Got error while parsing DNSName - invalid label

[kanton10062006]

What happened:
Spamming a lot of warnings in the logs about an invalid label

What you expected to happen:
Logs are clean

How to reproduce it (as minimally and precisely as possible):
It seems like it is trying to create a DNS name with more than one dash in a row...

Environment:

• External-DNS version (use external-dns --version): v0.20.0
• DNS provider: AWS Route 53
• Kubernetes version: v1.34.1-eks-3025e55
• Deployment method: https://kubernetes-sigs.github.io/external-dns chart
• Logs attached above

[kanton10062006]

Logs:

{"level":"warning","msg":"Got error while parsing DNSName ls---2431---live.placeholder.com: idna: invalid label \"ls---2431---live\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---2447---stage---test-partner.placeholder.com: idna: invalid label \"ls---2447---stage---test-partner\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---2447---stage.placeholder.com: idna: invalid label \"ls---2447---stage\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---3338---test-partner.placeholder.com: idna: invalid label \"ls---3338---test-partner\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---aepp-2098---branch-testing.placeholder.com: idna: invalid label \"ls---aepp-2098---branch-testing\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---coreinf-373---stage.placeholder.com: idna: invalid label \"ls---coreinf-373---stage\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---coreinf373---2.placeholder.com: idna: invalid label \"ls---coreinf373---2\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls---stage-retest-for-2338.placeholder.com: idna: invalid label \"ls---stage-retest-for-2338\"","time":"2025-11-26T11:33:42Z"}
{"level":"warning","msg":"Got error while parsing DNSName ls--test-partner-for-13480-st-connect.placeholder.com: idna: invalid label \"ls--test-partner-for-13480-st-connect\"","time":"2025-11-26T11:33:42Z"}
{"level":"info","msg":"All records are already up to date","time":"2025-11-26T11:34:44Z"}

Arguments:

        - '--log-level=info'
        - '--log-format=json'
        - '--interval=1m'
        - '--source=service'
        - '--source=ingress'
        - '--policy=sync'
        - '--registry=dynamodb'
        - '--provider=aws'
        - '--aws-zone-type=public'
        - '--dynamodb-region=us-west-1'
        - '--dynamodb-table=ciq-eks-external-dns-state'
        - '--exclude-record-types=AAAA'
        - '--txt-owner-id=sandbox.eks'
        - '--zone-id-filter=***********'

[vflaux]

Do the DNSName entries shown in the log match the actual DNS records you expect?
This warning occurs because the names are not valid according to rfc5891 section 5.4 (IDNA: protocol):

[...]
Putative U-labels with any of the following characteristics MUST be rejected prior to DNS lookup:
[...]
- Labels containing "--" (two consecutive hyphens) in the third and fourth character positions.

@ivankatliarchuk do we actually need the label validation with the idna.Profile when normalizing?

external-dns/internal/idna/idna.go

Lines 24 to 28 in 0c39b6e

	Profile = idna.New(
	idna.MapForLookup(),
	idna.Transitional(true),
	idna.StrictDomainName(false),
	)

We could disable label validation (idna.ValidateLabels(false)) or just the hyphens validation (idna.CheckHyphens(false)).

[kanton10062006]

Yes, the actual DNS record does match the log entries, and we are OK with them. Before the upgrade external-dns(below version 0.18.0) created them without any problems/warnings.
I understand that such DNS records seem silly, but it is what it is...