terraform azure public ip and public ip prefix

Question

I'm trying to create an Azure public IP prefix (/30) then assign a public IP from the prefix (4 times) then assign them as outputs to use in a separate module later. I would like to assign one of the IPs in the NIC listed, then "save" the other 3 as an output for later use. I am however getting the following error:

│ The "count" object can only be used in "module", "resource", and "data"
│ blocks, and only when the "count" argument is set.

I am also struggling with the syntax in how to reference each IP as an output (I've included the outputs.tf below but know the syntax is wrong):

main.tf

resource "azurerm_public_ip_prefix" "ipprefix" {
  name                    = "tempprefixname"
  location                = var.rglocation
  resource_group_name     = var.rgname

  prefix_length = 30
}

resource "azurerm_public_ip" "publicip" {
  count                 = 4
  name                  = "${var.publicipname}-${count.index}"
  location              = var.rglocation
  resource_group_name   = var.rgname
  allocation_method     = "Static"
  sku                   = "Basic"
  public_ip_prefix_id   = azurerm_public_ip_prefix.ipprefix.id
}

resource "azurerm_network_interface" "nic" {
  name                    = var.nicname
  location                = var.rglocation
  resource_group_name     = var.rgname

  ip_configuration {
    name                          = var.ipconfigname
    subnet_id                     = azurerm_subnet.subnet.id
    private_ip_address_allocation = "Dynamic"
    public_ip_address_id          = azurerm_public_ip.publicip[count.index].id
  }
}

outputs.tf

output "publicipoutput1" {
    value = azurerm_public_ip.publicip.ip_address[count.1]
}
output "publicipoutput2" {
    value = azurerm_public_ip.publicip.ip_address[count.2]
}
output "publicipoutput3" {
    value = azurerm_public_ip.publicip.ip_address[count.3]
}
output "publicipoutput4" {
    value = azurerm_public_ip.publicip.ip_address[count.4]
}

Answer 1

When you start using count , you have to use it in all places where you reference any other resource created with count [1]. So, if you used count in azurerm_public_ip , you have to use count in azurerm.network_interface as well and not just count.index :

resource "azurerm_network_interface" "nic" {
  count               = 4
  name                = var.nicname
  location            = var.rglocation
  resource_group_name = var.rgname

  ip_configuration {
    name                          = var.ipconfigname
    subnet_id                     = azurerm_subnet.subnet.id
    private_ip_address_allocation = "Dynamic"
    public_ip_address_id          = azurerm_public_ip.publicip[count.index].id
  }
}

As you can see from the error, output cannot use count , but you can select all of the values by using the splat expression [2]:

output "public_ip_addresses" {
    value = [ azurerm_public_ip.publicip[*].ip_address ]
}

---

[1] https://www.terraform.io/language/meta-arguments/count

[2] https://www.terraform.io/language/expressions/splat