Serverless Image Resizer with LocalStack & Terraform

This is a simple example of how to use LocalStack to create a serverless image resizer using AWS Lambda and S3. The image resizer is implemented in Python and uses the Python Imaging Library (PIL) to resize images.

Requirements

• LocalStack with the localstack CLI.
• Terraform CLI with the tflocal wrapper.
• AWS CLI with the awslocal wrapper.
• A valid LocalStack for AWS license. Your license provides a LOCALSTACK_AUTH_TOKEN to activate LocalStack.

Start LocalStack

Start LocalStack Pro with the LOCALSTACK_AUTH_TOKEN pre-configured:

export LOCALSTACK_AUTH_TOKEN=<your-auth-token>
make start
make ready

Build the Lambda function

To build the Lambda function, you need to create a ZIP archive with the Python code and the required dependencies. You can use the following commands to create the ZIP archive:

docker run --platform linux/x86_64 --rm -v "$PWD":/var/task "public.ecr.aws/sam/build-python3.11" /bin/sh -c "pip3 install -r requirements.txt -t libs; exit"

cd libs && zip -r ../lambda.zip . && cd ..
zip lambda.zip lambda_function.py
rm -rf libs

Deploy the infrastructure

To run this example you need to execute:

tflocal init
tflocal plan
tflocal apply --auto-approve

After the Terraform script has been applied, you can upload an image to the S3 bucket and check the resized image in the resized folder. Here is an example:

awslocal s3 cp image.png s3://original-images/image.png
awslocal s3 ls s3://resized-images

Run the tests

You can run tests using the Terraform Test framework:

tflocal test