Terraform - ordered generation of resources which are related based on a list variable - terraform

Question

I currently try to automate nested SumoLogic forder creation as part of my custom module. I have to use this resource. I need to create a folder path similar to:
parent_folder_path = "SRE/Test/Troubleshooting"
and due to the fact that this variable will change between environments I cannot hardcode creation of the underlying resources. The problematic part is that all shown folders (SRE, Test, Troubleshooting) need to be created in a sequence because the latter needs id of the former (eg. Test folder needs id of already created SRE folder) to be created.
The end result at which I am aiming is automatically generated code as below:
resource "sumologic_folder" "SRE" {
provider = sumologic
name = "SRE"
description = ""
parent_id = "0000000000XXXXX"
}
resource "sumologic_folder" "Test" {
provider = sumologic
name = "Test"
description = ""
parent_id = sumologic_folder.SRE.id
}
resource "sumologic_folder" "Troubleshooting" {
provider = sumologic
name = "Troubleshooting"
description = ""
parent_id = sumologic_folder.Test.id
}
I tried an approach which uses templatefile() and local_file:
parent_directories.tftpl
%{~ for index, path_part in parent_folder_path ~}
%{~ if index == 0 ~}
resource "sumologic_folder" "${replace(path_part, " ", "_")}" {
provider = sumologic
name = "${path_part}"
description = ""
parent_id = "${root_folder_id}"
}
%{~ else }
resource "sumologic_folder" "${replace(path_part, " ", "_")}" {
provider = sumologic
name = "${path_part}"
description = ""
parent_id = sumologic_folder.${replace(parent_folder_path[index - 1], " ", "_")}.id
}
%{~ endif ~}
%{~ endfor ~}
main.tf
resource "local_file" "parent_directories" {
content = templatefile("${path.module}/parent_directories.tftpl", { parent_folder_path = split("/", var.parent_folder_path), root_folder_id = var.root_folder_id })
filename = "${path.module}/parent_directories.tf"
}
and the file was correctly generated during terraform apply run but I was not able to include it in the scope of the run dynamically.
Does anyone know how to handle such usecase?
Thanks in advance for all help.
Best Regards,
Rafal.

Answer 1

I understand what you are trying to achieve - you want to create multiple resources of the same type, but relying on each one of them created before (previous one on the list), at the same time not knowing how many there would be (more folders in path). I am afraid it is not how Terraform works. You would create a cycle between the list or map of the same resources.
That said, however, I can offer you the ugly solution. If you can limit to some number of subdirectories, let's say up to five or ten levels, you can do that in the code that will create three folders if there are three dirs in the path, and four if there are four, and so on. You just stop creating resources if this level is empty.
Let's say you have a sumo module:
variable "parent_path" {}
variable "name" {}
data "sumologic_folder" "parent" {
path = var.parent_path
}
resource "sumologic_folder" "folder" {
provider = sumologic
name = var.name
description = ""
parent_id = data.sumologic_folder.parent.id
}
output "path" {
value = "${var.path}/${var.name}"
}
And then you can split the path to the list of folders and create as many resources as there are folders in the path, for example: AA/BB/CC/DD = 4 sumofolders.
locals {
desired_path = "SRE/Test/Troubleshooting" # example - 3 folders
regex = regexall("[^//]+", local.desired_path)
path0 = "/"
}
module "sumo" {
source = "./sumo"
name = local.regex[0]
parent_path = local.path0 # var.parent_path
}
module "sumo_child_1" {
source = "./sumo"
count = try(local.regex[1], null) == null ? 0 : 1
name = try(local.regex[1], "none")
parent_path = module.sumo.path
}
module "sumo_child_2" {
source = "./sumo"
count = try(local.regex[2], null) == null ? 0 : 1
name = try(local.regex[2], "none")
parent_path = module.sumo_child_1.path
}
module "sumo_child_3" { # this is NOT going to be even created in our example
source = "./sumo"
count = try(local.regex[3], null) == null ? 0 : 1
name = try(local.regex[3], "none")
parent_path = module.sumo_child_2.path
}
# and so on... if there are no more folders in the path, the resources won't be created anyway.
Now let me say that again, this is a very ugly solution... but it works. Cheers.