Shipment Management Application with Lambda Image Processing

Key	Value
Environment	LocalStack, AWS
Services	S3, Lambda, DynamoDB, SNS, SQS
Integrations	Terraform, AWS SDK, Spring Boot, React, Testcontainers
Categories	Serverless, Storage, Messaging
Level	Intermediate
Use Case	IaC Testing, AWS Parity
GitHub	Repository link

Introduction

This sample demonstrates a full-stack shipment management application that showcases integration between multiple AWS services. The application consists of a Spring Boot backend with a React frontend, implementing CRUD operations on shipments with Lambda image processing capabilities. To test this application sample, we will demonstrate how you use LocalStack to deploy the infrastructure on your developer machine and run the application locally. The demo highlights the ease of switching from actual AWS dependencies to LocalStack emulation for development environments without any code changes.

Architecture

The following diagram shows the architecture that this sample application builds and deploys:

• S3 for storing shipment pictures and Lambda deployment packages.
• Lambda function that validates uploaded pictures, applies watermarks, and replaces non-compliant files.
• DynamoDB table to store shipment entities with enhanced client mapping.
• SNS topic that receives update notifications from the Lambda function.
• SQS queue that subscribes to the SNS topic and delivers messages to the Spring Boot application.

Prerequisites

• localstack CLI with a LOCALSTACK_AUTH_TOKEN.
• AWS CLI with the awslocal wrapper.
• Terraform with the tflocal wrapper.
• Maven 3.8.5+ & Java 17
• Node.js & npm
• make (optional, but recommended for running the sample application)

Installation

To run the sample application, you need to install the required dependencies.

First, clone the repository:

git clone https://github.com/localstack-samples/sample-shipment-list-demo-lambda-dynamodb-s3.git

Then, navigate to the project directory:

cd sample-shipment-list-demo-lambda-dynamodb-s3

Next, install the project dependencies by running the following command:

make install

This will:

• Build the Lambda validator JAR file
• Install frontend dependencies via npm

Deployment

Start LocalStack with the LOCALSTACK_AUTH_TOKEN pre-configured:

localstack auth set-token <your-auth-token>
localstack start

To deploy the sample application, run the following command:

make deploy

The deployment will create:

• S3 buckets for shipment pictures and Lambda code
• DynamoDB table pre-populated with sample shipments
• Lambda function for image validation and processing
• SNS topic and SQS queue for messaging
• All necessary IAM roles and permissions

Testing

The sample application provides both automated tests and interactive usage through the web interface.

Start the React frontend:

cd shipment-list-frontend
npm start

The frontend will be available at http://localhost:3000.

Start the Spring Boot backend:

mvn spring-boot:run -Dspring-boot.run.profiles=dev

The backend will be available at http://localhost:8081.

You can run full end-to-end integration tests using the following command:

make test

Using the Application

Once both frontend and backend are running:

1. Visit http://localhost:3000 to see the shipment list
2. Upload images to shipments using the web interface
3. Valid images will be processed and watermarked by the Lambda function
4. Invalid files will be rejected and replaced with a placeholder
5. Real-time updates are delivered via Server-Sent Events when image processing completes

Available actions:

• Upload new images to existing shipments
• Delete shipments from the list
• View processed images with watermarks
• Create and update shipments via API endpoints

Use Cases

IaC Testing

This sample demonstrates Infrastructure as Code (IaC) testing by using identical Terraform configurations for both AWS and LocalStack environments. The application leverages Spring profiles to seamlessly switch between production and development configurations without code changes.

The Terraform configuration defines all necessary AWS resources and their relationships, while tflocal automatically reconfigures endpoints for LocalStack. This approach enables:

• Validation of infrastructure changes before AWS deployment
• Consistent development environments across teams
• Faster iteration cycles during development
• Cost-effective testing of AWS integrations

AWS Parity

The sample showcases LocalStack's AWS parity by demonstrating identical behavior between LocalStack and AWS environments:

• S3 trigger configurations work identically in both environments
• Lambda function execution and environment variable handling
• DynamoDB enhanced client operations and table management
• SNS/SQS messaging patterns and subscription handling
• IAM role and policy enforcement

The application uses Spring Boot profiles (dev for LocalStack, prod for AWS) with different endpoint configurations (application-prod.yml, application-dev.yml), ensuring the same codebase works across both environments. Testcontainers integration provides additional validation that the LocalStack environment accurately emulates AWS behavior.

Summary

This sample application demonstrates how to build, test, and deploy a full-stack serverless application using AWS services and LocalStack. It showcases the following patterns:

• Defining and deploying S3, Lambda, DynamoDB, SNS, and SQS resources using Terraform.
• Building a Lambda function for automated image processing with watermarking capabilities.
• Integrating multiple AWS services in a Spring Boot application with reactive messaging.
• Using Spring Boot profiles to seamlessly switch between LocalStack and AWS environments.
• Implementing real-time updates using Server-Sent Events and SQS message consumption.
• Leveraging Testcontainers for integration testing against LocalStack infrastructure.
• Utilizing tflocal and awslocal to streamline local development workflows.

Learn More

• Smooth transition from AWS to LocalStack for your DEV environment (recommended)
• LocalStack and AWS Parity explained
• Using AWS SDKs with LocalStack
• Deploying Terraform with LocalStack
• Testcontainers with LocalStack