diff --git a/modules/nebula/main.tf b/modules/nebula/main.tf
index 9882f61..ced9bc6 100644
--- a/modules/nebula/main.tf
+++ b/modules/nebula/main.tf
@@ -1,5 +1,25 @@
 variable "vms" {
-    type = map
+    type = map(string,object(
+      {
+        domain = string
+        cpu = number
+        vcpu = number
+        ram = number
+        system_image_persistent = bool
+        data_image_persistent = bool
+        data_disks = list(object({
+          name = string
+          size = string
+          persistent = bool
+        }))
+        network_interfaces = list(object({
+          network_id = string
+          ip = string
+          mac = string
+        }))
+        sysdatastore = string
+      }
+    ))
     description = "Virtual Machines description"
 }
 
@@ -40,7 +60,7 @@ resource "opennebula_image" "system" {
   name = "system-${each.key}.${each.value.domain}"
   description = "System disk for ${each.key}"
   datastore_id = var.one_prod_ds 
-  path = "https://vulcain.cadoles.com/empty_20G"
+  path = "https://vulcain.cadoles.com/empty_10G"
   persistent = each.value.system_image_persistent
   format = var.image_format
   dev_prefix = var.dev_prefix