#18880 Allow building AWS Lambda Layers Issue created by huonw Is your feature request related to a problem? Please describe. AWS Lambda has a concept of a layer, which is a (potentially) shared chunk of dependencies that are loaded into the environment, along with the main deploy package. This allows potential optimisations: • sharing common sets of dependencies across multiple lambdas • separating dependencies into a layer and source into the main deploy artefact: • faster builds: not having to wrangle potentially hundreds of megabytes of third party deps for a minor first-party source change that • more convenient iteration: the first party source artefact is likely to small enough (less than 3MB) to be viewed/edited in the AWS console for faster experimentation • putting large common dependencies (like boto3) into a single layer so that they're not needing to be duplicated into artefacts for individual lambdas (doing this useful would require pantsbuild/pex#2097 or similar, to ensure that the deps can be excluded from all other lambda packages) Describe the solution you'd like Create a new

python_awslambda_layer

target that uses

pex3 venv create --layout=flat-zipped --prefix=python ...

pantsbuild/pex#2140 (in 2.1.135) to export deps/src in the format expected: https://docs.aws.amazon.com/lambda/latest/dg/configuration-layers.html#configuration-layers-path Some questions/notes: • should this support parameters like

handler

at all? Or just require a user to specify

dependencies=["..."]

and `include_requirements`/`include_sources` as desired? I'm thinking just

dependencies

• It'd be good to allow

--layout=flat

to support #18282. Describe alternatives you've considered Reusing the

python_awslambda

target with a flag like

format="deployment" | "layer"

, which seems needlessly confusing. Additional context N/A pantsbuild/pants