Added kubernetes version assertion (#21)

Author: ThinkBriK

checks.tf

@@ -0,0 +1,16 @@
+# This file contains assertions for variables based on the (horrible) workaround
+# https://www.linkedin.com/pulse/devops-how-do-assertion-test-terraform-template-jamie-nelson/
+locals {
+  # The minimal desired kubernetes version
+
+  kubernetes_minimal_major_version = 1
+  kubernetes_minimal_minor_version = 9
+  kubernetes_split_version         = "${split(".", var.kubernetes_version)}"
+  kubernetes_major_version_OK      = "${element(local.kubernetes_split_version, 0) >= local.kubernetes_minimal_major_version ? 0 : 1}"
+  kubernetes_minor_version_OK      = "${element(local.kubernetes_split_version, 1) >= local.kubernetes_minimal_minor_version ? 0 : 1}"
+}
+
+resource "null_resource" "test_version" {
+  count = "${ max(local.kubernetes_major_version_OK, local.kubernetes_minor_version_OK)}"
+  "ERROR: Kubernetes supported versions are over >= ${local.kubernetes_minimal_major_version}.${local.kubernetes_minimal_minor_version}" = true
+}