DevOps Engineer Containerizes Node.js App into 3-Tier Architecture on AWS ECR

A Cloud and DevOps Engineer containerized an Infrastructure Asset Tracker application using Docker, building a 3-tier architecture comprising a Node.js REST API backend, MongoDB database, and a Mongo Express admin visualizer. Each service runs as an independent container communicating over an internal Docker network, following the one-concern-per-container principle to allow independent scaling and graceful failure. The setup used a Docker Compose file to orchestrate the services, with dependency ordering to prevent race conditions on startup and named volumes to ensure MongoDB data persistence across deployments. Key Dockerfile optimizations included using the lightweight node:18-alpine base image, leveraging Docker layer caching to speed up rebuilds, and a .dockerignore file to exclude node_modules and environment secrets. After resolving real-world debugging issues such as port collisions caused by ghost processes and Docker daemon connectivity errors, the final image was securely pushed to AWS Elastic Container Registry.