Migrating to a different --txt-prefix

[mattburgess]

Hi there!

We have external-dns configured with a --txt-prefix of registry-. With the new-format registry records, we end up with a prefix of registry-cname which obviously eats into a lot of the 63-character limit as warned about here.

There's also this warning in the docs:

The prefix or suffix may not be changed after initial deployment, lest the registry records be orphaned and the metadata be lost.

But, I really want to shorten (remove!) the prefix. What I was considering was creating the new format/new prefix records ahead of time so that external-dns doesn't lose track of things. Would that work?

e.g. I currently have these records:

Name	TYPE	Value	Description
registry-myhost.example.com.	TXT	"heritage=external-dns,external-dns/owner..."	old format - can be deleted at any point
registry-cname-myhost.example.com.	TXT	"heritage=external-dns,external-dns/owner... "	new format - will remain until prefix-less record migration has completed
myhost.example.com.	CNAME

What I want:

Name	TYPE	Value	Description
cname-myhost.example.com.	TXT	"heritage=external-dns,external-dns/owner... "	new format with no --txt-prefix specified
myhost.example.com.	CNAME

So, I think that if I create that record ahead of redeploying external-dns without the --txt-prefix argument then once I do redeploy external-dns then it'll correctly continue to manage all of the records it currently is. I can then go ahead and safely delete all of the prefixed records.

Is my understanding correct?

Thanks!

PS: I've just noticed this note:

If using a txt registry and attempting to use a CNAME the --txt-prefix must be set to avoid conflicts.

Is that still right? With the new format behaviour of creating TXT records with a %{record_type}- prefix then I think conflicts are going to be avoided by default, right? Or do I still need to specify something short like --txt-prefix=reg-?