[Route53] HostedZone.hostedZoneNameServers property does not synthesize correctly

The synthesized template contains a CDK Token rather than a cloudformation Fn::GetAtt statement when referencing the hostedZoneNameServers property of a HostedZone construct.

Reproduction Steps

    const zone = new HostedZone(this, 'HostedZone', {
      zoneName: 'example.com',
    })

    const nameServer1 = zone.hostedZoneNameServers ? zone.hostedZoneNameServers[0] : 'UNDEFINED'

    new CfnOutput(this, 'ZoneId', { value: zone.hostedZoneId })
    new CfnOutput(this, 'NameServer1', { value: nameServer1 })

What did you expect to happen?

NameServer1 Cfn output in the template should consist of a Fn::GetAtt expression, not a CDK token.

What actually happened?

Synthesized template contains:

  "Outputs": {
    "HostedZoneId": {
      "Value": {
        "Ref": "HostedZoneDB99F866"
      }
    },
    "NameServer1": {
      "Value": "#{Token[TOKEN.93]}"
    }
  },

NOTE: Also expect this to work if zone.hostedZoneNameServers is used where an array is expected.

Environment

• CLI Version : 1.70.0
• Framework Version: 1.70.0
• Node.js Version: v14.2.0
• OS :MacOS Catalina 10.15.7
• Language (Version): typescript 4.0.3

Other

A public HostedZone will always have nameservers, a private zone will not. Perhaps change the semantics so that the zone.hostedZoneNameServers property is guaranteed to be defined in a public zone. This might make it easier to synthesize correctly?

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This is 🐛 Bug Report

[dio833]

I encountered a similar problem and found it here. @balkat solved my problem, thanks!

I just directly use hostedZoneNameServers property.

const nsArray = zone.hostedZoneNameServers as string[];
const nsList = cdk.Fn.join(',', nsArray );
new cdk.CfnOutput(this, 'NameServerList', { value: nsList });

[balkat]

And for completeness, I was able to deploy by adding extra code to join the array returned by GetAtt into a string:

    const zoneResource = zone.node.defaultChild as CfnResource
    const nsAttr = Fn.getAtt(zoneResource.logicalId, 'NameServers') as unknown
    const nsAttrArray = nsAttr as string[]
    const nsList = Fn.join(',', nsAttrArray)
    new CfnOutput(this, 'NameServerList', { value: nsList })

Synthed template:

  "Outputs": {
    "NameServerList": {
      "Value": {
        "Fn::Join": [
          ",",
          {
            "Fn::GetAtt": [
              "HostedZoneDB99F866",
              "NameServers"
            ]
          }
        ]
      }
    },

Output from cloudformation deployment:

HostedZone-Zone-cbutcher.NameServerList = ns-1056.awsdns-04.org,ns-153.awsdns-19.com,ns-1644.awsdns-13.co.uk,ns-990.awsdns-59.net