auto start iface + add variables for gateway

static_iface.j2

+auto {{ifname}}
 iface {{ifname}} inet static
     address {{ip}}
     netmask {{netmask}}
@@ -7,12 +8,14 @@ iface {{ifname}} inet static
 {% endif %}
 
 {% if type == "router" %}
+auto {{ifname2}}
 iface {{ifname2}} inet static
     address {{ip2}}
     netmask {{netmask}}
     {% if inventory_hostname == "R1" %}
-    post-up ip route add 3.0.0.0/24 nexthop via 2.0.0.2
+    post-up ip route add 3.0.0.0/24 nexthop via {{gateway}}
     {% else %}
-    post-up ip route add 1.0.0.0/24 nexthop via 2.0.0.1
+    post-up ip route add 1.0.0.0/24 nexthop via {{gateway}}
     {% endif %}
 {% endif %}
+