Terraform Breadth first search algorithm on GCP

main.tf

# Context: Given a GCP organisation node (the organisation itself or one of its subfolder) I need to get all the gcp project ids under this node, flattened in a single list.
# Terraform lacks of support to run trough graph structures like a tree. 
# The below code is a breadth first search run. Depth first search would require recursivity, smthg that I didn't find on HCL.
# Last but not least, once I managed to get a working code after one hour of several tries I found the terraform resource which encapsulate what I needed first. 
# https://registry.terraform.io/providers/hashicorp/google/latest/docs/data-sources/cloud_asset_resources_search_all#argument-reference

provider "google" {
  user_project_override = true
  billing_project       = <TO-REPLACE>
}

provider "google-beta" {
  user_project_override = true
  billing_project       = <TO-REPLACE>
}

locals {
  #parent_node = "organizations/<TO-REPLACE>"
  parent_node = "folders/<TO-REPLACE>"
}

data "google_folders" "folders_level_0" {
  parent_id = local.parent_node
}

data "google_folders" "folders_level_1" {
  for_each  = toset(data.google_folders.folders_level_0.folders.*.name)
  parent_id = each.value
}

data "google_folders" "folders_level_2" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_1).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_3" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_2).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_4" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_4).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_5" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_4).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_6" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_5).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_7" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_5).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_8" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_5).*.folders : v.*.name]))
  parent_id = each.value
}

data "google_folders" "folders_level_9" {
  for_each  = toset(flatten([for v in values(data.google_folders.folders_level_5).*.folders : v.*.name]))
  parent_id = each.value
}

locals {
  folder_names = flatten(
    [
      [local.parent_node],
      toset(data.google_folders.folders_level_0.folders.*.name),
      toset(flatten([for v in values(data.google_folders.folders_level_1).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_2).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_3).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_4).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_5).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_6).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_7).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_8).*.folders : v.*.name])),
      toset(flatten([for v in values(data.google_folders.folders_level_9).*.folders : v.*.name])),
    ]
  )
}

data "google_projects" "my-org-projects" {
  for_each = toset(local.folder_names)

  filter = "parent.id:${split("/", each.value)[1]}"
}


locals {
  projects_list = flatten(values(data.google_projects.my-org-projects).*.projects).*.project_id
}

output "projects_list" {
  value = length(local.projects_list)
}
        
# VS
        
data "google_cloud_asset_resources_search_all" "cloud_build_projects" {
  provider = google-beta
  scope    = local.parent_node
  # https://cloud.google.com/asset-inventory/docs/supported-asset-types
  asset_types = [
    "cloudresourcemanager.googleapis.com/Project"
  ]

}

locals {

  projects = [
    for v in
    [
      for v in data.google_cloud_asset_resources_search_all.cloud_build_projects.results : tostring(v.name)
    ]
    : split("projects/", v)[1]
  ]
}
    
output "projects_list_2" {
  value = length(local.projects)
}

# project_list1 and 2 are equal in the end