Designing a Reliable File Processing Pipeline on AWS for Real-World Applications

Executive Summary This article presents the design and implementation of a resilient, event-driven file processing pipeline built using AWS serverless services. The solution leverages Amazon S3, AWS Lambda, Amazon SQS, DynamoDB, and a Dead Letter Queue (DLQ) to ensure scalability, fault tolerance, and operational reliability. The system was not only implemented but also validated through real-world testing scenarios, including successful file processing, duplicate handling using idempotency logic, IAM permission troubleshooting, and controlled failure simulation to verify retry and DLQ behavior. The result is a production-ready serverless architecture designed not just to function, but to remain stable under failure conditions. Introduction: Why File Processing Is Harder Than It Looks File uploads sound simple. A user uploads a CSV. The system reads it. The data gets stored. But in production systems, file ingestion is rarely that straightforward. What happens if: • The file is uploade