Represent AWS Alias records as record type A

[johngmyers]

Description

Causes AWS Alias records to be represented in the planner as records of type A.

This resolves a conflicting interaction between #3747 (which resolves conflicts between CNAME records and records of any other type with the same domain) and #3605 (which gives the planner both CNAME and AAAA records for AWS aliases).

Checklist

• Unit tests updated
• End user documentation updated

[mloiseleur]

@johngmyers I understand there is an issue by representing Alias record with CNAME in the plan.

I'm unsure that switching to Type A will really fix it 🤔

Those kind of lines is quite confusing, for instance:

if isAlias, found := r.GetProviderSpecificProperty("alias"); found && isAlias == "true" && recordType == endpoint.RecordTypeA {
		recordType = endpoint.RecordTypeCNAME
	}

I understand that Alias is a (proprietary) extension, not part of current standard, but there is more than one provider implementing this specific record type.

=> Wdyt about adding a new Alias record type in the plan ?

[johngmyers]

With #3605 we will need two alias records for a domain, one A and one AAAA. This is because Route53 requires the two records in order for the alias to be dual-stack.

For backwards compatibility, the new-format TXT registry ownership record for an A alias record needs to be formatted as if it were a CNAME.

[johngmyers]

And Route53 is the only provider that uses the "alias" ProviderSpecificProperty.

[johngmyers]

Wdyt about adding a new Alias record type in the plan ?

That might help other providers, but doesn't help Route53. In Route53, alias records have an underlying type of A, AAAA, etc. and there has to be one alias record per type that is aliased. I wouldn't say Route53 has a good design, but it is what it is.

[mloiseleur]

/lgtm

[johngmyers]

/approve

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[johngmyers]

/retest