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

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
      }
}