Lifecycle issue

Terraform
1

Hello, Please suggest how to fix this issue.
My Code:
lifecycle {
prevent_destroy = var.instance_name[count.index] == backend ? true : false
}

Getting error like below:

Error: Variables not allowed
│
│ on azurevm.tf line 45, in resource “azurerm_virtual_machine” “main”:
│ 45: prevent_destroy = var.instance_name[count.index] == backend ? true : false
│
│ Variables may not be used here.
╵
╷
│ Error: Unsuitable value type
│
│ on azurevm.tf line 45, in resource “azurerm_virtual_machine” “main”:
│ 45: prevent_destroy = var.instance_name[count.index] == backend ? true : false
│
│ Unsuitable value: value must be known
╵
╷
│ Error: Variables not allowed
│
│ on azurevm.tf line 45, in resource “azurerm_virtual_machine” “main”:
│ 45: prevent_destroy = var.instance_name[count.index] == backend ? true : false
│
│ Variables may not be used here.
╵
╷
│ Error: Variables not allowed
│
│ on azurevm.tf line 45, in resource “azurerm_virtual_machine” “main”:
│ 45: prevent_destroy = var.instance_name[count.index] == backend ? true : false
│
│ Variables may not be used here.

2

Terraform is telling you that it does not allow prevent_destroy to contain variables. It just doesn’t support it.