Bash script for quick Python based AWS Lambda Function Packaging

README.md

AWS Python Lambda Function Packaging

The script will create a ZIP file according to the AWS Documented process.

The resulting ZIP file can then be uploaded to S3 from where you can create the Lambda function, either by the AWS CLI, the AWS Console or by AWS CloudFormation. Just supply the S3 ZIP file URL and your Lambda function will be created.

Basic Workflow

1. Create a directory for your Python script (Lambda function) and create the initial script. If you need additional packages, specify then in a requirements.txt file in the same directory as the Python script
2. Code... coffee... code... coffee... etc. (repeat as required)
3. When you are done and need a ZIP file, run the packaging script. Each time you run it, a new package directory and ZIP file will be created.

Usually, boto3 will already be included in the Python Lambda environment, so no need to specify it in the requirements.txt file.

package_lambda_function.sh

#!/usr/bin/env bash

help_message () {
    script_name=${0##*/}
    echo "Usage: ${script_name} -f STRING -p STRING [-h]"
    echo
    echo "  -f STRING   - Path to the Python script to package as AWS Lambda function"
    echo "  -p STRING   - Package name (without any extensions)"
    echo "  -h          - Display help"
    echo
    exit
}

display_help=0
pyhton_script_path=""
package_name="python_lambda_function"

while getopts hf:p: flag
do
    case "${flag}" in
        h) display_help=1;;
        f) pyhton_script_path=${OPTARG};;
        p) package_name=${OPTARG};;
    esac
done

if [ "$display_help" -gt "0" ]; then
    help_message
fi

if [ -z "$pyhton_script_path" ]
then
      echo "ERROR: When supplying the -f parameter, a STRING value must be provided. Use the -h parameter for help."
      exit
fi

if ! test -f $pyhton_script_path; then
  echo "ERROR: File does not exist."
  exit
fi

echo "Starting to package AWS Lamda Function (Python)"

package_dir="/tmp/package_`cat /proc/sys/kernel/random/uuid | sed 's/[-]//g'`"

echo "  Creating temporary packaging directory: ${package_dir}"
mkdir -p $package_dir

echo "  Copy Python lambda function to package directory"
cp $pyhton_script_path $package_dir

requirements_file="`dirname ${pyhton_script_path}`/requirements.txt"
echo "  Checking for the presence of requirements.txt in the same directory as the script: ${requirements_file}"
if test -f $requirements_file; then
    echo "    Adding requirements..."
    cp $requirements_file $package_dir

    echo "    Creating Python virtual environment"
    cd $package_dir
    python3 -m venv venv
    . venv/bin/activate

    echo "    Adding required packages"
    mkdir package
    pip3 install --target ./package -r requirements.txt
    cd package
    zip -r ../${package_name}.zip .

    cd ..
    zip ${package_name}.zip `basename ${pyhton_script_path}`
else
    cd $package_dir
    zip ${package_name}.zip `basename ${pyhton_script_path}`
fi

echo "DONE"
echo
echo "  Package Directory : ${package_dir}"
echo "  Pakage File       : ${package_dir}/${package_name}.zip"
echo