How to update Azure's load balancer from basic to standard in Terraform?

I got a warning in Azure Portal that my load balancer "is on Basic SKU which will be retired on 30 September 2025. Learn more about Standard SKU and migration steps."

I have been trying to find without success how to upgrade my Terraform code.

This is my Terraform:

resource "azurerm_lb" "foo" {
  name = "foo-${var.URL_NAME}"

  frontend_ip_configuration {
    name                 = "PublicIPAddress"
    public_ip_address_id = azurerm_public_ip.foo_lb_ip.id
  }

   location            = var.AZURE_REGION
  resource_group_name = data.azurerm_resource_group.foo.name
}

resource "azurerm_lb_backend_address_pool" "foo" {
  name            = "BackEndAddressPool"
  loadbalancer_id = azurerm_lb.foo.id
}

resource "azurerm_network_interface_backend_address_pool_association" "foo" {
  count                   = var.NUMBER_OF_VMS
  backend_address_pool_id = azurerm_lb_backend_address_pool.foo.id
  ip_configuration_name   = "internal"
  network_interface_id    = azurerm_network_interface.foo[count.index].id
}

resource "azurerm_lb_probe" "foo" {
  name            = "foo-${var.URL_NAME}"
  protocol        = "Tcp"
  port            = 9999
  loadbalancer_id = azurerm_lb.foo.id
}

resource "azurerm_lb_rule" "foo" {
  name                           = "foo-${var.URL_NAME}"
  protocol                       = "Tcp"
  frontend_port                  = 9999
  backend_port                   = 9999
  frontend_ip_configuration_name = azurerm_lb.foo.frontend_ip_configuration[0].name
  loadbalancer_id                = azurerm_lb.foo.id
  backend_address_pool_ids       = [azurerm_lb_backend_address_pool.foo.id]
}

resource "azurerm_public_ip" "foo_lb_ip" {
  name                = "foo-lb-ip"
  allocation_method   = "Dynamic"
  location            = var.AZURE_REGION
  resource_group_name = data.azurerm_resource_group.foo.name
}

How to update Azure's load balancer from basic to standard in Terraform?

To update Azure's Load Balancer from Basic to Standard, you need to change the LB SKU to 'Standard' and ensure that the public IP SKU is also 'Standard'. Only then will the Load Balancer be updated to Standard.

Note: If you cannot afford downtime for the resource, you can use create_before_destroy = true. This feature will create the new resource first and ensure it is fully operational before destroying the old resource. This is crucial for minimizing downtime between resources. However, make sure to use a new name for the resource when you use this feature.

lifecycle {
    create_before_destroy = true
  }

Here is Terraform code to update Azure Load balancer SKU to Standard

provider "azurerm" {
  features {}
}

resource "azurerm_resource_group" "example" {
  name     = "network-RG2"
  location = "West Europe"
 
}

resource "azurerm_virtual_network" "example" {
  name                = "sample-network1"
  address_space       = ["10.0.0.0/16"]
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
}

resource "azurerm_subnet" "example" {
  name                 = "internal1"
  resource_group_name  = azurerm_resource_group.example.name
  virtual_network_name = azurerm_virtual_network.example.name
  address_prefixes     = ["10.0.2.0/24"]
}

resource "azurerm_public_ip" "example" {
  name                = "venkat-pip1"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
  allocation_method   = "Static"
  sku                 = "Standard"
}

resource "azurerm_lb" "example" {
  name                = "venkat-lb1"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
  sku                 = "Standard"

  frontend_ip_configuration {
    name                 = "primary"
    public_ip_address_id = azurerm_public_ip.example.id
  }
depends_on = [ azurerm_public_ip.example ]
}

resource "azurerm_lb_backend_address_pool" "example" {
  loadbalancer_id = azurerm_lb.example.id
  name            = "acctestpool1"
}

resource "azurerm_network_interface" "example" {
  name                = "venkat-nic1"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name

  ip_configuration {
    name                          = "venkattestconfig1"
    subnet_id                     = azurerm_subnet.example.id
    private_ip_address_allocation = "Dynamic"
  }

}
resource "azurerm_network_interface_backend_address_pool_association" "example" {
  network_interface_id    = azurerm_network_interface.example.id
  ip_configuration_name   = "venkattestconfig1"
  backend_address_pool_id = azurerm_lb_backend_address_pool.example.id
}

Terraform apply:

After executing the terraform script, The Azure Load balancer SKU has been changed to Standard

Alternatively, you can also use PowerShell code in terraform by using null resource block to upgrade load balancer sku to Standard. below is the terraform code with null resource

resource "null_resource" "powershell" {
  triggers = {
    }

provisioner "local-exec" {
        command = <<-EOT
        Start-AzBasicLoadBalancerUpgrade -ResourceGroupName <loadBalancerRGName> -BasicLoadBalancerName <basicLBName> -validateScenarioOnly
        EOT
      }
}