aws-cdk-lib: CustomResourceProvider does not allow .mjs ECMAScript modules

[bpauwels]

Describe the feature

When creating a CustomResourceProvider with NODEJS_20_X runtime and specifying a codeDirectory that contains an index.mjs file, the deployment fails. ("Error: cannot find codeDirectory/index.js").

Use Case

Since it is the default now to have an index.mjs ECMAScript module when you create a node 20.x Lambda Function in the AWS console, I would expect that this is possible for CDK Custom Resources as well.

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

CDK version used

2.151.0

Environment details (OS name and version, etc.)

MacOS Sonoma

[ashishdhingra]

The mentioned error is perhaps thrown here. The check should be modified probably to include .mjs file if the runtime is nodejs20.x.

Creating a Lambda function in AWS console targeting Nodejs 20.x runtime uses index.mjs file as shown below: