aws-lambda-python-alpha: uv support for lambda layer

[kuehno]

Describe the feature

uv support for PythonFunction was added last year:
Issue Reference

It would be great to also support uv when creating Lambda Layers as currently only requirements.txt, Pipfile or poetry.lock are supported.
Which is kind of inconvenient to have both requirements.txt and pyproject.toml in the project.

Use Case

Manage python modules by uv, and deploy it to AWS Lambda Layer.

Proposed Solution

The uv can generate requirements.txt by running uv pip compile.

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)

2.206.0

AWS CDK CLI version

2.1022.0

Environment details (OS name and version, etc.)

Ubuntu 22.04 LTS

[pahud]

Hi @kuehno,

Thank you for this feature request! After investigating the codebase, I have some good news: uv support for PythonLayerVersion already exists and should work with your current setup.

The Packaging class already detects uv.lock files and the Bundling logic handles uv installations for both PythonFunction and PythonLayerVersion since they share the same bundling infrastructure.

Could you please test this with your actual project and let us know if it works? If you encounter any issues, please share the error messages.

The main gap appears to be in our documentation - the README mentions uv support for functions but not explicitly for layers. We should update the documentation to clarify that PythonLayerVersion supports the same dependency management options as PythonFunction:

• requirements.txt
• Pipfile/Pipfile.lock
• poetry.lock with pyproject.toml
• uv.lock with pyproject.toml ✅

Document Evidence

• PythonLayerVersion source - Uses same ·Bundling.bundle()· method
• Packaging source - Already includes uv detection
• Bundling source - Already handles uv installation
• README - Documents uv support for functions but not layers

---

If you confirm this works, we can close this as a documentation issue. If it doesn't work as expected, we'll investigate further as a bug.

Thanks for bringing this to our attention, and we'd love to hear about your experience with uv + CDK! 🚀

[github-actions]

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[kuehno]

Hi @pahud,

Thank you for your fast response. I initially tried to deploy the lambda layer using the uv.lock and pyproject.toml but it wont actually pick up the dependencies of my project.

This is how I am defining the layer:

My the "src" directory looks as follows:

Am I missing something here? When placing a requirements.txt file in the same directory it will install all requirements as usual.

(During deployment I will remove the .venv before actually deploying the stack to not dump it into the package accidentially.)

[related-issues-bot-for-aws]

Hi @kuehno,

Thanks for opening this issue! After reviewing the details, we found some other discussions that may be closely related:

Related Issues

• aws-lambda-python-alpha: Support uv #31238: This issue requested the initial uv support for Python dependency management in the aws-lambda-python-alpha module, which was implemented for PythonFunction. The current issue builds upon this by specifically requesting uv support for Lambda Layers, as the existing implementation doesn't fully work when creating Lambda Layers with uv.lock and pyproject.toml files. Both address the same goal of managing Python modules with uv for AWS deployments, but with different targets.

• aws-lambda-python-alpha: Support uv lockfile for PythonFunction bundling #32413: This issue specifically requested uv.lock file support for PythonFunction bundling, while the current issue focuses on extending that support to Lambda Layers. Both address the need for modern Python dependency management using uv in aws-lambda-python-alpha, but for different constructs. The current issue demonstrates that despite sharing bundling infrastructure, the Lambda Layer implementation has gaps that prevent proper detection and installation of dependencies from uv.lock files.

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