Infrastructure as Code (IaC) - Interview Guide

Infrastructure as Code means defining infrastructure through declarative configuration files rather than manual processes. This gives you version control, peer review, reproducibility, and automation. I primarily use Terraform with remote state in S3 and DynamoDB locking. I organize code into reusable modules — a VPC module, an ECS service module, a database module — each with its own tests. All changes go through PR review and plan output before apply. I also use Terragrunt for managing multiple environments with minimal duplication. In my current role, I migrated our entire AWS infrastructure from ClickOps to Terraform — 150+ resources across 3 environments. This reduced environment setup time from 2 days to 15 minutes and eliminated configuration drift.