Quickstart: Use Terraform to create a virtual network

In this quickstart, you learn about a Terraform script that creates an Azure resource group and a virtual network with two subnets. The script generates the names of the resource group and the virtual network by using a random pet name with a prefix. The script also shows the names of the created resources in output.

The script uses the Azure Resource Manager (azurerm) provider to interact with Azure resources. It uses the Random (random) provider to generate random pet names for the resources.

The script creates the following resources:

• A resource group: A container that holds related resources for an Azure solution.

• A virtual network: A fundamental building block for your private network in Azure.

• Two subnets: Segments of a virtual network's IP address range where you can place groups of isolated resources.

Terraform enables the definition, preview, and deployment of cloud infrastructure. Using Terraform, you create configuration files using HCL syntax. The HCL syntax allows you to specify the cloud provider - such as Azure - and the elements that make up your cloud infrastructure. After you create your configuration files, you create an execution plan that allows you to preview your infrastructure changes before they're deployed. Once you verify the changes, you apply the execution plan to deploy the infrastructure.

Prerequisites

• An Azure account with an active subscription. You can create an account for free.

• Installation and configuration of Terraform.

Implement the Terraform code

Note

The sample code for this article is in the Azure Terraform GitHub repo. You can view the log file that contains the test results from current and previous versions of Terraform.

For more articles and sample code that show how to use Terraform to manage Azure resources, see the documentation page for Terraform on Azure.

1. Create a directory in which to test and run the sample Terraform code, and make it the current directory.

2. Create a file named main.tf and insert the following code:

   # Resource Group
   resource "azurerm_resource_group" "rg" {
     location = var.resource_group_location
     name     = "${random_pet.prefix.id}-rg"
   }
   
   # Virtual Network
   resource "azurerm_virtual_network" "my_terraform_network" {
     name                = "${random_pet.prefix.id}-vnet"
     address_space       = ["10.0.0.0/16"]
     location            = azurerm_resource_group.rg.location
     resource_group_name = azurerm_resource_group.rg.name
   }
   
   # Subnet 1
   resource "azurerm_subnet" "my_terraform_subnet_1" {
     name                 = "subnet-1"
     resource_group_name  = azurerm_resource_group.rg.name
     virtual_network_name = azurerm_virtual_network.my_terraform_network.name
     address_prefixes     = ["10.0.0.0/24"]
   }
   
   # Subnet 2
   resource "azurerm_subnet" "my_terraform_subnet_2" {
     name                 = "subnet-2"
     resource_group_name  = azurerm_resource_group.rg.name
     virtual_network_name = azurerm_virtual_network.my_terraform_network.name
     address_prefixes     = ["10.0.1.0/24"]
   }
   
   resource "random_pet" "prefix" {
     prefix = var.resource_group_name_prefix
     length = 1
   }
   

3. Create a file named outputs.tf and insert the following code:

   output "resource_group_name" {
     description = "The name of the created resource group."
     value       = azurerm_resource_group.rg.name
   }
   
   output "virtual_network_name" {
     description = "The name of the created virtual network."
     value       = azurerm_virtual_network.my_terraform_network.name
   }
   
   output "subnet_name_1" {
     description = "The name of the created subnet 1."
     value       = azurerm_subnet.my_terraform_subnet_1.name
   }
   
   output "subnet_name_2" {
     description = "The name of the created subnet 2."
     value       = azurerm_subnet.my_terraform_subnet_2.name
   }
   

4. Create a file named providers.tf and insert the following code:

   terraform {
     required_providers {
       azurerm = {
         source  = "hashicorp/azurerm"
         version = "~>3.0"
       }
       random = {
         source  = "hashicorp/random"
         version = "~>3.0"
       }
     }
   }
   
   provider "azurerm" {
     features {}
   }
   

5. Create a file named variables.tf and insert the following code:

   variable "resource_group_location" {
     type        = string
     default     = "eastus"
     description = "Location of the resource group."
   }
   
   variable "resource_group_name_prefix" {
     type        = string
     default     = "rg"
     description = "Prefix of the resource group name that's combined with a random ID so name is unique in your Azure subscription."
   }
   

Initialize Terraform

Run terraform init to initialize the Terraform deployment. This command downloads the Azure provider required to manage your Azure resources.

terraform init -upgrade

Key points:

• The -upgrade parameter upgrades the necessary provider plugins to the newest version that complies with the configuration's version constraints.

Create a Terraform execution plan

Run terraform plan to create an execution plan.

terraform plan -out main.tfplan

Key points:

• The terraform plan command creates an execution plan, but doesn't execute it. Instead, it determines what actions are necessary to create the configuration specified in your configuration files. This pattern allows you to verify whether the execution plan matches your expectations before making any changes to actual resources.
• The optional -out parameter allows you to specify an output file for the plan. Using the -out parameter ensures that the plan you reviewed is exactly what is applied.

Apply a Terraform execution plan

Run terraform apply to apply the execution plan to your cloud infrastructure.

terraform apply main.tfplan

Key points:

• The example terraform apply command assumes you previously ran terraform plan -out main.tfplan.
• If you specified a different filename for the -out parameter, use that same filename in the call to terraform apply.
• If you didn't use the -out parameter, call terraform apply without any parameters.

Verify the results

Azure CLI

1. Get the Azure resource group name:

   resource_group_name=$(terraform output -raw resource_group_name)
   

2. Get the virtual network name:

   virtual_network_name=$(terraform output -raw virtual_network_name)
   

3. Use az network vnet show to display the details of your newly created virtual network:

   az network vnet show \
       --resource-group $resource_group_name \
       --name $virtual_network_name
   

Clean up resources

When you no longer need the resources created via Terraform, do the following steps:

1. Run terraform plan and specify the destroy flag.

   terraform plan -destroy -out main.destroy.tfplan
   

   Key points:

   • The terraform plan command creates an execution plan, but doesn't execute it. Instead, it determines what actions are necessary to create the configuration specified in your configuration files. This pattern allows you to verify whether the execution plan matches your expectations before making any changes to actual resources.
   • The optional -out parameter allows you to specify an output file for the plan. Using the -out parameter ensures that the plan you reviewed is exactly what is applied.

2. Run terraform apply to apply the execution plan.

   terraform apply main.destroy.tfplan
   

Troubleshoot Terraform on Azure

For information about troubleshooting Terraform, see Troubleshoot common problems when using Terraform on Azure.

Next steps

Learn more about using Terraform on Azure