Quickstart: Create an Azure Firewall with multiple public IP addresses - Terraform

Article
02/23/2024

In this quickstart, you use Terraform to deploy an Azure Firewall with multiple public IP addresses from a public IP address prefix. The deployed firewall has NAT rule collection rules that allow RDP connections to two Windows Server 2019 virtual machines.

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.

For more information about Azure Firewall with multiple public IP addresses, see Deploy an Azure Firewall with multiple public IP addresses using Azure PowerShell.

In this article, you learn how to:

Create a random value (to be used in the resource group name) using random_pet

Create a random password for the Windows VM using random_password

Create an Azure resource group using azurerm_resource_group

Create an Azure public IP prefix using azurerm_public_ip_prefix

Create an Azure public IP using azurerm_public_ip

Create an Azure Virtual Network using azurerm_virtual_network

Create an Azure subnet using azurerm_subnet

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 a Network Interface and a Network Security Group using azurerm_network_interface_security_group_association

Create an Windows Virtual Machine using azurerm_windows_virtual_machine

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 route table using azurerm_route_table

Create an association between the route table and the subnet using - azurerm_subnet_route_table_association

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 {
    virtual_machine {
      delete_os_disk_on_deletion     = true
      skip_shutdown_and_force_delete = true
    }
  }
}

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

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

resource "random_password" "password" {
  count       = 2
  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_prefix" "pip_prefix" {
  name                = "pip-prefix"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  sku                 = "Standard"
  prefix_length       = 31
}

resource "azurerm_public_ip" "pip_azfw" {
  name                = "pip-azfw"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  sku                 = "Standard"
  allocation_method   = "Static"
  public_ip_prefix_id = azurerm_public_ip_prefix.pip_prefix.id
}

resource "azurerm_public_ip" "pip_azfw_2" {
  name                = "pip-azfw-1"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  sku                 = "Standard"
  allocation_method   = "Static"
  public_ip_prefix_id = azurerm_public_ip_prefix.pip_prefix.id
}

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" "backend_subnet" {
  name                 = "subnet-backend"
  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_network_interface" "backend_nic" {
  count               = 2
  name                = "nic-backend-${count.index + 1}"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name

  ip_configuration {
    name                          = "ipconfig-backend-${count.index + 1}"
    subnet_id                     = azurerm_subnet.backend_subnet.id
    private_ip_address_allocation = "Dynamic"
  }
}

resource "azurerm_network_security_group" "backend_nsg" {
  name                = "nsg-backend"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  security_rule {
    name                       = "RDP"
    priority                   = 300
    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_backend_nsg_association" {
  count                     = 2
  network_interface_id      = azurerm_network_interface.backend_nic[count.index].id
  network_security_group_id = azurerm_network_security_group.backend_nsg.id
}

resource "azurerm_windows_virtual_machine" "vm_backend" {
  count                 = 2
  name                  = "vm-backend-${count.index + 1}"
  resource_group_name   = azurerm_resource_group.rg.name
  location              = azurerm_resource_group.rg.location
  size                  = var.virtual_machine_size
  admin_username        = var.admin_username
  admin_password        = random_password.password[count.index].result
  network_interface_ids = [azurerm_network_interface.backend_nic[count.index].id]
  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }
  source_image_reference {
    publisher = "MicrosoftWindowsServer"
    offer     = "WindowsServer"
    sku       = "2019-Datacenter"
    version   = "latest"
  }
}

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" "policy_rule_collection_group" {
  name               = "RuleCollectionGroup"
  firewall_policy_id = azurerm_firewall_policy.azfw_policy.id
  priority           = 300
  application_rule_collection {
    name     = "web"
    priority = 100
    action   = "Allow"
    rule {
      name = "wan-address"
      protocols {
        type = "Http"
        port = 80
      }
      protocols {
        type = "Https"
        port = 443
      }
      destination_fqdns = ["getmywanip.com"]
      source_addresses  = ["*"]
    }
    rule {
      name = "google"
      protocols {
        type = "Http"
        port = 80
      }
      protocols {
        type = "Https"
        port = 443
      }
      destination_fqdns = ["www.google.com"]
      source_addresses  = ["10.10.1.0/24"]
    }
    rule {
      name = "wupdate"
      protocols {
        type = "Http"
        port = 80
      }
      protocols {
        type = "Https"
        port = 443
      }
      destination_fqdn_tags = ["WindowsUpdate"]
      source_addresses      = ["*"]
    }
  }
  nat_rule_collection {
    name     = "Coll-01"
    action   = "Dnat"
    priority = 200
    rule {
      name                = "rdp-01"
      protocols           = ["TCP"]
      translated_address  = "10.10.1.4"
      translated_port     = "3389"
      source_addresses    = ["*"]
      destination_address = azurerm_public_ip.pip_azfw.ip_address
      destination_ports   = ["3389"]
    }
    rule {
      name                = "rdp-02"
      protocols           = ["TCP"]
      translated_address  = "10.10.1.5"
      translated_port     = "3389"
      source_addresses    = ["*"]
      destination_address = azurerm_public_ip.pip_azfw.ip_address
      destination_ports   = ["3389"]
    }
  }
}

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
  ip_configuration {
    name                 = "azfw-ipconfig"
    subnet_id            = azurerm_subnet.azfw_subnet.id
    public_ip_address_id = azurerm_public_ip.pip_azfw.id
  }
  ip_configuration {
    name                 = "azfw-ipconfig-2"
    public_ip_address_id = azurerm_public_ip.pip_azfw_2.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                   = "azfw"
    address_prefix         = "0.0.0.0/0"
    next_hop_type          = "VirtualAppliance"
    next_hop_in_ip_address = "10.10.0.4"
  }
}

resource "azurerm_subnet_route_table_association" "jump_subnet_rt_association" {
  subnet_id      = azurerm_subnet.backend_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 "backend_admin_password" {
  sensitive = true
  value     = azurerm_windows_virtual_machine.vm_backend[*].admin_password
}

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)

Run az network ip-group list to display the two new IP Groups.

az network ip-group list --resource-group $resource_group_name

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

Tutorial: Deploy and configure Azure Firewall in a hybrid network using the Azure portal

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Quickstart: Create an Azure Firewall with multiple public IP addresses - 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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