNS server.

The hook script (indicated in the config file or the --hook/-k command line argument) gets four arguments:

$1 an operation name (clean_challenge, deploy_challenge, deploy_cert, invalid_challenge or request_failure) and some operands for that. For deploy_challenge

$2 is the domain name for which the certificate is required,

$3 is a "challenge token" (which is not needed for dns-01), and

$4 is a token which needs to be inserted in a TXT record for the domain.

Typically, you will need to split the subdomain name in two, the subdomain name and the domain name separately. For example, for "my.example.com", you'll need "my" and "example.com" separately. You then have to prefix "_acme-challenge." before the subdomain name, as in "_acme-challenge.my" and set a TXT record for that on the domain (e.g. "example.com") which has the value supplied in $4

_acme-challenge    IN    TXT    $4
_acme-challenge.my IN    TXT    $4

That could be done manually (as most providers don't have a DNS API), by having your hook script echo $1, $2 and $4 and then wait (read -s -r -e < /dev/tty) - give it a little time to get into their DNS system. Usually providers give you a boxes to put "_acme-challenge.my" and the token value in, and a dropdown to choose the record type, TXT.

Or when you do have a DNS API, pass the details accordingly to achieve the same thing.

You can delete the TXT record when called with operation clean_challenge, when $2 is also the domain name.

Here are some examples: Examples for DNS-01 hooks

dns-persist-01 challenge

This script also supports the dns-persist-01-type verification. This type of verification requires you to create a persistent TXT DNS record containing your Let's Encrypt account information.

Unlike dns-01, which requires dynamic DNS record updates for each certificate request, dns-persist-01 uses a single persistent record that remains in place indefinitely.

You need to create a TXT record named _validation-persist in the domain for which you want to request certificates. The record should contain your account URI and other metadata.

Example record:

_validation-persist.example.com. IN TXT (
  "letsencrypt.org;"
  " accounturi=https://acme-v02.api.letsencrypt.org/acme/acct/1234567890;"
  " policy=wildcard"
)

The account URI can be obtained by running dehydrated --register --accept-terms and checking the account registration response, or by examining the accounts/*/registration.json file after registration.

This record should be set up once and left in place. No hook script is required for dns-persist-01 as dehydrated does not perform any dynamic DNS updates for this challenge type.