# Exercise: Refactoring Configurations into Reusable Modules

# Objective

Participants will refactor their existing configurations (such as the one for provisioning a web server) into reusable modules. This exercise will help participants organize and parameterize their Terraform code, making it easier to reuse across different projects and environments.

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# Steps

# Step 1: Create a New Directory for the Module

1. Create a Module Directory:

   • Open your terminal and navigate to the project directory.
   • Create a new directory named modules/webserver to hold the reusable web server module:

     mkdir -p modules/webserver

2. Verify Directory Structure:

   • Your project directory should now contain the following structure:

     .
     ├── main.tf
     └── modules
         └── webserver

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# Step 2: Move the Existing Web Server Configuration into the Module

1. Open Your Web Server Configuration:

   • Locate your existing web server configuration (typically defined in main.tf).

2. Move the Web Server Configuration to the Module Directory:

   • Move the resource blocks that define the web server (e.g., Virtual Machine, Network Interface, Public IP) from main.tf to a new file named main.tf inside modules/webserver.

3. Example main.tf for the Module:

   • In modules/webserver/main.tf, the configuration might look like this:

     resource "azurerm_network_interface" "example" {
       name                = "example-nic"
       location            = var.location
       resource_group_name = var.resource_group_name
       ip_configuration {
         name                          = "internal"
         subnet_id                     = azurerm_subnet.example.id
         private_ip_address_allocation = "Dynamic"
       }
     }
     
     resource "azurerm_virtual_machine" "example" {
       name                  = "example-vm"
       location              = var.location
       resource_group_name   = var.resource_group_name
       network_interface_ids = [azurerm_network_interface.example.id]
       vm_size               = "Standard_DS1_v2"
     
       storage_image_reference {
         publisher = "Canonical"
         offer     = "UbuntuServer"
         sku       = "18.04-LTS"
         version   = "latest"
       }
     
       os_profile {
         computer_name  = "examplevm"
         admin_username = "adminuser"
         admin_password = "P@ssw0rd123!"
       }
     
       os_profile_linux_config {
         disable_password_authentication = false
       }
     }

4. Save the Module Configuration.

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# Step 3: Define Input Variables in variables.tf for the Module

1. Create a variables.tf File in the Module Directory:

   • In modules/webserver, create a new file named variables.tf.

2. Define Variables for Resource Group Name and Location:

   • Add variables to parameterize the Resource Group name and location:

     variable "resource_group_name" {
       description = "The name of the resource group"
       type        = string
     }
     
     variable "location" {
       description = "The location for the web server resources"
       type        = string
     }

3. Save the variables.tf File.

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# Step 4: Create outputs.tf to Capture and Return Useful Information

1. Create an outputs.tf File in the Module Directory:

   • In modules/webserver, create a new file named outputs.tf.

2. Define Outputs for Useful Information:

   • Capture information such as the public IP address of the Virtual Machine:

     output "vm_id" {
       description = "The ID of the virtual machine"
       value       = azurerm_virtual_machine.example.id
     }
     
     output "public_ip_address" {
       description = "The public IP address of the virtual machine"
       value       = azurerm_network_interface.example.ip_configuration[0].private_ip_address
     }

3. Save the outputs.tf File.

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# Step 5: Call the Module in the Root Configuration (main.tf)

1. Open the Root main.tf File:

   • Open the main.tf file in the root directory of your project.

2. Add a Module Block to Call the webserver Module:

   • Call the webserver module by specifying its source directory and passing in the necessary variables:

     module "webserver" {
       source              = "./modules/webserver"
       resource_group_name = "myResourceGroup"
       location            = "East US"
     }

3. Save the main.tf File.

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# Step 6: Run Terraform Commands to Test the Module

1. Initialize the Project:

   • In the terminal, run terraform init to ensure that all module dependencies are loaded and the project is ready:

     terraform init

2. Run terraform plan to Preview the Changes:

   • Run terraform plan to review the resources that will be created by the webserver module:

     terraform plan

   • Ensure that the output includes the expected resources, such as the Virtual Machine and Network Interface.

3. Run terraform apply to Deploy the Module:

   • Apply the configuration to create the web server resources using the module:

     terraform apply

   • Type yes when prompted to confirm the apply operation.

4. Review the Output Values:

   • After the apply completes, observe the output values defined in outputs.tf, such as the VM ID and public IP address.

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# Verification

• Confirm Resource Creation in Azure:

  • Log in to the Azure Portal and check the Resource Group specified in the module call.
  • Verify that the web server resources (e.g., Virtual Machine, Network Interface) have been created with the correct settings.

• Check Output Values:

  • Ensure that the output values displayed in the terminal match the expected details for the VM and network configurations.

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