Terraform Infrastructure as Code: AWS, Azure and Hetzner Examples

Terraform lets you define your cloud infrastructure (servers, networks, databases, DNS, firewalls) as code, with versioning, review and reproducibility. Clicking through a cloud console in production often ends in mistakes; with Terraform you can recreate the same cluster in ten different regions in seconds.

Basic Structure

# main.tf
terraform {
  required_version = ">= 1.6"
  required_providers {
    hcloud = {
      source  = "hetznercloud/hcloud"
      version = "~> 1.45"
    }
  }
  backend "s3" {
    bucket = "my-tf-state"
    key    = "prod/terraform.tfstate"
    region = "eu-central-1"
  }
}

provider "hcloud" {
  token = var.hcloud_token
}

Essential Commands

terraform init       # download providers, set up backend
terraform fmt -recursive
terraform validate
terraform plan       # WHAT will change? — read this before applying
terraform apply      # apply (re-shows plan, asks for confirmation)
terraform destroy    # delete everything (be careful!)

terraform state list
terraform state show hcloud_server.web
terraform output

Variables

# variables.tf
variable "hcloud_token" {
  type      = string
  sensitive = true
}

variable "server_count" {
  type    = number
  default = 2
  validation {
    condition     = var.server_count > 0 && var.server_count <= 10
    error_message = "Must be between 1 and 10."
  }
}

variable "region" {
  type    = string
  default = "nbg1"
}

# terraform.tfvars
hcloud_token = "your-token"
server_count = 3

Hetzner Example: Web + DB

resource "hcloud_ssh_key" "admin" {
  name       = "admin"
  public_key = file("~/.ssh/id_ed25519.pub")
}

resource "hcloud_network" "internal" {
  name     = "internal"
  ip_range = "10.0.0.0/16"
}

resource "hcloud_network_subnet" "main" {
  network_id   = hcloud_network.internal.id
  type         = "cloud"
  network_zone = "eu-central"
  ip_range     = "10.0.1.0/24"
}

resource "hcloud_server" "web" {
  count       = var.server_count
  name        = "web-${count.index + 1}"
  image       = "ubuntu-24.04"
  server_type = "cx22"
  location    = var.region
  ssh_keys    = [hcloud_ssh_key.admin.id]

  network {
    network_id = hcloud_network.internal.id
    ip         = "10.0.1.${10 + count.index}"
  }

  user_data = file("cloud-init.yaml")
}

resource "hcloud_load_balancer" "web_lb" {
  name               = "web-lb"
  load_balancer_type = "lb11"
  location           = var.region
}

Modules

Factor repeated infrastructure into modules — write once, reuse across environments.

# modules/webapp/main.tf
variable "name" {}
variable "count" { default = 1 }

resource "hcloud_server" "this" {
  count       = var.count
  name        = "${var.name}-${count.index + 1}"
  image       = "ubuntu-24.04"
  server_type = "cx22"
}

output "ips" {
  value = hcloud_server.this[*].ipv4_address
}

# main.tf
module "frontend" {
  source = "./modules/webapp"
  name   = "frontend"
  count  = 3
}

module "backend" {
  source = "./modules/webapp"
  name   = "backend"
  count  = 2
}

State Management

Terraform stores the current state of your infrastructure in terraform.tfstate. On a team, remote state is mandatory — otherwise two concurrent applies will corrupt the state.

# S3 + DynamoDB lock
terraform {
  backend "s3" {
    bucket         = "my-tf-state"
    key            = "prod/terraform.tfstate"
    region         = "eu-central-1"
    dynamodb_table = "tf-state-locks"  # state lock
    encrypt        = true
  }
}

# Alternatives: Terraform Cloud (HashiCorp), GCS, Azure Blob

Workspaces

terraform workspace new staging
terraform workspace new production
terraform workspace select production
terraform workspace list

# Workspace-specific tfvars
terraform apply -var-file="prod.tfvars"

Drift Detection

# Did someone change infra manually?
terraform plan -detailed-exitcode
# exit 0: no changes
# exit 2: the plan includes changes
# Run this regularly in CI → alert

Importing Existing Resources

# Resource created by hand in the UI, bring it under Terraform:
terraform import hcloud_server.web 12345678

# Terraform 1.5+ — import blocks
import {
  to = hcloud_server.web
  id = "12345678"
}

Terraform + CI/CD

# .github/workflows/terraform.yml
name: Terraform
on:
  pull_request:
    paths: ['terraform/**']
jobs:
  plan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: hashicorp/setup-terraform@v3
      - run: terraform init
        working-directory: terraform
      - run: terraform fmt -check -recursive
      - run: terraform validate
      - run: terraform plan -out=plan.bin
        env:
          TF_VAR_hcloud_token: ${{ secrets.HCLOUD_TOKEN }}

Conclusion

Terraform is the written contract of modern cloud infrastructure. Infrastructure as code, PR review, versioning, reproducibility — all way beyond a single YAML file. It feels slow the first time; but cloning your infrastructure in five minutes on the second project becomes addictive.