Terraform Module for a Private DNS Zone vNet Link

Summary: This is a terraform module that I use to deploy a link between a Private DNS zone and a virtual network in Azure.
Date: 8 February 2025

Read the post to learn more about private dns zone links and:

• How to deploy a private dns zone vnet link using a terraform module

Private DNS zone vNet links are a way to connect a private DNS zone to a virtual network in Azure. Without that links, resources within the virtual network cannot resolve resources within the private DNS zone.

The module for the Private DNS Zone vNet Link is defined over three files:

• main.tf: Contains the resources to create the private DNS Zone vNet link
• outputs.tf: Contains the output of the private DNS Zone vNet link
• variables.tf: Contains the input variables for the private DNS Zone vNet link

Notice the following:

• The DNS zone is a data source, not a resource. The DNS private zone already exists and is created outside of this module.
• Changes on tags are ignored to prevent unnecessary updates.

main.tf

data "azurerm_private_dns_zone" "private_dns_zone" {
  resource_group_name = var.resource_group_name
  name                = var.private_dns_zone_name
}
 
resource "azurerm_private_dns_zone_virtual_network_link" "link" {
  name                  = var.name
  resource_group_name   = var.resource_group_name
  private_dns_zone_name = data.azurerm_private_dns_zone.private_dns_zone.name
  virtual_network_id    = var.virtual_network_id
 
  lifecycle {
    ignore_changes = [
      tags
    ]
  }
}

outputs.tf

output "private_dns_zone_id" {
  description = "Specifies the resource id of the private dns zone"
  value       = data.azurerm_private_dns_zone.private_dns_zone.id
}

Note that most of the descriptions are copied from the terraform registry.

variables.tf

variable "name" {
  description = "(Required) The name of the Private DNS Zone Virtual Network Link. Changing this forces a new resource to be created."
  type        = string
}
 
variable "private_dns_zone_name" {
  description = "(Required) The name of the Private DNS zone (without a terminating dot). Changing this forces a new resource to be created."
  type        = string
}
 
variable "resource_group_name" {
  description = "(Required) Specifies the resource group name of the private dns zone"
  type        = string
}
 
variable "virtual_network_id" {
  description = "(Required) The ID of the Virtual Network that should be linked to the DNS Zone. Changing this forces a new resource to be created."
  type        = string
}