infrastructure-as-code

Infrastructure as Code (IaC)

Automate infrastructure provisioning and management using declarative configuration with Terraform, enabling version-controlled, repeatable, and scalable infrastructure deployment.

Level 1: Quick Reference

Core Workflow

# Initialize Terraform
terraform init

# Preview changes
terraform plan -out=tfplan

# Apply changes
terraform apply tfplan

# Destroy infrastructure
terraform destroy

# Validate configuration
terraform validate

# Format code
terraform fmt -recursive

Essential Patterns

Basic Resource:

resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = var.instance_type

  tags = {
    Name        = "${var.environment}-web"
    Environment = var.environment
  }
}

Module Usage:

module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "~> 5.0"

  name = "${var.environment}-vpc"
  cidr = var.vpc_cidr

  azs             = var.availability_zones
  private_subnets = var.private_subnet_cidrs
  public_subnets  = var.public_subnet_cidrs

  enable_nat_gateway = true
  enable_vpn_gateway = false
}

Remote State:

terraform {
  backend "s3" {
    bucket         = "terraform-state-prod"
    key            = "networking/vpc/terraform.tfstate"
    region         = "us-east-1"
    encrypt        = true
    dynamodb_table = "terraform-locks"
  }
}

Critical Checklist

• Pin provider versions (version = "~> 5.0")
• Enable remote state with locking
• Use workspaces for environments
• Implement .gitignore for secrets
• Run terraform validate before commit
• Review plan output before apply
• Tag all resources consistently
• Use variables for all environment-specific values
• Document module inputs/outputs
• Enable state encryption

Common Commands

# Workspace management
terraform workspace new dev
terraform workspace select prod
terraform workspace list

# State management
terraform state list
terraform state show aws_instance.web
terraform state mv aws_instance.old aws_instance.new
terraform state rm aws_instance.deprecated

# Import existing resources
terraform import aws_instance.web i-1234567890abcdef0

# Output values
terraform output
terraform output -json vpc_id