added hostname variable cause TF is whining

report_module_usage.tf

@@ -26,7 +26,7 @@ resource "null_resource" "wait_for_module" {
   count = 50
   depends_on = [ scalr_module.report_module ]
   provisioner "local-exec" {
-    command = "sed 's#url = \"your_url_here\"#url = \"https://$${SCALR_HOSTNAME}/api/iacp/v3/modules/${scalr_module.report_module[count.index].id}\"#; s#bearer_token = \"your_bearer_token_here\"#bearer_token = \"${var.token}\"#' wait_for_module.py > wait_for_module_${count.index}.py && pip install requests && python3 wait_for_module_${count.index}.py"
+    command = "sed 's#url = \"your_url_here\"#url = \"https://${var.scalr_url}/api/iacp/v3/modules/${scalr_module.report_module[count.index].id}\"#; s#bearer_token = \"your_bearer_token_here\"#bearer_token = \"${var.token}\"#' wait_for_module.py > wait_for_module_${count.index}.py && pip install requests && python3 wait_for_module_${count.index}.py"
   }
 }
 

variables.tf

@@ -16,6 +16,10 @@ variable "token" {
 #  sensitive = true
 }
 
+variable "scalr_url" {
+  description = "Scalr URL you create your resources in. WITHOUT the /v2/ part. Example: https://scalr-iacp.scalr.io"
+}
+
 variable "opa_version" {
   description = "OPA version used to create policy group. Should be one of available with current instance."
   default     = "0.32.0"