diff --git a/structure.yml b/structure.yml
index b9aaffe..dafb98e 100644
--- a/structure.yml
+++ b/structure.yml
@@ -2,10 +2,18 @@
 ---
 version: 1.1
 
-vps_domain_name:
-  description: The domain name of the VPS
-  examples:
-    - example.fr
+vps:
+  description: vps target server system variables
+
+  domain_name:
+    description: The domain name of the VPS
+    examples:
+      - example.fr
+
+  ssh_key:
+    description: vps ssh private key 
+    examples:
+      - ./sshkeys/myssh_privatekey
 
 nginx:
   description: pedagogic html static file server
@@ -36,7 +44,7 @@ nginx:
       - example.fr
     type: domainname
     default:
-      variable: __.vps_domain_name
+      variable: __.vps.domain_name
 
   email:
     description: email for the domain name
diff --git a/userdata.yml b/userdata.yml
index 9eeb1e3..6902a70 100644
--- a/userdata.yml
+++ b/userdata.yml
@@ -1,6 +1,8 @@
 ---
 
-vps_domain_name: tutu.fr
+vps:
+  domain_name: tutu.fr
+  ssh_key: ./host_vars/forge.gwhirlingai.fr.key
 
 nginx: