terraform

Terraform Infrastructure as Code Skill

Step 1: Project Structure

infra/
├── main.tf              # Main resource definitions
├── variables.tf         # Input variable declarations
├── outputs.tf           # Output values
├── versions.tf          # Required providers and Terraform version
├── locals.tf            # Local values (computed names, tags)
├── backend.tf           # Remote state configuration
├── terraform.tfvars     # Variable values (gitignored for secrets)
├── terraform.tfvars.example  # Template for required vars
└── modules/
    ├── networking/
    │   ├── main.tf
    │   ├── variables.tf
    │   └── outputs.tf
    └── compute/
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

Step 2: Provider and Version Pinning

# versions.tf
terraform {
  required_version = ">= 1.7.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
    cloudflare = {
      source  = "cloudflare/cloudflare"
      version = "~> 4.0"
    }
  }
}

provider "aws" {
  region = var.aws_region

  default_tags {
    tags = local.common_tags
  }
}

Step 3: Variables and Locals

# variables.tf
variable "environment" {
  description = "Deployment environment (dev, staging, prod)"
  type        = string

  validation {
    condition     = contains(["dev", "staging", "prod"], var.environment)
    error_message = "environment must be dev, staging, or prod"
  }
}

variable "app_name" {
  description = "Application name used in resource naming"
  type        = string
}

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

variable "database_password" {
  description = "Database master password"
  type        = string
  sensitive   = true  # never shown in plan/apply output
}

# locals.tf
locals {
  name_prefix  = "${var.app_name}-${var.environment}"
  is_prod      = var.environment == "prod"

  common_tags = {
    App         = var.app_name
    Environment = var.environment
    ManagedBy   = "Terraform"
  }
}