refactor: explicitly return at most one endpoint in generateTXTRecord

[bachorp]

What does it do ?

Changes generateTXTRecord to return exactly one endpoint or nil (in case of error) instead of a list of endpoints.

Motivation

This change will allow to keep TXT records generated for updateOld and updateNew aligned by construction. (Aligned meaning that updateOld[i] corresponds to updateNew[i].) Such alignment is not possible if generateTXTRecord returns an opaque list. See also #5681.

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

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[k8s-ci-robot]

Hi @bachorp. 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]

I have a strong feeling this will recreate the records. Is there any way you can prove on a real cluster that this won't happen?

[bachorp]

I have a strong feeling this will recreate the records. Is there any way you can prove on a real cluster that this won't happen?

Could you elaborate on that? I fail to see how such side effect would be possible. (Not to say that it shouldn't be tested, of course.)

[ivankatliarchuk]

The change could have some cascading effects on records. Unit tests at the moment do not cover all the scenarios.

[ivankatliarchuk]

/ok-to-test

[mloiseleur]

@bachorp We have enabled coveralls, so if you rebase this PR, you will see a comment on it with coverage information. There is also Makefile target to ease local run.

[bachorp]

Statements of changed functions not covered:

• txt.go#L185
• txt.go#L213
• txt.go#L229
• txt.go#L321

v1alpha1_ Go Coverage Report.html