🗂 Project Structure

The Terraform project consists of the following files:

azure-linuxvm-nsg-nginx-demo/
├── main.tf # Main infrastructure definitions
├── variables.tf # Input variable declarations
├── terraform.tfvars # Variable values (location, credentials, etc.)
├── outputs.tf # Outputs like public IP
├── startup-script.sh # Bash script to install and enable nginx

Each file serves a specific purpose to keep the project modular, secure, and easy to manage.

🔧 Terraform Configuration Breakdown

This section explains each component used in the deployment.

1. Resource Group

resource "azurerm_resource_group" "rg" {
  name     = var.resource_group_name
  location = var.location
}
💡 Creates a container to hold all related Azure resources.

2. Virtual Network and Subnet

resource "azurerm_virtual_network" "vnet" {
  name                = "vnet-demo"
  address_space       = ["10.0.0.0/16"]
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
}

resource "azurerm_subnet" "subnet" {
  name                 = "subnet-demo"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.vnet.name
  address_prefixes     = ["10.0.1.0/24"]
}
💡 Defines the internal network where the VM will reside.

3. Public IP Address

resource "azurerm_public_ip" "public_ip" {
  name                = "public-ip-demo"
  location            = var.location
  resource_group_name = var.resource_group_name
  allocation_method   = "Dynamic"
}
💡 Allows the VM to be accessible from the internet.

4. Network Security Group (NSG)
resource "azurerm_network_security_group" "nsg" {
  name                = "nsg-demo"
  location            = var.location
  resource_group_name = var.resource_group_name

  security_rule {
    name                       = "SSH"
    priority                   = 1001
    direction                  = "Inbound"
    access                     = "Allow"
    protocol                   = "Tcp"
    source_port_range          = "*"
    destination_port_range     = "22"
    source_address_prefix      = "*"
    destination_address_prefix = "*"
  }

  security_rule {
    name                       = "HTTP"
    priority                   = 1002
    direction                  = "Inbound"
    access                     = "Allow"
    protocol                   = "Tcp"
    source_port_range          = "*"
    destination_port_range     = "80"
    source_address_prefix      = "*"
    destination_address_prefix = "*"
  }
}
💡 Allows traffic to ports 22 (SSH) and 80 (HTTP) from any IP.

5. Network Interface + NSG Binding
resource "azurerm_network_interface" "nic" {
  name                = "nic-demo"
  location            = var.location
  resource_group_name = var.resource_group_name

  ip_configuration {
    name                          = "ipconfig"
    subnet_id                     = azurerm_subnet.subnet.id
    private_ip_address_allocation = "Dynamic"
    public_ip_address_id          = azurerm_public_ip.public_ip.id
  }

  network_security_group_id = azurerm_network_security_group.nsg.id
}
💡 Binds the NIC to the subnet and NSG. Associates a public IP.

---

### 6. Startup Script: `startup-script.sh`

bash

!/bin/bash

sudo apt-get update
sudo apt-get install -y nginx
sudo systemctl start nginx
sudo systemctl enable nginx

💡 This script installs and starts nginx automatically when the VM is created.

1. Linux Virtual Machine resource "azurerm_linux_virtual_machine" "vm" { name = var.vm_name location = var.location resource_group_name = var.resource_group_name network_interface_ids = [azurerm_network_interface.nic.id] size = "Standard_B1s" admin_username = var.admin_username admin_password = var.admin_password disable_password_authentication = false

source_image_reference {
publisher = "Canonical"
offer = "UbuntuServer"
sku = "18.04-LTS"
version = "latest"
}

os_disk {
caching = "ReadWrite"
storage_account_type = "Standard_LRS"
name = "osdisk-demo"
}

computer_name = "demo-vm"
provision_vm_agent = true
custom_data = base64encode(file("startup-script.sh"))
}
💡 This creates a Linux VM and runs the startup script to configure the web server.

1. Outputs output "resource_group_name" { value = azurerm_resource_group.rg.name }

output "public_ip_address" {
value = azurerm_public_ip.public_ip.ip_address
}
💡 After deployment, these outputs help you identify the resource group and access the VM.

✅ Conclusion

With just a few Terraform files, we successfully deployed:

• A secure Linux Virtual Machine on Azure
• A fully working nginx web server
• Automated provisioning via a startup script
• Public access through a dynamically assigned IP address

This approach demonstrates the power of Infrastructure as Code (IaC) and how easily repeatable environments can be created using Terraform.

📦 GitHub Repository

You can find the full source code for this project here:

👉 https://github.com/Smallsun2025/azure-linuxvm-nsg-nginx-demo

⭐️ Feel free to star, fork, or leave feedback!

🧠 Coming Next

In future posts, I’ll walk through:

• Creating Azure VM images with Packer + Terraform
• Setting up 3-tier architecture with Load Balancer
• Using Terraform Cloud for remote state & collaboration

Follow for more Azure automation tips!