feat(rds): support for local write forwarding in an Aurora Mysql cluster

[badmintoncryer]

Issue # (if applicable)

Closes #31523 .

Reason for this change

Cloudformation supports enabling local write forwarding feature but AWS CDK does not support it.

Description of changes

• Add enableLocalWriteForwarding to DatabaseClusterBaseProps
• Add validation that engineType is either aurora or aurora-mysql
  • Having engineType set to aurora means launching a MySQL-compatible Aurora cluster.

Description of how you validated changes

Add both unit and integ tests.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[go-to-k]

Thanks for the PR. I made one very minor comment.

(And below is just my note)

I ran CFn to see if CFn really throws when enableLocalWriteForwarding is false and engine type is not mysql. Then I got an error even though it was false. In other words, the validation was correct :)

    if (props.enableLocalWriteForwarding !== undefined && !['aurora', 'aurora-mysql'].includes(props.engine.engineType)) {
      throw new Error(`\'enableLocalWriteForwarding\' is only supported for Aurora Mysql cluster engine type, got: ${props.engine.engineType}`);
    }

[badmintoncryer]

@go-to-k Thank you for your review!

Then I got an error even though it was false.

This result was also something I did not anticipate. The validation using !== undefined was not intended to account for this but happened by chance.

I added a case to the unit test to verify that an error occurs even when false is passed!

[go-to-k]

It might be good to add a code comment at the conditional branch that says that a CFn error will occur not only when the property is true but also when false, if the engine type is not mysql. Otherwise developers might get confused.

[badmintoncryer]

@go-to-k I have updated the description!

[go-to-k]

LGTM!

[sumupitchayan]

Thanks for your contribution!

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 8db1fef
• Result: SUCCEEDED
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[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

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