Terraform Best Practices for Production Infrastructure

Introduction

After years of managing infrastructure with Terraform across dozens of projects, these are the patterns that have consistently proven their value.

Project Structure

A well-organized Terraform project scales much better:

infrastructure/
├── modules/
│   ├── networking/
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── outputs.tf
│   ├── compute/
│   └── database/
├── environments/
│   ├── dev/
│   │   ├── main.tf
│   │   ├── terraform.tfvars
│   │   └── backend.tf
│   ├── staging/
│   └── production/
└── shared/
    └── state-backend/

Remote State Management

Always use remote state with locking:

terraform {
  backend "s3" {
    bucket         = "my-terraform-state"
    key            = "production/terraform.tfstate"
    region         = "ap-southeast-1"
    dynamodb_table = "terraform-locks"
    encrypt        = true
  }
}

State Locking

State locking prevents concurrent modifications:

# If you need to force-unlock (use with caution)
terraform force-unlock LOCK_ID

Module Design

Keep Modules Focused

Each module should manage a single concern:

module "vpc" {
  source = "./modules/networking"
 
  cidr_block         = "10.0.0.0/16"
  availability_zones = ["ap-southeast-1a", "ap-southeast-1b"]
  environment        = var.environment
}
 
module "eks" {
  source = "./modules/compute"
 
  vpc_id     = module.vpc.vpc_id
  subnet_ids = module.vpc.private_subnet_ids
  cluster_version = "1.28"
}

Validation and Testing

Variable Validation

variable "environment" {
  type = string
  validation {
    condition     = contains(["dev", "staging", "production"], var.environment)
    error_message = "Environment must be dev, staging, or production."
  }
}

Plan Before Apply

# Always review the plan
terraform plan -out=tfplan
 
# Apply only the reviewed plan
terraform apply tfplan

Conclusion

Good Terraform practices compound over time. Invest in module design, state management, and validation early — your future self will thank you.