(neptune-alpha): Add PubliclyAccessible option to DatabaseCluster options

[dennis-ruhe-npo]

Describe the feature

Recently, AWS Neptune released v1.4.6.0 which includes a feature for instances to have a public IP assigned. This new feature is currently unavailable in CloudFormation and CDK.

https://docs.aws.amazon.com/neptune/latest/userguide/neptune-public-endpoints.html

Use Case

We currently use a convoluted setup with a Network Load Balancer to be able to access the cluster externally, while this option would make it very straightforward.

Proposed Solution

Add PubliclyAccessible as a L1 construct option and include support for it in the neptune-alpha package.

Other Information

The documentation does state that support is included in CloudFormation, however I am not able to find the relevant option and setting it with addPropertyOverride leads to an error (extraneous key [PubliclyAccessible] is not permitted).

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS CDK Library version (aws-cdk-lib)

2.218.0

AWS CDK CLI version

2.1029.3

Environment details (OS name and version, etc.)

N/A

[pahud]

Hi @dennis-ruhe-npo,

Thank you for this feature request! You're right that AWS Neptune v1.4.6.0 introduced support for public endpoints, which is a valuable feature for certain use cases.

The implementation of this feature in CDK requires two steps:

1. CloudFormation Support: First, the PubliclyAccessible property needs to be added to the AWS::Neptune::DBInstance CloudFormation resource specification. This is managed by the AWS CloudFormation service team and is auto-generated into the CDK.

   Important: I checked the CloudFormation coverage roadmap and there is no existing issue for Neptune's PubliclyAccessible property. You may want to create an issue there to track CloudFormation support.

2. CDK L2 Construct Support: Once CloudFormation support is available, we need to expose this property in the neptune-alpha package's L2 constructs:

   • Add publiclyAccessible to DatabaseInstanceProps
   • Add publiclyAccessible to DatabaseClusterProps
   • Update the DatabaseInstance constructor to pass this property to CfnDBInstance
   • Update the DatabaseCluster constructor to pass this property when creating instances

The error you encountered with addPropertyOverride suggests that CloudFormation may not yet recognize this property in the resource specification, even though it's documented. I recommend:

1. Verifying the CloudFormation documentation to confirm PubliclyAccessible is available for AWS::Neptune::DBInstance
2. If it's available in CloudFormation but not in CDK, this would be resolved by updating the CloudFormation specification in CDK
3. If you're interested in contributing, we'd welcome a PR once CloudFormation support is confirmed!

In the meantime, your NLB workaround is a reasonable approach for external access.

Would you be interested in contributing this feature once CloudFormation support is confirmed? We'd be happy to guide you through the contribution process!

[dennis-ruhe-npo]

Thank you for your reply. I have raised an issue at the CloudFormation repository aws-cloudformation/cloudformation-coverage-roadmap#2374