Quickstart: Deploy Azure Firewall with Availability Zones - Terraform

Article
10/18/2023

In this quickstart, you use Terraform to deploy an Azure Firewall in three Availability Zones.

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.

The Terraform configuration creates a test network environment with a firewall. The network has one virtual network (VNet) with three subnets: AzureFirewallSubnet, subnet-server, and subnet-jump. The subnet-server and subnet-jump subnet each have a single two-core Windows Server virtual machine.

The firewall is in the AzureFirewallSubnet subnet and has an application rule collection with a single rule that allows access to www.microsoft.com.

A user-defined route points network traffic from the subnet-server subnet through the firewall where the firewall rules are applied.

For more information about Azure Firewall, see Deploy and configure Azure Firewall using the Azure portal.

In this article, you learn how to:

Create a random value (to be used in the resource group name) using random_pet
Create an Azure resource group using azurerm_resource_group
Create an Azure Virtual Network using azurerm_virtual_network
Create three Azure subnets using azurerm_subnet
Create an Azure public IP using azurerm_public_ip
Create an Azure Firewall Policy using azurerm_firewall_policy
Create an Azure Firewall Policy Rule Collection Group using azurerm_firewall_policy_rule_collection_group
Create an Azure Firewall using azurerm_firewall
Create a network interface using azurerm_network_interface
Create a network security group (to contain a list of network security rules) using azurerm_network_security_group
Create an association between the network interface and the network security group using - azurerm_network_interface_security_group_association
Create a route table using azurerm_route_table
Create an association between the route table and the subnet using - azurerm_subnet_route_table_association
Create a random value (to be used as the storage name) using random_string
Create a storage account using azurerm_storage_account
Create a random password for the Windows VM using random_password
Create an Azure Windows Virtual Machine using azurerm_windows_virtual_machine

Prerequisites

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

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

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 {}
}

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

resource "random_pet" "rg_name" {
  prefix = var.resource_group_name_prefix
}

resource "random_string" "storage_account_name" {
  length  = 8
  lower   = true
  numeric = false
  special = false
  upper   = false
}

resource "random_password" "password" {
  length      = 20
  min_lower   = 1
  min_upper   = 1
  min_numeric = 1
  min_special = 1
  special     = true
}

resource "azurerm_resource_group" "rg" {
  name     = random_pet.rg_name.id
  location = var.resource_group_location
}

resource "azurerm_public_ip" "pip_azfw" {
  name                = "pip-azfw"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  allocation_method   = "Static"
  sku                 = "Standard"
  zones               = ["1", "2", "3"]
}

resource "azurerm_storage_account" "sa" {
  name                     = random_string.storage_account_name.result
  resource_group_name      = azurerm_resource_group.rg.name
  location                 = azurerm_resource_group.rg.location
  account_tier             = "Standard"
  account_replication_type = "LRS"
  account_kind             = "StorageV2"
}

resource "azurerm_virtual_network" "azfw_vnet" {
  name                = "azfw-vnet"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  address_space       = ["10.10.0.0/16"]
}

resource "azurerm_subnet" "azfw_subnet" {
  name                 = "AzureFirewallSubnet"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.azfw_vnet.name
  address_prefixes     = ["10.10.0.0/26"]
}

resource "azurerm_subnet" "server_subnet" {
  name                 = "subnet-server"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.azfw_vnet.name
  address_prefixes     = ["10.10.1.0/24"]
}

resource "azurerm_subnet" "jump_subnet" {
  name                 = "subnet-jump"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.azfw_vnet.name
  address_prefixes     = ["10.10.2.0/24"]
}

resource "azurerm_public_ip" "vm_jump_pip" {
  name                = "pip-jump"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  allocation_method   = "Static"
  sku                 = "Standard"
}

resource "azurerm_network_interface" "vm_server_nic" {
  name                = "nic-server"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name

  ip_configuration {
    name                          = "ipconfig-workload"
    subnet_id                     = azurerm_subnet.server_subnet.id
    private_ip_address_allocation = "Dynamic"
  }
}

resource "azurerm_network_interface" "vm_jump_nic" {
  name                = "nic-jump"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name

  ip_configuration {
    name                          = "ipconfig-jump"
    subnet_id                     = azurerm_subnet.jump_subnet.id
    private_ip_address_allocation = "Dynamic"
    public_ip_address_id          = azurerm_public_ip.vm_jump_pip.id
  }
}

resource "azurerm_network_security_group" "vm_server_nsg" {
  name                = "nsg-server"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
}

resource "azurerm_network_security_group" "vm_jump_nsg" {
  name                = "nsg-jump"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  security_rule {
    name                       = "Allow-TCP"
    priority                   = 1000
    direction                  = "Inbound"
    access                     = "Allow"
    protocol                   = "Tcp"
    source_port_range          = "*"
    destination_port_range     = "3389"
    source_address_prefix      = "*"
    destination_address_prefix = "*"
  }
}

resource "azurerm_network_interface_security_group_association" "vm_server_nsg_association" {
  network_interface_id      = azurerm_network_interface.vm_server_nic.id
  network_security_group_id = azurerm_network_security_group.vm_server_nsg.id
}

resource "azurerm_network_interface_security_group_association" "vm_jump_nsg_association" {
  network_interface_id      = azurerm_network_interface.vm_jump_nic.id
  network_security_group_id = azurerm_network_security_group.vm_jump_nsg.id
}

resource "azurerm_windows_virtual_machine" "vm_server" {
  name                  = "server-vm"
  resource_group_name   = azurerm_resource_group.rg.name
  location              = azurerm_resource_group.rg.location
  computer_name         = "server"
  size                  = var.virtual_machine_size
  admin_username        = var.admin_username
  admin_password        = random_password.password.result
  network_interface_ids = [azurerm_network_interface.vm_server_nic.id]
  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
    disk_size_gb         = "128"
  }
  source_image_reference {
    publisher = "MicrosoftWindowsServer"
    offer     = "WindowsServer"
    sku       = "2019-Datacenter"
    version   = "latest"
  }
  boot_diagnostics {
    storage_account_uri = azurerm_storage_account.sa.primary_blob_endpoint
  }
}

resource "azurerm_windows_virtual_machine" "vm_jump" {
  name                  = "jump-vm"
  resource_group_name   = azurerm_resource_group.rg.name
  location              = azurerm_resource_group.rg.location
  computer_name         = "jumpbox"
  size                  = var.virtual_machine_size
  admin_username        = var.admin_username
  admin_password        = random_password.password.result
  network_interface_ids = [azurerm_network_interface.vm_jump_nic.id]
  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
    disk_size_gb         = "128"
  }
  source_image_reference {
    publisher = "MicrosoftWindowsServer"
    offer     = "WindowsServer"
    sku       = "2019-Datacenter"
    version   = "latest"
  }
  boot_diagnostics {
    storage_account_uri = azurerm_storage_account.sa.primary_blob_endpoint
  }
}

resource "azurerm_firewall_policy" "azfw_policy" {
  name                     = "azfw-policy"
  resource_group_name      = azurerm_resource_group.rg.name
  location                 = azurerm_resource_group.rg.location
  sku                      = var.firewall_sku_tier
  threat_intelligence_mode = "Alert"
}

resource "azurerm_firewall_policy_rule_collection_group" "prcg" {
  name               = "prcg"
  firewall_policy_id = azurerm_firewall_policy.azfw_policy.id
  priority           = 300
  application_rule_collection {
    name     = "appRc1"
    priority = 101
    action   = "Allow"
    rule {
      name = "appRule1"
      protocols {
        type = "Http"
        port = 80
      }
      protocols {
        type = "Https"
        port = 443
      }
      destination_fqdns = ["www.microsoft.com"]
      source_addresses  = ["10.10.1.0/24"]
    }
  }
  network_rule_collection {
    name     = "netRc1"
    priority = 200
    action   = "Allow"
    rule {
      name                  = "netRule1"
      protocols             = ["TCP"]
      source_addresses      = ["10.10.1.0/24"]
      destination_addresses = ["*"]
      destination_ports     = ["8000", "8999"]
    }
  }
}

resource "azurerm_firewall" "fw" {
  name                = "azfw"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  sku_name            = "AZFW_VNet"
  sku_tier            = var.firewall_sku_tier
  zones               = ["1", "2", "3"]
  ip_configuration {
    name                 = "azfw-ipconfig"
    subnet_id            = azurerm_subnet.azfw_subnet.id
    public_ip_address_id = azurerm_public_ip.pip_azfw.id
  }
  firewall_policy_id = azurerm_firewall_policy.azfw_policy.id
}

resource "azurerm_route_table" "rt" {
  name                          = "rt-azfw-eus"
  location                      = azurerm_resource_group.rg.location
  resource_group_name           = azurerm_resource_group.rg.name
  disable_bgp_route_propagation = false
  route {
    name                   = "azfwDefaultRoute"
    address_prefix         = "0.0.0.0/0"
    next_hop_type          = "VirtualAppliance"
    next_hop_in_ip_address = azurerm_firewall.fw.ip_configuration[0].private_ip_address
  }
}

resource "azurerm_subnet_route_table_association" "jump_subnet_rt_association" {
  subnet_id      = azurerm_subnet.server_subnet.id
  route_table_id = azurerm_route_table.rt.id
}

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

variable "resource_group_location" {
  type        = string
  description = "Location for all resources."
  default     = "eastus"
}

variable "resource_group_name_prefix" {
  type        = string
  description = "Prefix for the Resource Group Name that's combined with a random id so name is unique in your Azure subcription."
  default     = "rg"
}

variable "firewall_sku_tier" {
  type        = string
  description = "Firewall SKU."
  default     = "Premium" # Valid values are Standard and Premium
  validation {
    condition     = contains(["Standard", "Premium"], var.firewall_sku_tier)
    error_message = "The SKU must be one of the following: Standard, Premium"
  }
}

variable "virtual_machine_size" {
  type        = string
  description = "Size of the virtual machine."
  default     = "Standard_D2_v3"
}

variable "admin_username" {
  type        = string
  description = "Value of the admin username."
  default     = "azureuser"
}

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

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

output "firewall_name" {
  value = azurerm_firewall.fw.name
}

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

Get the Azure resource group name.

resource_group_name=$(terraform output -raw resource_group_name)

Get the firewall name.

firewall_name=$(terraform output -raw firewall_name)

Run az network firewall show with a JMESPath query to display the availability zones for the firewall.

az network firewall show --name $firewall_name --resource-group $resource_group_name --query "{Zones:zones"}

Clean up resources

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

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.
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

Next, you can monitor the Azure Firewall logs.

Tutorial: Monitor Azure Firewall logs

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Quickstart: Deploy Azure Firewall with Availability Zones - Terraform

Prerequisites

Implement the Terraform code

Initialize Terraform

Create a Terraform execution plan

Apply a Terraform execution plan

Verify the results

Clean up resources

Troubleshoot Terraform on Azure

Next steps

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