aws-ecs: missing `scaleInAfter` property in `ManagedInstancesCapacityProvider`

[garysassano]

Describe the feature

AWS recenty introduced the scaleInAfter property for ECS Managed Instances, but that's not currently supported in the ManagedInstancesCapacityProvider L2 construct.

AWS News: Amazon ECS Managed Instances adds configurable scale-in delay

Use Case

Support latest ECS features.

Proposed Solution

No response

Other Information

No response

Acknowledgements

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

AWS CDK Library version (aws-cdk-lib)

2.223.0

AWS CDK CLI version

2.1031.2

Environment details (OS name and version, etc.)

Ubuntu 24.04

[pahud]

Hi @garysassano,

Thank you for bringing this to our attention! You're correct that the scaleInAfter property from the recently announced configurable scale-in delay feature is not yet available in the ManagedInstancesCapacityProvider L2 construct.

This appears to be a valid feature request. The property exists in the CloudFormation specification under the InfrastructureOptimization configuration but hasn't been exposed in the CDK L2 construct yet.

The implementation would involve:

1. Adding a scaleInAfter?: Duration property to the ManagedInstancesCapacityProviderProps interface
2. Updating the capacity provider configuration in the ManagedInstancesCapacityProvider constructor to include the infrastructureOptimization property when scaleInAfter is specified

As a workaround until this is implemented, you could use an escape hatch to add this property directly to the L1 construct, though this would be less ergonomic than having native L2 support.

Would you be interested in contributing a PR for this feature? The change appears to be relatively straightforward and would be a great contribution to the CDK! If you need any guidance on the implementation, the team would be happy to help.

[sAchin-680]

Hi @pahud - thanks for the detailed clarification and guidance!

I'm interested in contributing this feature and would like to proceed with adding support for the scaleInAfter property to the ManagedInstancesCapacityProvider L2 construct.

My plan is:

• Add scaleInAfter?: Duration to ManagedInstancesCapacityProviderProps
• Extend the constructor to map this value into the CloudFormation InfrastructureOptimization block
• Add corresponding unit tests to validate both default behavior and the case when the field is explicitly set
• Include a jsii example if appropriate

Could you please assign the issue to me?

[sAchin-680]

Also before I start working on the PR, just confirming:

1. Should the property be strictly Duration, or would you prefer a number in seconds?
2. Any naming preference: scaleInAfter vs scaleInDelay or align strictly with the CloudFormation naming?

Once confirmed, I’ll begin implementation.

Thanks again ! Looking forward to contributing this!