The Complete Guide to Terraform¶

Infrastructure as Code with Terraform. Declarative, reproducible, version-controlled.

What is Terraform¶

A declarative tool for managing infrastructure. You write what you want, Terraform creates it.

Basic Workflow¶

terraform init # downloads providers terraform plan # shows what will change terraform apply # applies changes terraform destroy # deletes everything

HCL Syntax¶

provider “aws” { region = “eu-west-1” }

resource “aws_instance” “web” { ami = “ami-12345” instance_type = “t3.micro” tags = { Name = “web-server” } }

State¶

Terraform stores infrastructure state. In a team, use remote state (S3 + DynamoDB lock).

terraform { backend “s3” { bucket = “tf-state” key = “prod/terraform.tfstate” region = “eu-west-1” } }

Variables¶

variable “instance_type” { default = “t3.micro” type = string } variable “tags” { type = map(string) }

Modules¶

module “vpc” { source = “./modules/vpc” cidr = “10.0.0.0/16” }

Best Practices¶

• Remote state with locking
• Small, focused modules
• terraform plan in CI/CD
• Immutable infrastructure
• Tagging convention

Tip¶

Never change infrastructure manually. Everything through Terraform. Drift = problems.