04-Modules-and-Dependency-Management

Modules and Dependency Management

What you'll learn

• Break infrastructure into reusable modules with clear interfaces.
• Pass variables between root modules and child modules.
• Manage module versioning and the module registry workflow.
• Use depends_on, for_each, and data sources to handle relationships.

Topics

• Modules and Backends

Cheat sheet

• Call a module:

  module "network" {
    source = "./modules/network"
    cidr_block = "10.0.0.0/16"
  }

• Pin module versions: version = "~> 2.0"
• Explicit dependency: depends_on = [module.network]

Official documentation

• Module Overview
• Module Registry
• Module Best Practices

Hands-on task

Create a simple module structure:

mkdir -p modules/random_pet
cat <<'HCL' > modules/random_pet/main.tf
resource "random_pet" "this" {
  prefix = var.prefix
}

output "name" {
  value = random_pet.this.id
}
HCL
cat <<'HCL' > modules/random_pet/variables.tf
variable "prefix" {
  type = string
}
HCL

Then consume it in main.tf and run terraform init && terraform apply to observe the generated pet name.