Define a validation rule for provision configuration

Author: cmd-ntrf

common/provision/main.tf

@@ -1,4 +1,9 @@
-variable "configuration" {}
+variable "configuration" {
+  validation {
+    condition = length(var.configuration.bastions) > 0
+    error_message = "Defined firewall rules do not allow Terraform to connect to the cluster through at least one instance."
+  }
+}
 variable "hieradata" {}
 variable "hieradata_dir" {}
 variable "eyaml_key" {}