Terraform Profile¶

Concept → Terraform Mapping¶

ABC Concept	Meaning	Terraform Mapping
ABC‑C0	Construct	Terraform module
ABC‑C1	Application Stack	Root Terraform module
ABC‑C2	Logical Unit	Child module representing a domain
ABC‑C3	Resource Group	Submodule representing a cohesive resource cluster
ABC‑C4	Input Contract	variables.tf in a module
ABC‑C5	Output Contract	outputs.tf in a module
ABC‑C6	Instantiation Interface	`module "" { ... }` block
ABC‑C7	Capturing Down	Passing variables from parent to child module
ABC‑C8	Bubbling Up	Exposing outputs from child modules to parent

Proile Rules¶

Terraform profile rules follow the canonical identifier format:

ABC-PROFILE-TF-R#

These rules are profile‑specific, not core ABC rules.

ABC-PROFILE-TF-R1 (SHOULD)¶

Each ABC construct SHOULD be implemented as a Terraform module.

ABC-PROFILE-TF-R2 (SHOULD)¶

The directory structure SHOULD reflect the ABC hierarchy:

root/
  main.tf
  data/
    main.tf
    storage/
      main.tf
    database/
      main.tf
  logic/
    main.tf
  presentation/
    main.tf

ABC-PROFILE-TF-R3 (SHOULD)¶

Each module SHOULD contain:

main.tf
variables.tf (InputContract)
outputs.tf (OutputContract)

ABC-PROFILE-TF-R4 (MUST)¶

Module inputs MUST be declared exclusively in variables.tf.

ABC-PROFILE-TF-R5 (MUST)¶

Module outputs MUST be declared exclusively in outputs.tf.

ABC-PROFILE-TF-R6 (MUST)¶

Modules MUST NOT reference parent or sibling modules directly; all data MUST flow through variables and outputs.

(This enforces ABC‑R22, ABC‑R40, ABC‑R42.)

ABC-PROFILE-TF-R7 (MUST)¶

Modules MUST be instantiated using a module “<name>” { … } block with explicit variable assignments.

ABC-PROFILE-TF-R8 (MUST)¶

Modules MUST NOT read Terraform state from other modules except via outputs.

ABC-PROFILE-TF-R9 (MUST)¶

Capturing Down MUST be implemented by passing parent variables or outputs into child module inputs.

ABC-PROFILE-TF-R10 (MUST)¶

Bubbling Up MUST be implemented by exposing child module outputs and re‑exposing them in the parent module if needed.

ABC-PROFILE-TF-R11 (MUST)¶

Resource definitions MUST reside only in Resource Group modules (ABC‑C3).

ABC-PROFILE-TF-R12 (MUST)¶

Logical Units MUST NOT contain Terraform resources directly.

ABC-PROFILE-TF-R13 (SHOULD)¶

Logical Units SHOULD only orchestrate child modules and expose aggregated outputs.

Canonical Example¶

A minimal 3‑tier ABC architecture in Terraform.

Application Stack¶

main.tf¶

module "data" {
  source = "./data"
  environment = var.environment
  region      = var.region
}

module "logic" {
  source = "./logic"
  environment      = var.environment
  region           = var.region
  database_endpoint = module.data.database_endpoint
}

module "presentation" {
  source = "./presentation"
  environment           = var.environment
  region                = var.region
  frontend_assets_bucket = module.data.storage_bucket_name
  api_endpoint           = module.logic.api_endpoint
}

output "frontend_url" {
  value = module.presentation.frontend_url
}

output "api_endpoint" {
  value = module.logic.api_endpoint
}

variables.tf¶

variable "environment" { type = string }
variable "region"      { type = string }

Data Logical Unit¶

data/main.tf¶

module "storage" {
  source = "./storage"
  environment  = var.environment
  region       = var.region
  storage_class = var.storage_class
}

module "database" {
  source = "./database"
  environment      = var.environment
  db_engine        = var.db_engine
  db_instance_size = var.db_instance_size
}

output "storage_bucket_name" {
  value = module.storage.bucket_name
}

output "database_endpoint" {
  value = module.database.endpoint
}

data/variables.tf¶

variable "environment"   { type = string }
variable "region"        { type = string }
variable "storage_class" { type = string }
variable "db_engine"     { type = string }
variable "db_instance_size" { type = string }

Storage Resource Group¶

data/storage/main.tf¶

resource "aws_s3_bucket" "bucket" {
  bucket = "${var.environment}-storage"
}

data/storage/variables.tf¶

variable "environment"   { type = string }
variable "region"        { type = string }
variable "storage_class" { type = string }

data/storage/outputs.tf¶

output "bucket_name" {
  value = aws_s3_bucket.bucket.bucket
}