I have boot diagnostics for the VMs configured in Azure Storage Account. I would like to keep the retention policy of the boot diagnostics. How do I implement the Retention policy for the boot diagnostics files in Azure Storage account container ?

resource "azurerm_virtual_machine" "vm" {
  for_each            = var.vm
  name                = lower("vm${each.value.index}")
  resource_group_name = data.azurerm_resource_group.rg.name
  location            = data.azurerm_resource_group.rg.location
  zones               = ["${each.value.zone}"]
  vm_size             = var.vm_size

  network_interface_ids = [azurerm_network_interface.nic[each.key].id]

  storage_os_disk {
    name              = lower("vm${each.value.index}-os")
    caching           = "ReadWrite"
    create_option     = "FromImage"
    managed_disk_type = var.disk_type
  }

  os_profile {
.....
.
.
}

  boot_diagnostics {
    enabled     = true
    storage_uri = azurerm_storage_account.sa.primary_blob_endpoint
  }