PROJECT : Module Reuse + Outputs Consumption

(IAM User module reused + output consumed)

This project answers:

• Root vs Child module
• Inputs & Outputs
• Module reuse
• How root consumes child output
• State behavior

---

1️⃣ Project Structure (CERTIFICATION STYLE)

project-1-iam-reuse/
├── main.tf
└── modules/
    └── iam-user/
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

---

2️⃣ Child Module — IAM User

modules/iam-user/variables.tf

variable "user_name" {
  type = string
}

modules/iam-user/main.tf

resource "aws_iam_user" "this" {
  name = var.user_name
}

modules/iam-user/outputs.tf

output "user_arn" {
  value = aws_iam_user.this.arn
}

---

3️⃣ Root Module — Reusing SAME Module Twice

main.tf

provider "aws" {
  region = "us-west-1"
}

module "dev_user" {
  source    = "./modules/iam-user"
  user_name = "dev-user"
}

module "prod_user" {
  source    = "./modules/iam-user"
  user_name = "prod-user"
}

output "dev_user_arn" {
  value = module.dev_user.user_arn
}

output "prod_user_arn" {
  value = module.prod_user.user_arn
}

---

4️⃣ Commands (EXAM EXPECTED)

terraform init
terraform plan
terraform apply

---

5️⃣ What This Project Demonstrates (EXAM MAPPING)

Exam Topic	Demonstrated
Root module	main.tf
Child module	modules/iam-user
Module reuse	Same module twice
Input variables	user_name
Outputs	user_arn
Output consumption	module.dev_user.user_arn
State behavior	Both users in same state

---

6️⃣ Answers to Exam Questions (FROM THIS PROJECT)

Q: Can same module be reused multiple times?
✔️ YES — demonstrated by dev_user and prod_user

Q: Where are module outputs stored?
✔️ Terraform state

Q: Does deleting root module delete child resources?
✔️ YES — all resources tracked in state

---

PROJECT 2 — Module + for_each + Environment Pattern

(S3 module used for dev/prod with for_each)

This project answers:

• Module + for_each
• Environment separation
• Count vs for_each
• Certification-favorite pattern

---

1️⃣ Project Structure

project-2-s3-env/
├── main.tf
└── modules/
    └── s3-bucket/
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

---

2️⃣ Child Module — S3 Bucket

modules/s3-bucket/variables.tf

variable "bucket_name" {
  type = string
}

modules/s3-bucket/main.tf

resource "aws_s3_bucket" "this" {
  bucket = var.bucket_name
}

modules/s3-bucket/outputs.tf

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

---

3️⃣ Root Module — for_each Over Environments

main.tf

provider "aws" {
  region = "us-west-1"
}

locals {
  environments = {
    dev  = "dev-app-bucket-aj"
    prod = "prod-app-bucket-aj"
  }
}

module "s3" {
  source = "./modules/s3-bucket"
  for_each = local.environments

  bucket_name = each.value
}

output "bucket_names" {
  value = {
    for env, mod in module.s3 :
    env => mod.bucket_name
  }
}

---

4️⃣ Commands

terraform init
terraform plan
terraform apply

---

5️⃣ What This Project Demonstrates (EXAM MAPPING)

Exam Topic	Demonstrated
Module + for_each	YES
Environment pattern	dev / prod
locals usage	YES
Output map	YES
Deterministic resource creation	YES

---

6️⃣ Answers to Exam Questions (FROM THIS PROJECT)

Q: When should for_each be used instead of count?
✔️ When using named keys (dev/prod)

Q: Can modules be used with for_each?
✔️ YES — fully supported

Q: What does module.s3["dev"] represent?
✔️ Dev environment module instance

---

FINAL CERTIFICATION SUMMARY (MEMORIZE THIS)

Terraform modules encapsulate reusable infrastructure logic.
Root modules compose child modules, pass inputs, and consume outputs.
Modules can be reused, versioned, and instantiated using count or for_each.
All module resources are tracked in a single Terraform state.