workspace_checker for 0.12, does NOT work with 0.11

dot_twelve_workspace_checker

locals {
  invalid_workspace = contains(var.valid_workspaces, terraform.workspace) ? null : file(
    "ERROR: You're running in the ${terraform.workspace} workspace which isn't valid for this project. You can set the workspace name by typing: terraform workspace select <name>. Valid workspaces for this project are: ${join(",", var.valid_workspaces)}",
  )
}

variable "valid_workspaces" {
  description = "List of valid workspaces for this project"
  type        = list(string)
}

resource "null_resource" "workspace_checker" {
}