[network_interfaces] Allow having auto-configurated interfaces

Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

group_vars/all/network_interfaces.yml

@@ -30,3 +30,5 @@ glob_network_interfaces:
       gateway: "{{ query('ldap', 'ip', 'dsi', 'renater') | ipv4 | first }}"
     - name: lp
       id: 56
+    - name: auto
+      id: 0

host_vars/routeur-ft.adm.crans.org.yml

@@ -0,0 +1,4 @@
+---
+interfaces:
+  adm: ens18
+  auto: ens19

host_vars/routeur-thot.adm.crans.org.yml

@@ -0,0 +1,4 @@
+---
+interfaces:
+  adm: ens18
+  auto: ens19

roles/network-interfaces/templates/network/interfaces.d/ifalias.j2

@@ -1,6 +1,11 @@
 {{ ansible_header | comment }}
 
 {% set vlan_name = (item.name | replace('_', '-')) %}
+{% if vlan_name == "auto" %}
+auto {{ interfaces[item.name] }}
+iface {{ interfaces[item.name] }} inet dhcp
+iface {{ interfaces[item.name] }} inet6 auto
+{% else %}
 {% set subnet_network = (query('ldap', 'network', vlan_name) | ipaddr('network')) %}
 {% set subnet_netmask = (query('ldap', 'network', vlan_name) | ipaddr('netmask')) %}
 {% set ips = query('ldap', 'ip', ansible_hostname, vlan_name) %}
@@ -63,3 +68,4 @@ iface {{ interfaces[item.name] }} inet6 static
 {% endfor %}
 {% endif %}
 {% endif %}
+{% endif %}