add nat_gateway and add ref

main.tf

@@ -1,7 +1,14 @@
 terraform {
-  backend "local" {
-    path = "terraform.tfstate"
-  }
+  required_version = ">= 0.14.0"
+}
+
+variable "project_id" {
+  description = "The ID of the GCP project."
+}
+
+variable "region" {
+  description = "The region to create resources in."
+  default = "us-central1"
 }
 
 provider "google" {
@@ -10,22 +17,31 @@ provider "google" {
 }
 
 module "network" {
-  source     = "./modules/network"
-  project_id = var.project_id
-  region     = var.region
-  network    = var.network
-  subnet     = var.subnet
+  source = "./modules/network"
 }
 
 module "backend" {
   source = "./modules/backend"
+  startup_script = module.network.startup_script
+}
+
+module "nat_gateway" {
+  source = "./modules/network/nat_gateway"
+  network_name = module.network.network_name
+  region = var.region
+}
+
+module "firewall" {
+  source = "./modules/firewall"
+  network_name = module.network.network_name
 }
 
 module "frontend" {
-  source        = "./modules/frontend"
-  project_id    = var.project_id
-  region        = var.region
-  instance_type = var.instance_type
-  backend_ip    = module.network.backend_ip
-  subnet_ip     = module.network.subnet_ip
+  source = "./modules/frontend"
+  backend_service_name = module.backend.backend_service_name
+  network_name = module.network.network_name
+}
+
+output "frontend_external_ip" {
+  value = module.frontend.external_ip
 }