aws_rds: missing AuroraPostgresEngineVersion.VER_16_9

[AkitoAndo]

Describe the bug

aurora supports postgresql 16.9 but the 16.9 constant is missing from AuroraPostgresEngineVersion

Regression Issue

• Select this option if this issue appears to be a regression.

Last Known Working CDK Library Version

No response

Expected Behavior

that constant should be present

Current Behavior

the constant is not defined

Reproduction Steps

> const { AuroraPostgresEngineVersion } = await import("aws-cdk-lib/aws-rds")
> AuroraPostgresEngineVersion.VER_16_9
undefined

Possible Solution

No response

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

2.201.0

AWS CDK CLI version

2.1003.0 (build b242c23)

Node.js Version

v20.18.1

OS

macos

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

Hi @AkitoAndo

Thank you for reporting this issue! You've identified a legitimate gap in the CDK's Aurora PostgreSQL engine version constants.

Issue Validation

I've confirmed that PostgreSQL 16.9 is indeed supported by Aurora according to the official AWS documentation. The Aurora PostgreSQL release calendar shows:

• Community release date: 8 May 2025
• Aurora release date: 30 June 2025
• Aurora end of standard support date: December 2026

However, the CDK's AuroraPostgresEngineVersion class is missing the VER_16_9 constant, which
explains why it returns undefined in your reproduction.

Root Cause

Looking at the source code in cluster-engine.ts, the class includes versions like VER_16_1, VER_16_2, VER_16_3, VER_16_4, VER_16_6, and VER_16_8, but VER_16_9 is missing. This appears to be a
maintenance oversight rather than an intentional omission.

Proposed Fix

The fix is straightforward - adding the missing constant following the established pattern:

public static readonly VER_16_9 = AuroraPostgresEngineVersion.of('16.9', '16', { s3Import: true, s3Export: true });

This should be added to the AuroraPostgresEngineVersion class alongside the other PostgreSQL
16.x versions.

Workaround Solution

Instead of using the missing AuroraPostgresEngineVersion.VER_16_9 constant, you can use the of() method to specify PostgreSQL 16.9 directly:

import { AuroraPostgresEngineVersion } from 'aws-cdk-lib/aws-rds';

// Instead of this (which returns undefined):
// const engine = AuroraPostgresEngineVersion.VER_16_9;

// Use this workaround:
const engine = AuroraPostgresEngineVersion.of('16.9', '16', {
  s3Import: true,
  s3Export: true
});

Contributing

Would you be interested in submitting a pull request for this fix? The change is minimal and follows a clear pattern. If you'd like to contribute, the [CDK Contributing Guide](https://
github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) has all the details you need to get started.

Thanks again for the detailed reproduction and for helping improve the CDK! 🚀