add ability to change disk size

shared_modules/volume.tf

@@ -1,9 +1,25 @@
-resource "libvirt_volume" "vm_disk" {
-  count  = var.instance_count
-  name   = "${var.vm_name}-${count.index}"
+# Base volume (template/parent)
+resource "libvirt_volume" "base_vm_image" {
+  name   = "${var.vm_name}-base"
   pool   = "${var.vm_name}-pool"
   source = var.image_location
   format = "qcow2"
 
-  depends_on = [libvirt_pool.tf_tmp_storage]
-}
+  depends_on = [
+    libvirt_pool.tf_tmp_storage
+  ]
+}
+
+# Clone volume with resizable size
+resource "libvirt_volume" "vm_disk" {
+  count          = var.instance_count
+  name           = "${var.vm_name}-${count.index}"
+  pool           = "${var.vm_name}-pool"
+  format         = "qcow2"
+  size           = var.disk_size_bytes
+  base_volume_id = libvirt_volume.base_vm_image.id
+
+  depends_on = [
+    libvirt_volume.base_vm_image
+  ]
+}