Infrastructure as Code with Terraform Basics

What is Terraform?

Terraform by HashiCorp lets you define infrastructure in code files. Instead of clicking through web dashboards, you write declarative configuration that can be version-controlled, reviewed, and reproduced.

Installation

wget https://releases.hashicorp.com/terraform/1.7.0/terraform_1.7.0_linux_amd64.zip
unzip terraform_*.zip
sudo mv terraform /usr/local/bin/
terraform version

Basic Structure

A Terraform project typically has these files:

• main.tf — resource definitions
• variables.tf — input variables
• outputs.tf — output values
• terraform.tfvars — variable values (don't commit secrets)

Example Configuration

# main.tf
terraform {
  required_providers {
    local = {
      source = "hashicorp/local"
    }
  }
}

resource "local_file" "example" {
  content  = "Hello, Terraform!"
  filename = "${path.module}/hello.txt"
}

Workflow

# Initialize (download providers)
terraform init

# Preview changes
terraform plan

# Apply changes
terraform apply

# Destroy resources
terraform destroy

State Management

Terraform tracks resource state in terraform.tfstate. For team use, store state remotely:

• AWS S3 + DynamoDB for locking
• Terraform Cloud (free tier available)
• GitLab-managed state

Key Concepts

• Resources — infrastructure objects (servers, networks, DNS records)
• Providers — plugins for each cloud/service
• Modules — reusable groups of resources
• State — Terraform's record of what it manages