How I Built a Terraform AWS 3-Tier Platform — Modules, VPC, and Least-Privilege Security Groups

I recently built a complete AWS 3-tier infrastructure using Terraform —

fully modular, no console clicks, reproducible from a single terraform apply.

Here's the architecture, the key decisions, and what I learned.

Why 3-Tier?

Separating infrastructure into tiers isn't just good architecture theory —