Modules: Reusable Infrastructure

infrastructure/
├── main.tf
├── variables.tf
├── outputs.tf
└── modules/
    └── web-server/
        ├── main.tf       ← module resources
        ├── variables.tf  ← module inputs
        └── outputs.tf    ← module outputs

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

variable "name" {
  type = string
}

variable "subnet_id" {
  type = string
}

variable "security_group_ids" {
  type = list(string)
}

module "web" {
  source = "./modules/web-server"

  name               = "production-web"
  instance_type      = "t3.small"
  subnet_id          = aws_subnet.public.id
  security_group_ids = [aws_security_group.web.id]
}

# Public registry modules
module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.1.0"

  name = "my-vpc"
  cidr = "10.0.0.0/16"
  azs  = ["us-east-1a", "us-east-1b"]
}