From Basic Terraform to Production IaC: Building an Auto-Scaling Azure Web App with Modular Terraform. Many engineers start learning Terraform by placing everything in a single  main.tf  file. While this approach works for learning syntax, it quickly breaks down in real environments. As infrastructure grows, single-file Terraform projects become difficult to maintain, hard to scale, and risky to change. Production environments demand more than “working code.” They require clarity, reusability, isolation of responsibilities, and predictable behavior during change. This is where the shift happens, from learning Terraform to engineering with Terraform.