Reference exact resource created with for_each

Terraform
1

Hello!
I need to reference the exact resource created with for_each loop.
So, this code works fine:

variable "natgw" {
  type = object({
    azs  = set(string)
    zone = string
  })

  default = {
    zone = "1"
    azs  = ["1", "2", "3"]
  }
}

resource "azurerm_public_ip" "pip" {
  for_each            = var.natgw.azs
...
  zones               = [each.value]
}

resource "azurerm_nat_gateway" "natgateway" {
  for_each                = var.natgw.azs
....
  zones                   = [each.value]
}

resource "azurerm_nat_gateway_public_ip_association" "pip_association" {
  for_each             = var.natgw.azs
  nat_gateway_id       = azurerm_nat_gateway.natgateway[each.value].id
  public_ip_address_id = azurerm_public_ip.pip[each.value].id
}

resource "azurerm_subnet_nat_gateway_association" "subnet_association" {
  subnet_id      = azurerm_subnet.exact_subnet.id
  nat_gateway_id = azurerm_nat_gateway.natgateway[var.natgw.zone].id
}

Until I change var.natgw.zone

  default = {
    zone = "2"
    azs  = ["1", "2", "3"]
  }

or just put 2 as index:

 nat_gateway_id = azurerm_nat_gateway.natgateway[2].id

I receive an error:

│ Error: Invalid index
│ 
│"azurerm_subnet_nat_gateway_association" "subnet_association":
│     nat_gateway_id = azurerm_nat_gateway.natgateway[var.natgw.zone].id
│     ├────────────────
│     │ azurerm_nat_gateway.natgateway is object with 1 attribute "1"
│     │ var.natgw.zone is "2"
│ 
│ The given key does not identify an element in this collection value.

terraform state list | grep azurerm_nat_gateway.natgateway                                                                                                                                                    
module.vnet.azurerm_nat_gateway.natgateway["1"]
module.vnet.azurerm_nat_gateway.natgateway["2"]
module.vnet.azurerm_nat_gateway.natgateway["3"]

It looks a bit weird to me since azurerm_nat_gateway_public_ip_association doesn’t through an error that it can’t find indexes.
Or I can’t reference in such a way and need to add some kind of loop there also?
thanks in advance

2

This doesn’t make sense… but I can see that in some places you have var.nat_gateway and in others var.natgw so I think you have “simplified” your code prior to posting, and in doing so hidden information that is necessary to understand the problem.

3

well, yes. I removed all unneeded staff like skus, resource_groups, region and so on.
There were also some conditions, but at the end 3 natgateways were created, and I can reference all of them with for_each in the other resource, but can’t the exact one.
I’ve edited error with correct var reference, apology

4

In the process of simplifying your configuration, you have removed whatever the error is.

I can state that with confidence, because I took your exact shown config, converted it all into null_resources so I could run it without Azure, and tested it working just fine.

variable "natgw" {
  type = object({
    azs  = set(string)
    zone = string
  })

  default = {
    zone = "2"
    azs  = ["1", "2", "3"]
  }
}

resource "null_resource" "pip" {
  for_each = var.natgw.azs
  triggers = {
    zones = jsonencode([each.value])
  }
}

resource "null_resource" "natgateway" {
  for_each = var.natgw.azs
  triggers = {
    zones = jsonencode([each.value])
  }
}

resource "null_resource" "pip_association" {
  for_each = var.natgw.azs
  triggers = {
    nat_gateway_id       = null_resource.natgateway[each.value].id
    public_ip_address_id = null_resource.pip[each.value].id
  }
}

resource "null_resource" "subnet_association" {
  triggers = {
    subnet_id      = "placeholder"
    nat_gateway_id = null_resource.natgateway[var.natgw.zone].id
  }
}