aws-rds : Allow full support for scaling configuration options

[npvisual]

Describe the feature

Currently there are only 3 supported properties for ServerlessScalingOptions :

• auto_pause
• max_capacity
• min_capacity

However the CloudFormation template allows for 2 more options :

• SecondsBeforeTimeout
• TimeoutAction

Those allow for the configuration of the following behavior for an Aurora Serverless Cluster :

Force scaling the capacity to the specified values when the timeout is reached

This is an important configuration to control the impact that an auto-scaling event has on client applications.

Use Case

If a client application performs some long running queries / transactions against the Aurora Serverless Cluster then the server will never be able to auto-scale up / down as it will never find a scaling point. Also as pointed out in the Best practices for working with Amazon Aurora Serverless v1 doc, rolling back the auto-scaling transaction can take significant time.

So we should be able to provide the option to configure the Aurora Servless Cluster to forcefully up/down scale and let the application deal with that, if so desired.

Proposed Solution

Support the existing additional parameters that are currently available in the CloudFormation template for the AWS::RDS::DBCluster ScalingConfiguration property.

• SecondsBeforeTimeout
• TimeoutAction

This could also follow a similar behavior that is used currently for the auto_pause option : if the duration value is 0 then forceful auto-scaling is enabled, if not then it's the duration of the timeout before the rollback.

Other Information

AuroraPostgresEngineVersion VER_13_9

Acknowledgements

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

CDK version used

2.95.1 (build ae455d8)

Environment details (OS name and version, etc.)

macOS 13.5.2 ; Debian 3.11.4-slim-bookworm

[peterwoodworth]

Thanks for the request, you're right that these are not currently supported, and I think your proposed solution sounds fine. Thanks for the research on this!

Source code

aws-cdk/packages/aws-cdk-lib/aws-rds/lib/serverless-cluster.ts

Line 444 in 3edd240

private renderScalingConfiguration(options: ServerlessScalingOptions): CfnDBCluster.ScalingConfigurationProperty {

[edxlang]

Hi, I'd like to work on this.

[peterwoodworth]

go for it @0xedl 🙂