Trying to use another variable in validation block

Terraform
1

I am trying to use a variable validation in terraform, i am trying to deny role editor and owner while creating new project, however want to keep excpetions for some project. below is my terraform code.
i am getting errors in the validation block for using another variable
can some one help me with this ?

variable "iam_role_member" {
  type = map(list(string))

  validation {
    condition = length(setintersection(toset(keys(var.iam_role_member)),toset["roles/owner","roles/editor"]))) == 0 || length(var.allowed_project_ids) > 0
    error_message = "Project cannot have owner or editor roles."
  }
}

variable "allowed_project_ids" {
  type    = list(string)
  default = []
}

data "github_repository_file" "exception_project_list_id" {
  repository = "organization/exception-project-list-id"
  file_path  = "project-ids.txt"
}

locals {
  exception_project_ids = length(var.allowed_project_ids) > 0 ? data.github_repository_file.exception_project_list_id.content : []
  project_ids           = length(local.exception_project_ids) > 0 ? concat(local.exception_project_ids, var.allowed_project_ids) : var.allowed_project_ids
}

variable "project_ids" {
  type    = list(string)
  default = local.project_ids
}
2

Variable validation rules must be self-contained – referring only to their own values – because Terraform also checks them in limited evaluation contexts like the terraform validate command, which don’t always have a full evaluation context for the entire module.

This problem might be better solved using a precondition on one of your resources – probably whichever resource is declaring the roles in the remote system – since preconditions are evaluated during the plan and apply phases and so they can make use of any value available within the same module as the condition expression.

4

okay, thanks, we try to use precondition block to look for solution