(cli): hot-swap Lambda Layers attached to functions

[misterjoshua]

Description

I'd like the CDK CLI to support hot-swapping Lambda layers and associated lambda functions.

Use Case

I'm developing a Lambda Extension in a Lambda Layer while the Layer is attached to a Lambda function. Whenever I hit save in CDK watch mode, the CDK CLI uses CloudFormation to deploy the changes and takes 90-100 seconds every time.

Proposed Solution

I'm not familiar with the hot-swap code, but I think you could create a new layer version with the uploaded asset and update the functions it's attached to.

Other information

No response

Acknowledge

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

[rix0rrr]

@skinny85 @comcalvi did we add support for this already?

[skinny85]

We did not, actually 🙂.

[twixr]

Would love to see this as well.
My codebase consist of a lot of Lambda functions with shared code in layers.
If I change a simple line of code in a layer, it will take almost 200 seconds, since it performs a full deployment.
While only updating a Lambda will take several seconds.

[kjones]

My codebase consist of a lot of Lambda functions with shared code in layers.

My exact use case also. Multiple Lambda Functions handling API requests or EventBridge events. Tiny entry points into a shared layer DDD core.

It does look like SAM CLI (sam sync) supports this. 🤔