# Building a Production-Ready AWS VPC with Terraform: Multi-Tier Subnets, NAT Gateways, and VPC Endpoints

A network topology diagram showing a multi-tier VPC with public, private, database, cache, and management subnets across three availability zones, with NAT gateways and VPC endpoints illustrated. If you've ever inherited an AWS account where everything lives in the default VPC, you know the pain. Security groups used as the only network boundary. No flow logs. Public IP addresses on database instances. It's the kind of setup that keeps security teams awake at night. A well-architected VPC is the foundation of everything you build on AWS. Get it wrong, and you're retrofitting network isolation into a running production system — one of the least enjoyable exercises in cloud engineering. In this article, I'll walk through a production-grade VPC architecture using Terraform, based on a module I've been refining across multiple enterprise deployments. The full module is available at terraform-aws-vpc-complete . Why VPC Architecture Matters More Than You Think Most teams start with a simple