kube-766: move service account id to vars

Author: ValyaB

examples/gke/gke_impersonate/castai.tf

@@ -1,7 +1,9 @@
+# Configure Data sources and providers required for CAST AI connection.
 locals {
-  service_account_id = "castai-gke-tf-${substr(sha1(var.cluster_name), 0, 8)}"
+  service_account_id = var.service_account_id != "" ? var.service_account_id : "castai-gke-tf-${substr(sha1(var.cluster_name), 0, 8)}"
 }
 
+# Configure GKE cluster connection.
 module "iam-impersonate" {
   source             = "castai/iam-impersonate/gke"
   version            = "1.0.0"
@@ -153,5 +155,8 @@ module "castai-gke-cluster" {
       }
     }
   }
+
+  // depends_on helps terraform with creating proper dependencies graph in case of resource creation and in this case destroy
+  // module "castai-gke-cluster" has to be destroyed before module "castai-gke-iam" and "module.gke"
   depends_on = [module.gke]
 }

examples/gke/gke_impersonate/variables.tf

@@ -48,3 +48,9 @@ variable "tags" {
   description = "Optional tags for new cluster nodes. This parameter applies only to new nodes - tags for old nodes are not reconciled."
   default     = {}
 }
+
+variable "service_account_id" {
+  type        = string
+  description = "Cast service account id for impersonation."
+  default = ""
+}