Introduction to Terraform

What is Terraform?

Terraform is an open-source Infrastructure as Code tool by HashiCorp. You describe infrastructure in HCL (HashiCorp Configuration Language), and Terraform creates, updates, or destroys cloud resources to match.

Use it to:

• Create infrastructure
• Modify infrastructure
• Delete infrastructure

All from code.

Why Terraform?

• Multi-cloud — AWS, Azure, GCP, and hundreds of providers
• Open source — large community and provider ecosystem
• Declarative — describe desired state, not step-by-step scripts
• State management — tracks what already exists
• Reusable modules — package and share common patterns
• Version control friendly — .tf files live in Git

Terraform vs CloudFormation

Terraform Architecture

.tf configuration files
        ↓
   Terraform Core
   (plan + apply)
        ↓
     Providers
   (aws, azurerm, …)
        ↓
    Cloud APIs
        ↓
     Resources
   (EC2, S3, VPC, …)

Components

Terraform configuration — .tf files that declare providers and resources.

Terraform Core — reads config and state, builds an execution plan, and applies changes.

Provider — plugin that knows how to talk to a specific platform (for example hashicorp/aws).

Cloud APIs — the real create/update/delete calls made on your behalf.

Resources — the individual objects you manage (aws_instance, aws_s3_bucket, …).

Terraform Workflow

Write .tf code
        ↓
terraform init
        ↓
terraform plan
        ↓
terraform apply
        ↓
Infrastructure created

Important commands

terraform init      # download providers, prepare the working directory
terraform plan      # preview what will change
terraform apply     # create / update infrastructure
terraform destroy   # tear everything down
terraform validate  # check syntax and basic configuration
terraform version   # show installed version