Terraform Modules in Azure: Step-by-Step Guide with Count, for_each & YAML Examples

 

Introduction

In modern cloud environments, writing reusable and scalable infrastructure is critical. Using Terraform with Microsoft Azure, you can achieve this efficiently through Terraform modules.

This blog provides:
✅ Simple module example
✅ count implementation
✅ for_each implementation
✅ YAML-based configuration
✅ Fully working step-by-step code

---

📦 Step 1: Simple Terraform Module (Basic Example)

📁 Folder Structure

project/
├── main.tf
├── provider.tf
└── modules/
    └── rg/
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

---

🔹 Module Code

modules/rg/main.tf

resource "azurerm_resource_group" "rg" {
  name     = var.rg_name
  location = var.rg_location
}

modules/rg/variables.tf

variable "rg_name" {
  type = string
}

variable "rg_location" {
  type = string
}

modules/rg/outputs.tf

output "rg_name" {
  value = azurerm_resource_group.rg.name
}

---

🔹 Root Module

provider.tf

provider "azurerm" {
  features {}
}

main.tf

module "rg" {
  source = "./modules/rg"

  rg_name     = "demo-rg"
  rg_location = "eastus"
}

---

▶️ Run

terraform init
terraform plan
terraform apply

---

🔁 Step 2: Using count in Module (Multiple Resources)

variable "rg_names" {
  default = ["rg-dev", "rg-test", "rg-prod"]
}

module "rg" {
  source = "./modules/rg"

  count       = length(var.rg_names)
  rg_name     = var.rg_names[count.index]
  rg_location = "eastus"
}

👉 Creates:

• rg-dev
• rg-test
• rg-prod

---

🔄 Step 3: Using for_each (Recommended)

variable "rgs" {
  default = {
    dev  = "rg-dev"
    test = "rg-test"
    prod = "rg-prod"
  }
}

module "rg" {
  source = "./modules/rg"

  for_each = var.rgs

  rg_name     = each.value
  rg_location = "eastus"
}

---

📤 Output

output "rg_names" {
  value = {
    for key, mod in module.rg :
    key => mod.rg_name
  }
}

---

🧾 Step 4: Using YAML Configuration (Advanced)

📁 config.yaml

resource_groups:
  dev: rg-dev
  test: rg-test
  prod: rg-prod

---

🔹 Terraform Code

locals {
  config = yamldecode(file("${path.module}/config.yaml"))
}

module "rg" {
  source = "./modules/rg"

  for_each = local.config.resource_groups

  rg_name     = each.value
  rg_location = "eastus"
}

---

🧠 Key Concepts

Feature	Use
Module	Reusable code
count	Simple iteration
for_each	Map-based iteration
YAML	External config

---

⚖️ Count vs for_each

Feature	count	for_each
Input	List	Map
Stability	❌ Index-based	✅ Key-based
Recommended	⚠️ Limited	✅ Yes

---

🎯 Best Practices

• Use modules for reusable design
• Prefer for_each over count
• Use YAML for external configuration
• Keep modules small and focused
• Avoid hardcoding values

---

🎓 Learn with Eduarn

At Eduarn, we provide hands-on training on:

• Terraform
• Microsoft Azure

✔ Real-time projects
✔ Corporate training
✔ Job-oriented learning

👉 Visit: https://eduarn.com

---

🚀 Conclusion

Terraform modules are essential for building scalable, reusable, and production-ready infrastructure.

By mastering:

• Basic modules
• count
• for_each
• YAML configs

👉 You become a real-world DevOps engineer

---

🔥 Hashtags

#Terraform #Azure #DevOps #InfrastructureAsCode #CloudAutomation #TerraformModules #EduArn

Terraform Modules Explained with Azure Example (Reusable Infrastructure Made Easy)

 

📘 What is a Terraform Module?

In Terraform, a module is a container for multiple resources that are used together.

👉 Simple definition:
A module = reusable Terraform code block

• Root module → main configuration
• Child module → reusable components

---

🎯 Why Use Modules?

• Reusability (write once, use many times)
• Standardization across environments
• Cleaner and organized code
• Easy scaling for large infrastructure

---

☁️ Azure Use Case

Using AzureRM Provider, you can create reusable modules for:

• Resource Groups
• Virtual Networks
• Storage Accounts
• AKS Clusters

---

📁 Project Structure

/home/user/tfmodule
│
├── provider.tf
├── m_imp_rg.tf
└── modules/
    └── rg/
        ├── rg.tf
        ├── variable.tf
        └── output.tf

---

⚙️ Module Code (Resource Group)

📌 modules/rg/rg.tf

resource "azurerm_resource_group" "rg" {
  name     = var.rg_name
  location = var.rg_location

  tags = {
    environment = "Dev"
  }
}

---

📌 modules/rg/variable.tf

variable "rg_name" {
  default = "demo_rg"
}

variable "rg_location" {
  default = "eastus"
}

---

📌 modules/rg/output.tf

output "rg_output" {
  value = azurerm_resource_group.rg
}

👉 This output exposes the resource group details to the root module.

---

🧩 Root Module Usage

📌 provider.tf

provider "azurerm" {
  features {}
}

---

📌 m_imp_rg.tf

module "prj_001_rg" {
  source      = "./modules/rg"
  rg_name     = "mydemorg"
  rg_location = "eastus"
}

module "prj_002_rg" {
  source      = "./modules/rg"
  rg_name     = "mydemorg2"
  rg_location = "eastus"
}

👉 Same module reused twice → creates two resource groups

---

📤 Access Module Output

output "myoutput" {
  value = module.prj_001_rg.rg_output
}

👉 Syntax:

module.<module_name>.<output_name>

---

🔎 What Happens Here?

• Module rg is defined once
• Called multiple times with different inputs
• Each call creates a separate Azure Resource Group
• Outputs allow sharing values

---

💡 Real-World Benefits

• Create 10+ resource groups using one module
• Maintain consistency across environments
• Reduce duplication and errors
• Faster deployments

---

🧠 Best Practices

• Keep modules small and focused
• Use variables for flexibility
• Expose only required outputs
• Follow naming conventions
• Store modules in version-controlled repos

---

🎓 Learn with EduArn

At Eduarn, we teach real-world DevOps using:

• Terraform
• Azure cloud projects
• Hands-on labs and corporate scenarios

✔ Retail training (individual learners)
✔ Corporate training (team upskilling)

---

🚀 Final Thoughts

Terraform modules are the foundation of scalable infrastructure design.

If you're not using modules yet, you're:
❌ Writing duplicate code
❌ Increasing risk
❌ Slowing down deployments

👉 Start modularizing today and build like a pro DevOps engineer.

---

#Terraform #Azure #DevOps #InfrastructureAsCode #TerraformModules #CloudComputing #EduArn

 

 Copy Pest code:

#!/bin/bash

# Create directory structure
mkdir -p tfmodule/modules/rg
cd tfmodule || exit

# Create provider.tf
cat <<EOF > provider.tf
provider "azurerm" {
  features {}
}
EOF

# Create main module usage file
cat <<EOF > m_imp_rg.tf
module "prj_001_rg" {
  source      = "./modules/rg"
  rg_name     = "mydemorg"
  rg_location = "eastus"
}

module "prj_002_rg" {
  source      = "./modules/rg"
  rg_name     = "mydemorg2"
  rg_location = "eastus"
}

output "myoutput" {
  value = module.prj_001_rg.rg_output
}
EOF

# Create module: rg.tf
cat <<EOF > modules/rg/rg.tf
resource "azurerm_resource_group" "rg" {
  name     = var.rg_name
  location = var.rg_location

  tags = {
    environment = "Dev"
  }
}
EOF

# Create module: variable.tf
cat <<EOF > modules/rg/variable.tf
variable "rg_name" {
  default = "demo_rg"
}

variable "rg_location" {
  default = "eastus"
}
EOF

# Create module: output.tf
cat <<EOF > modules/rg/output.tf
output "rg_output" {
  value = azurerm_resource_group.rg
}
EOF

echo "✅ Terraform module structure created successfully!"
echo "👉 Next steps:"
echo "1. terraform init"
echo "2. terraform plan"
echo "3. terraform apply"