fix: harden cluster rebuild determinism

terraform/variables.tf

@@ -20,6 +20,11 @@ variable "control_plane_count" {
   description = "Number of control plane nodes"
   type        = number
   default     = 3
+
+  validation {
+    condition     = var.control_plane_count > 0
+    error_message = "control_plane_count must be greater than zero."
+  }
 }
 
 variable "control_plane_cores" {
@@ -44,6 +49,11 @@ variable "worker_count" {
   description = "Number of worker nodes"
   type        = number
   default     = 5
+
+  validation {
+    condition     = var.worker_count >= 0
+    error_message = "worker_count must be zero or greater."
+  }
 }
 
 variable "worker_cores" {
@@ -193,24 +203,44 @@ variable "control_plane_ips" {
   description = "Static IPv4 addresses for control plane VMs"
   type        = list(string)
   default     = ["10.27.27.30", "10.27.27.31", "10.27.27.32"]
+
+  validation {
+    condition     = length(var.control_plane_ips) == length(distinct(var.control_plane_ips))
+    error_message = "control_plane_ips must be unique."
+  }
 }
 
 variable "worker_ips" {
   description = "Static IPv4 addresses for worker VMs"
   type        = list(string)
   default     = ["10.27.27.41", "10.27.27.42", "10.27.27.43", "10.27.27.44", "10.27.27.45"]
+
+  validation {
+    condition     = length(var.worker_ips) == length(distinct(var.worker_ips))
+    error_message = "worker_ips must be unique."
+  }
 }
 
 variable "control_plane_vm_ids" {
   description = "Fixed VMIDs for control plane VMs"
   type        = list(number)
   default     = [200, 201, 202]
+
+  validation {
+    condition     = length(var.control_plane_vm_ids) == length(distinct(var.control_plane_vm_ids))
+    error_message = "control_plane_vm_ids must be unique."
+  }
 }
 
 variable "worker_vm_ids" {
   description = "Fixed VMIDs for worker VMs"
   type        = list(number)
   default     = [210, 211, 212, 213, 214]
+
+  validation {
+    condition     = length(var.worker_vm_ids) == length(distinct(var.worker_vm_ids))
+    error_message = "worker_vm_ids must be unique."
+  }
 }
 
 variable "kube_api_vip" {