Variable in terraform resource referance

Question

I'm trying create a resource in terraform that will create a number of subnets based on a list variable.

I'm having trouble with references to existing resources. For example in the following code network_security_group_id is hardcoded to azurerm_network_security_group.k8s.id:

variable "resources_large" {
    description = "List of Large Networks" 
    default = [
      "k8s",
      "storm"
    ]
}

resource "azurerm_subnet" "large" {
  name                      = "ue-${var.environment}-${var.resources_large[count.index]}-subnet-${replace("${cidrsubnet("${local.subnet_ranges["large"]}", "${var.newbit_size["large"] }", count.index )}", "/[./]/", "-"  ) }"
  resource_group_name       = "ue-${var.environment}-${var.resources_large[count.index]}-rg"
  virtual_network_name      = "${azurerm_virtual_network.dev.name}"
  address_prefix            = "${cidrsubnet("${local.subnet_ranges["large"]}", "${var.newbit_size["large"] }", count.index )}"
  network_security_group_id = "${azurerm_network_security_group.k8s.id}"

  count  = "${length(var.resources_large)}"

  depends_on = ["azurerm_virtual_network.dev"]
}

This needs to reference existing security groups based on the name in the resources_large list. What I'd like to have is something which looks likes this:

network_security_group_id = "${azurerm_network_security_group.${var.resources_large[count.index]}.id}"

Which doesn't work, I'm guessing due to the lack of variable interpolation support.

Is there any way to reference other resources based on variable?

Giulio Vian · Accepted Answer · 2018-01-16 16:50:18Z

1

Maybe something like this

locals {
  sgs = {
    k8s = "${azurerm_network_security_group.k8s.id}"
    storm = "${azurerm_network_security_group.storm.id}"
  }
}

...

network_security_group_id = "${lookup( locals.sgs, var.resources_large[count.index])}"

may work.

If you create the SG using the same counter, it can be just

network_security_group_id = "${element(azurerm_network_security_group.*.id, count.index)}"

HTH

edited Jan 16, 2018 at 16:50

answered Jan 16, 2018 at 14:22

Giulio Vian

8,3532 gold badges36 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

ydaetskcoR Over a year ago

Except they didn't create their network security group in a loop by the looks of it so that won't work.

Setanta Over a year ago

Just to point out, we actually will be creating the security groups in a loop, just haven't gotten to that part yet. I will test out the above.

Giulio Vian Over a year ago

I edited again to save the initial answer, in case someone needs it

Collectives™ on Stack Overflow

Variable in terraform resource referance

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related