Create python lambda layer contents

create_lambda_layer.sh

#!/usr/bin/env bash
set -eu -o pipefail

# echo to stderr
eecho() { echo "$@" 1>&2; }

usage() {
  cat <<EOF
Usage:
  bash $(basename "$0") <python-version> <requirements-file>
Description:
  Create lambda layer zip file according to the requirements file.
Requirements:
  docker, jq
Arguments:
  python-version    : Python version
  requirements-file : Path of pip requirements file
EOF
}

# Check number of arguments
if [[ $# != 2 ]]; then
  usage && exit 1
fi

PYTHON_VERSION=$1
REQUIREMENTS_FILE=$2

if [[ ! -f ${REQUIREMENTS_FILE} ]]; then
  eecho "[ERROR] requirements file '${REQUIREMENTS_FILE}' not found."
  exit 1
fi

DEST_DIR=$(mktemp -d)

cp "${REQUIREMENTS_FILE}" "${DEST_DIR}"

(
  cd "${DEST_DIR}"
  mkdir python

  # Run pip install command inside the official python docker image
  docker run --rm -u "${UID}:${UID}" -v "${DEST_DIR}:/work" -w /work "python:${PYTHON_VERSION}" pip install -r "${REQUIREMENTS_FILE##*/}" -t ./python >&2

  # Remove unneeded files
  find python \( -name '__pycache__' -o -name '*.dist-info' \) -type d -print0 | xargs -0 rm -rf
  rm -rf python/bin

  # Return JSON for Terraform
  jq -n --arg path "${DEST_DIR}" '{"path":$path}'
)

example.tf

locals {
  layer_zip_path = "${path.root}/.terraform/tmp/my-lambda-layer.zip"
}

data "external" "lambda_layer" {
  program = ["./create_lambda_layer.sh", "3.9", "requirements.txt"]
}

data "archive_file" "lambda_layer" {
  type             = "zip"
  output_path      = local.layer_zip_path
  source_dir       = data.external.lambda_layer.result.path
  output_file_mode = "0644"
}

resource "aws_lambda_layer_version" "main" {
  layer_name          = "my-lambda"
  filename            = data.archive_file.lambda_layer.output_path
  compatible_runtimes = ["python3.9"]
  source_code_hash    = data.archive_file.lambda_layer.output_base64sha256
}