Terraform Fundamentals: Infrastructure as Code

What is Terraform?

Terraform is an open-source Infrastructure as Code (IaC) tool by HashiCorp. It lets you define cloud and on-prem resources in human-readable configuration files that you can version, reuse, and share.

Core Concepts

Providers

Providers are plugins that let Terraform interact with cloud platforms and services. AWS, Azure, GCP, and hundreds of others are supported.

provider "aws" {
  region = "ap-south-1"
}

Resources

Resources are the most important element in Terraform. Each resource block describes one or more infrastructure objects.

resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"

  tags = {
    Name        = "web-server"
    Environment = "production"
  }
}

Variables

Variables make your configurations flexible and reusable.

variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

The Terraform Workflow

1. terraform init — Initialize the working directory
2. terraform plan — Preview changes before applying
3. terraform apply — Apply the planned changes
4. terraform destroy — Tear down all managed resources

State Management

Terraform maintains a state file that maps real-world resources to your configuration. For team collaboration, store state remotely:

terraform {
  backend "s3" {
    bucket = "my-terraform-state"
    key    = "prod/terraform.tfstate"
    region = "ap-south-1"
  }
}

Conclusion

Terraform transforms infrastructure management from manual, error-prone processes into reproducible, version-controlled code. Start small, build modules, and gradually adopt it across your entire infrastructure.