This project demonstrates how to implement the Outbox Pattern to guarantee consistency between database writes and event emissions in a distributed microservices architecture. Leveraging AWS services, Terraform infrastructure-as-code, and LocalStack for local testing, this setup ensures reliable, event-driven communication.

You can check technical blog here : How to Build an Event-Driven Outbox Pattern with AWS, Terraform and LocalStack

• Terraform
• LocalStack
• AWS CLI or awslocal CLI for LocalStack
• Python 3.12+ (for Lambda code)

• Two DynamoDB tables:
  • orders — main business data
  • orders.outbox — stores event records with DynamoDB Streams enabled
• Lambda function triggered by DynamoDB Stream on orders.outbox
• Lambda publishes events to an SQS FIFO queue

• Full infrastructure provisioning with Terraform
• AWS services emulated locally using LocalStack
• DynamoDB tables with streams for event tracking
• SQS FIFO queue for reliable message delivery
• Lambda functions to handle:
  • Writing orders and events (outbox-lambda)
  • Processing outbox events and sending to SQS (sync-event lambda)
• Robust error handling and retry logic in Lambda functions