What Is Infrastructure as Code (IaC)?

Infrastructure as Code (IaC) is the approach of defining and managing your infrastructure (servers, networks, databases) with version-controlled code files instead of clicking around a cloud console. Whatever the code says, the infrastructure is.

The problem with manual setup

• Not reproducible: you can't rebuild the same environment identically twice
• Undocumented: no record of who changed what and why
• Error-prone: manual clicking = human error
• Doesn't scale: managing 50 servers by hand is impossible

What IaC solves

Because your infrastructure is now code: it's versioned in Git (who changed what, when), goes through code review, can be rebuilt from scratch with one command, and keeps dev/test/prod identical.

First step with Terraform

Terraform is the most common IaC tool and works with many providers (AWS, GCP, Azure...). You write the desired state declaratively; Terraform computes the diff against reality and applies it:

resource "aws_s3_bucket" "data" {
  bucket = "cloudpuz-example-bucket"
}

# terraform init  → initialize
# terraform plan  → see what will happen
# terraform apply → apply

Case: adopt a hand-created resource into IaC

In real life most teams inherit hand-built infrastructure and bring it under IaC later. Let's put an S3 bucket created via the console under Terraform management — without deleting and recreating it.

1. 1Declare the resource in code (don't apply yet)
2. 2Bind the existing resource to state with terraform import
3. 3terraform plan → align code to reality until you see 'No changes'
4. 4Now it's IaC-managed: changes go through code review + plan

$ terraform import aws_s3_bucket.data cloudpuz-existing-bucket
Import successful!
$ terraform plan
  ~ aws_s3_bucket.data  tags: {} -> {Env="prod"}   # code and reality differ
# Align code to reality (add the tags), then:
$ terraform plan
No changes. Your infrastructure matches the configuration.   # ✓ now IaC-managed

IaC is central to modern DevOps. To practice Terraform state, modules, and real providers, check out Cloudpuz's Terraform labs.