(rds/docdb): fromDatabaseInstanceAttributes stringifies number tokens incorrectly

When using a number token (from a CfnParamater of type Number) to create a DatabaseInstance with fromDatabaseInstanceAttributes, the token renders as an invalid literal in the template.

Reproduction Steps

    const existingDatabaseUrl = new CfnParameter(this, 'ExistingDatabaseUrl', {
      default: '',
    }).valueAsString;
    const existingDatabasePort = new CfnParameter(this, 'ExistingDatabasePort', {
      type: 'Number',
      default: 5432,
    }).valueAsNumber;
    const existingInstanceId = new CfnParameter(this, 'ExistingInstanceId', {
      default: '',
    }).valueAsString;

    const existingDatabaseInstance = DatabaseInstance.fromDatabaseInstanceAttributes(this, 'ExistingDatabaseInstance', {
      instanceIdentifier: existingInstanceId,
      securityGroups: [],
      instanceEndpointAddress: existingDatabaseUrl,
      port: existingDatabasePort,
    });

  new CfnOutput(scope, `DatabaseUrlOutput`, {
    exportName: 'databaseUrl',
    value: `${existingDatabaseInstance.dbInstanceEndpointAddress}:${existingDatabaseInstance.dbInstanceEndpointPort}`,
  });

What did you expect to happen?

The synthesized template for the output would create a Ref for the value

What actually happened?

  DatabaseUrlOutput:
    Value:
      Fn::Join:
        - ""
        - - Ref: ExistingDatabaseUrl
          - :-1.888154589708849e+289
    Export:
      Name: databaseUrl

Environment

• CDK CLI Version : 1.75.0 (build 7708242)
• Framework Version: 1.75.0
• Node.js Version: v12.16.2
• OS : OS X 10.14.6
• Language (Version): TypeScript 3.9.7

Other

Explicitly using Fn.join in the Output value causes a similar result:

  new CfnOutput(scope, `${idPrefix}DatabaseUrlOutput`, {
    exportName: 'databaseUrl',
    value: Fn.join(':', [instance.dbInstanceEndpointAddress, instance.dbInstanceEndpointPort]),
    // value: `${instance.dbInstanceEndpointAddress}:${instance.dbInstanceEndpointPort}`,
  });

synthesizes:

  ExistingDatabaseUrlOutput:
    Value:
      Fn::Join:
        - ":"
        - - Ref: ExistingDatabaseUrl
          - "-1.888154589708849e+289"
    Export:
      Name: databaseUrl

It looks like valueAsNumber is not returning a token, but instead a literal.

If I tell CDK to log that value after creating it, I see -1.888154589708849e+289 instead of something like ${Token[TOKEN.456]}

Related to https://github.com/aws/aws-cdk/issues/3448 and https://github.com/aws/aws-cdk/issues/10228 and https://github.com/aws/aws-cdk/issues/7126 and https://github.com/aws/aws-cdk/issues/9413?

The workaround for https://github.com/aws/aws-cdk/issues/9413 doesn’t apply for something like a DB Instance port because there’s no analog to Schedule.expression

---

This is 🐛 Bug Report

[skinny85]

That would be helpful @john-kontralto !

[github-actions[bot]]

⚠️COMMENT VISIBILITY WARNING⚠️

Comments on closed issues are hard for our team to see. If you need more assistance, please either tag a team member or open a new issue that references this one. If you wish to keep having a conversation with other community members under this issue feel free to do so.