Clicking through a cloud console to create servers works once — but it’s slow, error-prone, and impossible to reproduce. Terraform lets you describe your infrastructure in code, so you can create, change, and destroy it reliably and repeatably. This is Infrastructure as Code (IaC).

🎯 Learning Objectives

By the end of this lesson you will:

• Understand what Infrastructure as Code means
• Know what Terraform is and how it works
• Understand providers, resources, and the core workflow
• Recognise why declarative infrastructure matters

What is Infrastructure as Code?

Instead of manually provisioning servers, networks, and databases through a web console, you write code that describes what you want. That code is:

• Version-controlled — every change is tracked in Git.
• Reviewable — infrastructure changes go through pull requests.
• Repeatable — spin up an identical environment any time.
• Documented — the code is the documentation.

What Makes Terraform Special

Terraform is cloud-agnostic and declarative:

• Cloud-agnostic — the same tool manages AWS, Azure, GCP, Kubernetes, and hundreds of other platforms through providers.
• Declarative — you describe the desired end state, and Terraform figures out the steps to get there (create, update, or delete resources as needed).

You write:  "I want 3 servers and a load balancer"
Terraform:  compares desired vs actual → makes the minimal changes

The Building Blocks

A tiny example that creates an AWS S3 bucket:

terraform {
required_providers {
  aws = { source = "hashicorp/aws" }
}
}

provider "aws" {
region = "us-east-1"
}

resource "aws_s3_bucket" "data" {
bucket = "my-devops-course-bucket"
}

The language is HCL (HashiCorp Configuration Language) — readable and purpose-built for infrastructure.

The Core Workflow

Three commands do almost everything:

terraform init      # download providers, set up the working dir
terraform plan      # preview what will change
terraform apply     # make it real
terraform destroy   # tear it all down

Terraform will perform the following actions:

# aws_s3_bucket.data will be created
+ resource "aws_s3_bucket" "data" {
    + bucket = "my-devops-course-bucket"
    + id     = (known after apply)
  }

Plan: 1 to add, 0 to change, 0 to destroy.

plan shows you exactly what will happen before anything changes — no surprises.

🧪 Hands-on Lab

resource "local_file" "hello" {
filename = "hello.txt"
content  = "Infrastructure as Code!"
}

Terraform has been successfully initialized!
local_file.hello: Creating...
local_file.hello: Creation complete after 0s
Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
Infrastructure as Code!

🧠 Knowledge Check

💼 Interview Preparation

Summary

You now understand Infrastructure as Code, what Terraform is, its building blocks (providers, resources, state, plan), and the init → plan → apply workflow. Next, you’ll write real configuration with variables and outputs.