Quickstart: Configure an Azure virtual network gateway with Terraform

In this quickstart, you use Terraform to create an Azure ExpressRoute circuit with Equinix as the service provider. The circuit uses a Standard SKU with a bandwidth of 50 Mbps and the peering location of Washington, D.C. Private peering is enabled with a primary and secondary subnet of 192.168.10.16/30 and 192.168.10.20/30, respectively. The script also creates a virtual network and a HighPerformance ExpressRoute gateway.

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.

In this article, you learn how to:

• Create an Azure resource group with a unique name.
• Create a virtual network with a subnet for the gateway.
• Create a public IP for the gateway.
• Create an ExpressRoute circuit and configure private peering.
• Output the resource group name, ExpressRoute circuit ID, gateway name, gateway IP, and the service key.

Prerequisites

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

• Install and configure Terraform.

Implement the Terraform code

Note

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

See more articles and sample code showing how to use Terraform to manage Azure resources.

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:

   # Create Resource Group
   resource "random_pet" "rg_name" {
     prefix = var.resource_group_name_prefix
   }
   
   resource "azurerm_resource_group" "rg" {
     location = var.resource_group_location
     name     = random_pet.rg_name.id
   }
   
   # Random String for unique naming
   resource "random_string" "name" {
     length  = 8
     special = false
     upper   = false
     lower   = true
     numeric = false
   }
   
   # Create Virtual Network
   resource "azurerm_virtual_network" "vnet" {
     name                = "vnet-${random_string.name.result}"
     address_space       = ["10.0.0.0/16"]
     location            = azurerm_resource_group.rg.location
     resource_group_name = azurerm_resource_group.rg.name
   }
   
   # Create Subnet for Gateway
   resource "azurerm_subnet" "gateway_subnet" {
     name                 = "GatewaySubnet"
     resource_group_name  = azurerm_resource_group.rg.name
     virtual_network_name = azurerm_virtual_network.vnet.name
     address_prefixes     = ["10.0.0.0/24"]
   }
   
   # Create Public IP for Gateway
   resource "azurerm_public_ip" "gateway_ip" {
     name                 = "pip-${random_string.name.result}"
     location            = azurerm_resource_group.rg.location
     resource_group_name = azurerm_resource_group.rg.name
     allocation_method   = "Static"
     sku                 = "Standard"
   }
   
   # Create ExpressRoute Gateway
   resource "azurerm_virtual_network_gateway" "gateway" {
     name                 = "gateway-${random_string.name.result}"
     location            = azurerm_resource_group.rg.location
     resource_group_name = azurerm_resource_group.rg.name
     type                = "ExpressRoute"
     vpn_type            = "RouteBased"
     active_active       = false
     enable_bgp          = false
     sku                 = "HighPerformance"
   
     ip_configuration {
       name                 = "vnetGatewayConfig"
       public_ip_address_id = azurerm_public_ip.gateway_ip.id
       subnet_id            = azurerm_subnet.gateway_subnet.id
     }
   }
   
   # Create ExpressRoute Circuit
   resource "azurerm_express_route_circuit" "circuit" {
     name                 = "erc-${random_string.name.result}"
     resource_group_name   = azurerm_resource_group.rg.name
     location              = azurerm_resource_group.rg.location
     service_provider_name = "Equinix"
     peering_location      = "Washington DC"
     bandwidth_in_mbps     = 50
     sku {
       tier   = "Standard"
       family = "MeteredData"
     }
   }
   
   # Create ExpressRoute Circuit Peering
   resource "azurerm_express_route_circuit_peering" "private" {
     peering_type                  = "AzurePrivatePeering"
     express_route_circuit_name    = azurerm_express_route_circuit.circuit.name
     resource_group_name           = azurerm_resource_group.rg.name
     primary_peer_address_prefix   = "192.168.10.16/30"
     secondary_peer_address_prefix = "192.168.10.20/30"
     vlan_id                       = 200
     peer_asn                      = 65001 # Provide a valid private ASN here 
   }
   

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

   output "resource_group_name" {
     value = azurerm_resource_group.rg.name
   }
   
   output "express_route_circuit_id" {
     value = azurerm_express_route_circuit.circuit.id
   }
   
   output "gateway_name" {
     value = azurerm_virtual_network_gateway.gateway.name
   }
   
   output "gateway_ip" {
     value = azurerm_public_ip.gateway_ip.ip_address
   }
   
   output "service_key" {
     value     = azurerm_express_route_circuit.circuit.service_key
     sensitive = true
   }
   

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 gateway name.

   gateway_name=$(terraform output -raw gateway_name)
   

3. Run az network vnet-gateway show to view the Azure virtual network gateway.

   az network vnet-gateway show --name $gateway_name --resource-group $resource_group_name
   

Azure PowerShell

1. Get the Azure resource group name.

   $resource_group_name=$(terraform output -raw resource_group_name)
   

2. Get the gateway name.

   $gateway_name=$(terraform output -raw gateway_name)
   

3. Run Get-AzVirtualNetworkGateway to view the Azure virtual network gateway.

   Get-AzVirtualNetworkGateway -Name $gateway_name -ResourceGroupName $resource_group_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

Troubleshoot common problems when using Terraform on Azure.

Next steps

See more articles about Azure virtual network gateway.

To learn how to link a virtual network to a circuit, continue to the ExpressRoute tutorials.

ExpressRoute tutorials