(aws_cdk.aws_lambda_python_alpha): Allow creating of Command Hooks

[whatnick]

Describe the feature

Allow running pre-bundling install of extra dependencies in an image such as poetry-export-plugin required for Poetry 2+.

Use Case

Allow use of poetry 2+

Proposed Solution

Allow creation of the interface subclasses and serialization to typescipt.

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)

2.220.0

AWS CDK CLI version

2.1030.0

Environment details (OS name and version, etc.)

Linux Ubuntu 22.04

[pahud]

Hi @whatnick,

Thank you for this feature request! Based on my analysis, the functionality you're looking for appears to already exist through the commandHooks interface in the bundling options.

The bundling process executes commands in this order:

1. beforeBundling hooks
2. Poetry export command
3. afterBundling hooks

This means you should be able to install the poetry-export-plugin in the beforeBundling hook. Combined with setting the Poetry version via buildArgs (as discussed in #35790), this should enable Poetry 2+ support.

For TypeScript:

import * as lambda_python from '@aws-cdk/aws-lambda-python-alpha';

new lambda_python.PythonFunction(this, 'MyFunction', {
  entry: 'path/to/function',
  runtime: lambda.Runtime.PYTHON_3_11,
  bundling: {
    buildArgs: {
      POETRY_VERSION: '2.2.1',
    },
    commandHooks: {
      beforeBundling(inputDir: string, outputDir: string): string[] {
        return ['poetry self add poetry-export-plugin'];
      },
      afterBundling(inputDir: string, outputDir: string): string[] {
        return [];
      },
    },
  },
});

However, I notice you mentioned "serialization to typescript" which suggests you might be using the Python CDK bindings. Could you clarify:

1. Are you using TypeScript or Python CDK?
2. If Python, have you tried implementing the ICommandHooks interface from Python?
3. Are you encountering any specific errors when trying to use command hooks?

If the issue is that ICommandHooks isn't properly accessible from Python, that would be a valid concern that needs to be addressed in the JSII bindings. If it is accessible but not well documented, we should improve the documentation.

The README already documents command hooks for TypeScript, but Python examples would be valuable if this functionality works from Python.

Since you mentioned you may be able to implement this feature request, contributions are always welcome! Depending on what we discover:

• If it already works from Python: A PR adding Python examples to the documentation would be helpful
• If it doesn't work from Python: A PR to fix the JSII bindings would be appreciated

Looking forward to your feedback so we can determine the best path forward!

[whatnick]

I have implemented my own JSII binding and tested it from my code here : #32762 (comment) , could you please comment on something like this being suitable as a concrete implementation for upstream for reuse by others ?