Changed the method of defining subnets in the main module.

main.tf

@@ -18,13 +18,7 @@ module "network" {
   source = "./modules/network"
 
   name = var.network_name
-  subnets = [
-    {
-      name   = var.subnet_name
-      region = var.region
-      cidr   = var.subnet_cidr
-    }
-  ]
+  subnets = var.subnets
 }
 
 module "vm" {
@@ -32,7 +26,7 @@ module "vm" {
 
   name         = "vm-test"
   network_name = var.network_name
-  subnet_name  = var.subnet_name
+  subnet_name  = var.subnets[0].name
   ssh          = var.ssh
 
   depends_on = [module.network]

variables.tf

@@ -6,13 +6,13 @@ variable "project_id" {
 variable "region" {
   description = "The region for the resources."
   type        = string
-  default     = "europe-central2"
+  default     = "us-west1"
 }
 
 variable "zone" {
   description = "The zone for the resources."
   type        = string
-  default     = "europe-central2-b"
+  default     = "us-west1-a"
 }
 
 variable "network_name" {
@@ -21,16 +21,25 @@ variable "network_name" {
   default     = "dom-lab-network"
 }
 
-variable "subnet_name" {
-  description = "The name of the subnet."
-  type        = string
-  default     = "waw-default"
-}
+variable "subnets" {
+  description = "A list of subnets to create."
 
-variable "subnet_cidr" {
-  description = "The CIDR range for the subnet."
-  type        = string
-  default     = "192.168.16.0/24"
+  type = list(object({
+    name   = string
+    cidr   = string
+    region = string
+  }))
+
+  default = [{
+    name   = "waw-default"
+    cidr   = "192.168.16.0/24"
+    region = "us-west1"
+  }]
+
+  validation {
+    condition     = var.subnets[0].region != null
+    error_message = "The region for the first subnet must be specified."
+  }
 }
 
 variable "ssh" {