diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
deleted file mode 100644
index ad6b11a..0000000
--- a/.gitlab-ci.yml
+++ /dev/null
@@ -1,8 +0,0 @@
----
-stages:
-  - archive
-  
-include:
-  - project: Lab/stuttgart-things/stuttgart-things
-    file: build/gitlab/tasks/archive-module-pipeline.yaml
-    ref: master
diff --git a/provider.tf b/provider.tf
index 8d3d5ad..783c650 100644
--- a/provider.tf
+++ b/provider.tf
@@ -1,7 +1,10 @@
 terraform {
+  required_version = ">= 1.5.5"
+
   required_providers {
     proxmox = {
-      source = "Telmate/proxmox"
+      source  = "Telmate/proxmox"
+      version = ">= 2.9.14"
     }
   }
 }
diff --git a/variables.tf b/variables.tf
index 56ca19a..a25c4eb 100644
--- a/variables.tf
+++ b/variables.tf
@@ -1,124 +1,166 @@
 variable "pve_cluster_node" {
   default     = false
+  type        = string
   description = "name of proxmox cluster node"
 }
 
 variable "pve_folder_path" {
   default     = false
+  type        = string
   description = "target (vm) folder path of proxmox virtual machine"
 }
 
 variable "pve_datastore" {
   default     = false
+  type        = string
   description = "name of proxmox datastore"
 }
 
 variable "pve_network" {
   default     = false
+  type        = string
   description = "name of proxmox network"
 }
 
 variable "vm_numa" {
   default     = true
+  type        = bool
   description = "enable numa for vm"
 }
 
 variable "vm_onboot" {
   default     = true
+  type        = bool
   description = "whether to have the VM startup after the PVE node starts"
 }
 
 variable "vm_firmware" {
   default     = "seabios"
+  type        = string
   description = "the firmware interface to use on the virtual machine. Can be one of bios or EFI. Default: bios"
 }
 
 variable "vm_os_type" {
   default     = "l26"
+  type        = string
   description = "the type of OS in the guest to allow Proxmox to enable optimizations for the appropriate guest OS"
 }
 
 variable "vm_count" {
   default     = 1
+  type        = number
   description = "count of vms"
+
+  validation {
+    condition     = var.vm_count >= 1 && var.vm_count <= 5 && floor(var.vm_count) == var.vm_count
+    error_message = "Accepted values: 1-5."
+  }
+
 }
 
 variable "vm_name" {
-  default     = "terraform-vm"
+  default     = false
+  type        = string
   description = "name of proxmox virtual machine"
 }
 
 variable "vm_guest_agent" {
   default     = 1
+  type        = number
   description = "QEMU Guest Agent configuration set 0 to disable 1 to enable"
 }
 
 variable "vm_notes" {
   default     = false
+  type        = string
   description = "notes of proxmox virtual machine shwon in UI"
 }
 
 variable "vm_template" {
   default     = false
+  type        = string
   description = "name of proxmox virtual machine template"
 }
 
 variable "vm_num_cpus" {
   default     = 2
+  type        = number
   description = "amount of cpus of the vm"
+
+  validation {
+    condition     = contains([2, 4, 6, 8, 10, 12, 16], var.vm_num_cpus)
+    error_message = "Valid values for vm_num_cpus are (2, 4, 6, 8, 10, 12, 16)"
+  }
+
 }
 
 variable "vm_num_sockets" {
   default     = 1
+  type        = number
   description = "amount of sockets of the vm"
 }
 
 variable "vm_memory" {
-  default     = 2048
+  default     = 4096
+  type        = number
   description = "amount of memory of the vm"
 }
 
 variable "vm_disk_size" {
-  default     = "30G"
+  default     = "32G"
   description = "size of disk"
+
+  validation {
+    condition     = contains(["20G", "32G", "64G", "96G", "128G", "196G", "256G"], var.vm_disk_size)
+    error_message = "Valid values for vm_disk_size are (20G, 32G, 64G, 96G, 128G, 196G, 256G)"
+  }
+
 }
 
 variable "vm_disk_type" {
   default     = "virtio"
+  type        = string
   description = "type of disk"
 }
 
 variable "vm_bootdisk" {
   default     = "virtio0"
+  type        = string
   description = "default boot disk"
 }
 
 variable "vm_storage_controller" {
   default     = "virtio-scsi-pci"
+  type        = string
   description = "storage controller to emulate"
 }
 
 variable "vm_network_type" {
   default     = "virtio"
+  type        = string
   description = "network card type"
 }
 
 variable "vm_ssh_user" {
   default     = ""
+  type        = string
   description = "Username of VM"
 }
 
 variable "vm_ssh_password" {
   default     = ""
+  type        = string
   description = "Password of VM user"
 }
 
 variable "vm_network_address0" {
   default     = "ip=dhcp"
+  type        = string
   description = "The first IP address to assign to the guest (set to ip=dhcp to get a ip output)"
 }
 
 variable "vm_macaddr" {
   default     = null
+  type        = string
   description = "Mac address of desired vm"
 }
diff --git a/vm.tf b/vm.tf
index 85684d6..65126cf 100644
--- a/vm.tf
+++ b/vm.tf
@@ -16,25 +16,25 @@ resource "proxmox_vm_qemu" "proxmox_vm" {
   bootdisk    = var.vm_bootdisk
   agent       = var.vm_guest_agent
   qemu_os     = var.vm_os_type
-  
+
   disk {
     size    = var.vm_disk_size
     type    = var.vm_disk_type
     storage = var.pve_datastore
   }
-  
+
   network {
     model   = var.vm_network_type
     bridge  = var.pve_network
     macaddr = var.vm_macaddr
   }
-  
+
   lifecycle {
     ignore_changes = [
       network,
     ]
   }
-  
+
   connection {
     type     = "ssh"
     host     = self.default_ipv4_address