feat: IDNA awareness in the zone finder

[lexisother]

Description

Normalise domain names before looking them up in the zone ID mapping.

Fixes #5090

Checklist

• Unit tests updated
• End user documentation updated

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[k8s-ci-robot]

Hi @lexisother. Thanks for your PR.

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[ivankatliarchuk]

/ok-to-test

[mloiseleur]

Is this really enough ? What about a warning log here to (at least) inform user of the error ?

[lexisother]

Sure, I'll add something. Is this okay?

log.Warnf("Failed to normalise '%s': %v", hostname, err)

[ivankatliarchuk]

Could we add test as well for that logging entry?

external-dns/internal/testutils/log.go

Line 36 in 4b2fd49

func LogsToBuffer(level log.Level, t *testing.T) *bytes.Buffer {

. you could find example usages in code

[mloiseleur]

normalise is not that clear. Wdyt about this :

log.Warnf("Failed to convert hostname '%s' to its Unicode form: %v", hostname, err)

[lexisother]

Looks good, I'll get to adding the warning and the respective test later today. 👍🏻

[ivankatliarchuk]

/label tide/merge-method-squash