Infrastructure as Code Skill (Terraform)

Metadata (Tier 1)

Keywords: terraform, iac, infrastructure as code, module, state, tfvars

File Patterns: *.tf, *.tfvars, terraform.tfstate

Modes: gcp_dev, deployment

Instructions (Tier 2)

Remote State (MANDATORY)

hcl

terraform {
  backend "gcs" {
    bucket = "my-tf-state"
    prefix = "terraform/prod"
  }

  required_version = ">= 1.5.0"

  required_providers {
    google = {
      source  = "hashicorp/google"
      version = "~> 5.0"
    }
  }
}

Modular Structure

code

terraform/
├── environments/
│   ├── dev/
│   ├── staging/
│   └── prod/
└── modules/
    ├── cloud-run/
    ├── vpc/
    └── iam/

Variable Management

hcl

# variables.tf
variable "project_id" {
  type = string
}

# terraform.tfvars
project_id = "my-project"

# Use in resources
resource "google_cloud_run_service" "app" {
  project = var.project_id
}

Lifecycle Management

hcl

resource "google_cloud_run_service" "prod" {
  # ...

  lifecycle {
    prevent_destroy = true  # Protect production resources
    create_before_destroy = true  # Zero-downtime updates
  }
}

Module Pattern

hcl

module "api_service" {
  source = "../../modules/cloud-run"

  service_name = "api"
  image        = var.image_url
  min_instances = 2
  max_instances = 50
}

output "service_url" {
  value = module.api_service.url
}

Best Practices

✅ Remote state with GCS backend + locking ✅ Modular design with reusable components ✅ No hardcoded values (use variables) ✅ Version pinning for providers ✅ Lifecycle blocks for critical resources ✅ Separate environments (dev/staging/prod) ✅ Variable validation where appropriate

Workflow

bash

terraform init       # Initialize
terraform fmt        # Format code
terraform validate   # Syntax check
terraform plan       # Preview changes
terraform apply      # Apply changes

Anti-Patterns

❌ Local state in team projects ❌ Monolithic main.tf files ❌ Hardcoded credentials or secrets ❌ Using :latest for images ❌ No lifecycle blocks on production resources ❌ Mixing environments in same state