How to bundle your lambda with external dependencies by using BundlingOptions

Introduction

In this Post I'll explain you how to use the BundlingOptions Construct feature to bundle external dependencies.

How to use BundlingOptions

IMPORTANT

As a Pre Requisite we need to have installed Docker as PythonFunction uses it to bundle the dependencies.

Example of use case: We are trying to deploy a dummy lambda which uses the numpy

Create a new folder called 'lambda' this folder will contain two files. The requirements file which will contain the dependencies to be bundled alongside our lambdas/

requirements.txt

numpy==2.0.0

And the my_lambda.py an example of lambda using the library defined on our requirements.txt

my_lambda.py

import numpy as np

def handler(_event, _context):
    return np.random.randint(1, 10)

Now our folder should look like something like this

  lambda  -> requirements.txt
          -> my_lambda.py

And in on our Stack we can define our lambda by using PythonFunction

stack.py


from aws_cdk import BundlingOptions, Stack
from aws_cdk.aws_lambda import Code, Function, Runtime
from constructs import Construct
from os import path


class MyStackV2(Stack):
    def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
        super().__init__(scope, construct_id, **kwargs)

        Function(
            self,
            "AWSCdkDependenciesV2Lambda",
            code= Code.from_asset(path.join(path.dirname(__file__), "lambda"),
                bundling=BundlingOptions(
                    image= Runtime.PYTHON_3_12.bundling_image,
                    command=["bash", "-c", 
                             "pip install -r requirements.txt -t /asset-output && cp -r . /asset-output"
                    ]
                )
            ),
            runtime=Runtime.PYTHON_3_12,
            handler="my_lambda.handler"
        )

Docker will install the libraries of the requirements.txt and then bundle it to be uploaded alongside your lambda.

Thank you for reading it!