Create two web apps connected securely with Private Endpoint and VNet integration

This article illustrates an example use of Private Endpoint and regional VNet integration to connect two web apps (frontend and backend) securely with the following terraform configuration:

• Deploy a VNet
• Create the first subnet for the integration
• Create the second subnet for the private endpoint, you have to set a specific parameter to disable network policies
• Deploy one App Service plan of type Basic, Standard, PremiumV2, PremiumV3, IsolatedV2, Functions Premium (sometimes referred to as the Elastic Premium plan), required for Private Endpoint feature
• Create the frontend web app with specific app settings to consume the private DNS zone, more details
• Connect the frontend web app to the integration subnet
• Create the backend web app
• Create the DNS private zone with the name of the private link zone for web app privatelink.azurewebsites.net
• Link this zone to the VNet
• Create the private endpoint for the backend web app in the endpoint subnet, and register DNS names (website and SCM) in the previously created DNS private zone

How to use terraform in Azure

Browse to the Azure documentation to learn how to use terraform with Azure.

The complete terraform file

To use this file, replace the placeholders <unique-frontend-app-name> and <unique-backend-app-name> (app name is used to form a unique DNS name worldwide).

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

resource "azurerm_resource_group" "rg" {
  name     = "appservice-rg"
  location = "francecentral"
}

resource "azurerm_virtual_network" "vnet" {
  name                = "vnet"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  address_space       = ["10.0.0.0/16"]
}

resource "azurerm_subnet" "integrationsubnet" {
  name                 = "integrationsubnet"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.vnet.name
  address_prefixes     = ["10.0.1.0/24"]
  delegation {
    name = "delegation"
    service_delegation {
      name = "Microsoft.Web/serverFarms"
    }
  }
}

resource "azurerm_subnet" "endpointsubnet" {
  name                 = "endpointsubnet"
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.vnet.name
  address_prefixes     = ["10.0.2.0/24"]
  private_endpoint_network_policies_enabled = true
}

resource "azurerm_service_plan" "appserviceplan" {
  name                = "appserviceplan"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  os_type             = "Windows"
  sku_name            = "P1v2"
}

resource "azurerm_windows_web_app" "frontwebapp" {
  name                = "<unique-frontend-app-name>"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  service_plan_id = azurerm_service_plan.appserviceplan.id

  site_config {}
  app_settings = {
    "WEBSITE_DNS_SERVER": "168.63.129.16",
    "WEBSITE_VNET_ROUTE_ALL": "1"
  }
}

resource "azurerm_app_service_virtual_network_swift_connection" "vnetintegrationconnection" {
  app_service_id  = azurerm_windows_web_app.frontwebapp.id
  subnet_id       = azurerm_subnet.integrationsubnet.id
}

resource "azurerm_windows_web_app" "backwebapp" {
  name                = "<unique-backend-app-name>"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  service_plan_id = azurerm_service_plan.appserviceplan.id

  site_config {}
}

resource "azurerm_private_dns_zone" "dnsprivatezone" {
  name                = "privatelink.azurewebsites.net"
  resource_group_name = azurerm_resource_group.rg.name
}

resource "azurerm_private_dns_zone_virtual_network_link" "dnszonelink" {
  name = "dnszonelink"
  resource_group_name = azurerm_resource_group.rg.name
  private_dns_zone_name = azurerm_private_dns_zone.dnsprivatezone.name
  virtual_network_id = azurerm_virtual_network.vnet.id
}

resource "azurerm_private_endpoint" "privateendpoint" {
  name                = "backwebappprivateendpoint"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  subnet_id           = azurerm_subnet.endpointsubnet.id

  private_dns_zone_group {
    name = "privatednszonegroup"
    private_dns_zone_ids = [azurerm_private_dns_zone.dnsprivatezone.id]
  }

  private_service_connection {
    name = "privateendpointconnection"
    private_connection_resource_id = azurerm_windows_web_app.backwebapp.id
    subresource_names = ["sites"]
    is_manual_connection = false
  }
}

Next steps

Learn more about using Terraform in Azure