Terraform - conditionally creating a resource within a loop

Question

Is it possible to combine resource creation with a loop (using count) and conditionally skip some resources based on the value of a map?

I know we can do these things separately:

use count to create resources in a loop.
use the variable/count workaround (in place of an 'if' statement) to conditional create a resource

To illustrate lets say I have a list of maps:

variable "resources" {
  type = "list"
  default = [
    {
      name = "kafka"
      createStorage = true
    },
    {
      name = "elastic"
      createStorage = false
    },
    {
      name = "galera"
      createStorage = true
    }
  ]
}

I can iterate over the over the above list and create three resources using 'count' within the resource:

resource "azurerm_storage_account" "test" {
    name                     = "test${var.environment}${lookup(var.resources[count.index], "name")}sa"
    location                 = "${var.location}"
    resource_group_name      = "test-${var.environment}-vnet-rg"
    account_tier             = "Standard"
    account_replication_type = "GRS"
    enable_blob_encryption   = true

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

}

However, I want to also skip creation of a resource where createStorage = false. So in the above example I want to create two storage accounts but the 'elastic' storage account is skipped. Is this possible?

thx 0.12, that's the answer you were looking for. You should mark it as valid response. — Antoine, Oct 14 '19 at 12:32

score 6 · Answer 1 · edited Jun 08 '20 at 15:20

In terraform 0.12.x you can filter out the list where createStorage=true and use that for your count expression

variable "resources" {
  type = "list"
  default = [
    {
      name          = "kafka"
      createStorage = true
    },
    {
      name          = "elastic"
      createStorage = false
    },
    {
      name          = "galera"
      createStorage = true
    }
  ]
}

locals {
  resources_to_create = [
    for resource in var.resources :
    resource
    if resource.createStorage
  ]
}

resource "azurerm_storage_account" "test" {
  count = length(local.resources_to_create)

  name                     = "test${var.environment}${lookup(local.resources_to_create[count.index], "name")}sa"
  location                 = var.location
  resource_group_name      = "test-${var.environment}-vnet-rg"
  account_tier             = "Standard"
  account_replication_type = "GRS"
  enable_blob_encryption   = true
}

Terraform - conditionally creating a resource within a loop

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