feat: Become IDNA aware in Plan and DomainFilter

[kimsondrup]

Description

Ensure support for Internationalized Domain Names for Applications (aka. domains using Unicode) using golang.org/x/net/idna

Disclaimer, this is my first Go code so please look at it with extra skepticism

This PR replaces #4689 as I no longer have access to the neticdk organization

Checklist

• Unit tests updated
• End user documentation updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: kimsondrup / name: Kim Sondrup (98c3ecb, 3d48384)

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @kimsondrup. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[ivankatliarchuk]

You may need to do

if err != nil {
    log.Warnf(`Got error while parsing domain %s: %v`, domain, err)
     return domain
}

[ivankatliarchuk]

/label tide/merge-method-squash

[mloiseleur]

/ok-to-test

[k8s-ci-robot]

PR needs rebase.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[ivankatliarchuk]

fixes #5090

[mloiseleur]

@kimsondrup Do you think you can address review comments and rebase this PR ?

[lexisother]

Hi all,
My issue (#5090) was linked to this PR by @ivankatliarchuk, and I was hoping it'd fix it, but after having built my own Docker image off @kimsondrup's branch and using it in a deployment to my cluster, it still displays the exact same message I was hoping not to see:

DEBU[0003] no zoneIDFilter configured, looking at all zones
DEBU[0004] Skipping record a.xn--ccka2b6azt.xn--q9jyb4c because no hosted zone matching record DNS Name was detected
DEBU[0004] Skipping record a.a.xn--ccka2b6azt.xn--q9jyb4c because no hosted zone matching record DNS Name was detected

My ingress config can be found in my original issue, but I believe this PR to not fix the issue I described. Also, I've got a txtPrefix of %{record_type}. so that's why it shows a.a. in the second message.

[ivankatliarchuk]

Worth to submit a soluiton, if this PR is not going to resolve it

[lexisother]

I'm just providing whatever context I have, if I had a solution I'd have submitted a PR instead of an issue.
I've got a tiny bit more info, namely that Cloudflare (in my case) returns the zone name as "アリクシア.みんな", whereas external-dns likely tries finding the zone by xn--ccka2b6azt.xn--q9jyb4c, which obviously then doesn't match anything.

I hope this is enough to help someone make the necessary adjustments. I'll keep poking at it myself as well.

[lexisother]

I managed to resolve the problem!

time="2025-03-04T00:57:46Z" level=info msg="Changing record." action=CREATE record=a.xn--ccka2b6azt.xn--q9jyb4c ttl=1 type=A zone=49619bc8e3ea12578435348ffa4707f1
time="2025-03-04T00:57:46Z" level=info msg="Changing record." action=CREATE record=a.a.xn--ccka2b6azt.xn--q9jyb4c ttl=1 type=TXT zone=49619bc8e3ea12578435348ffa4707f1

Horrible hack, but this works for me. Up to you folks if this is a "good" fix or not, but I'd wager it breaks things unrelated to my specific usecase.
Here's the changes to provider/zonefinder.go:

func (z ZoneIDName) FindZone(hostname string) (suitableZoneID, suitableZoneName string) {
+ 	name, err := idna.Lookup.ToUnicode(hostname)
+ 	if err != nil {
+ 		name = hostname
+ 	}
	for zoneID, zoneName := range z {
- 		if hostname == zoneName || strings.HasSuffix(hostname, "."+zoneName) {
+		if name == zoneName || strings.HasSuffix(name, "."+zoneName) {
			if suitableZoneName == "" || len(zoneName) > len(suitableZoneName) {
				suitableZoneID = zoneID
				suitableZoneName = zoneName
			}
		}
	}
	return
}