package

Lambda layer packaging — Step 2 of the layer workflow.

This module provides two tool-agnostic functions that every downstream builder needs after dependencies have been installed:

  1. move_to_dir_python() — relocate installed packages into the python/ directory that AWS Lambda requires for layers.

  2. create_layer_zip_file() — compress that directory into a deployable layer.zip.

Why a separate ``python/`` directory?

AWS Lambda layers are extracted into /opt. For Python packages to be importable, they must live under /opt/python so that Python’s default sys.path picks them up. The zip must therefore contain python/ as its top-level entry — not a bare set of packages and not an absolute path.

Why ``temp_cwd`` before zipping?

The zip command records paths relative to the current working directory. By cd-ing into the artifacts directory first, the resulting zip entries start with python/… instead of the full host filesystem path.

aws_lbd_art_builder_core.layer.package.move_to_dir_python(dir_site_packages: Path, dir_python: Path)[source]

Relocate installed packages into the Lambda layer’s python/ directory.

Why this is needed: Different build tools place packages in different locations (e.g. .venv/lib/python3.x/site-packages/). Lambda layers require all packages under a single python/ directory so they appear on sys.path at runtime. This function bridges that gap by moving (not copying) the site-packages tree into the target.

Parameters:

  • dir_site_packages – Path to the source site-packages directory

  • dir_python – Path to the target python/ directory

Raises:

FileNotFoundError – If the source site-packages directory doesn’t exist

aws_lbd_art_builder_core.layer.package.default_ignore_package_list = ['boto3', 'botocore', 's3transfer', 'urllib3', 'setuptools', 'pip', 'wheel', 'twine', '_pytest', 'pytest']

Default packages to exclude from Lambda layer zip files.

  • AWS Runtime Provided: boto3, botocore, s3transfer, urllib3 are pre-installed in Lambda — bundling them wastes space and can cause version conflicts with the runtime.

  • Build Tools: setuptools, pip, wheel, twine are not needed at runtime.

  • Development Tools: pytest, _pytest are testing frameworks not needed in production.

aws_lbd_art_builder_core.layer.package.create_layer_zip_file(dir_python: Path, path_layer_zip: Path, ignore_package_list: list[str] | None = None, verbose: bool = True)[source]

Create optimized zip file for AWS Lambda layer deployment.

Compresses the python/ directory into a zip file with maximum compression (-9) and selective package exclusions.

Parameters:

  • dir_python – Path to the python/ directory containing layer packages

  • path_layer_zip – Output path for the layer zip file

  • ignore_package_list – Packages to exclude from the zip. If None, uses default_ignore_package_list.

  • verbose – If True, shows detailed zip creation progress