sysconfig: support subnet type of 'manual'.

The subnet type 'manual' was used as a way to declare a device
and set an MTU for it but not assign network addresses.

This updates the manual example config to handle that case and
provides expected rendered output for sysconfig, eni, and netplan.

1 files changed, 7 insertions, 2 deletions

diff --git a/cloudinit/net/sysconfig.py b/cloudinit/net/sysconfig.py
index 9184bce6..a550f97c 100644
--- a/cloudinit/net/sysconfig.py
+++ b/cloudinit/net/sysconfig.py
@@ -61,6 +61,9 @@ class ConfigMap(object):
     def __getitem__(self, key):
         return self._conf[key]
 
+    def __contains__(self, key):
+        return key in self._conf
+
     def drop(self, key):
         self._conf.pop(key, None)
 
@@ -298,14 +301,16 @@ class Renderer(renderer.Renderer):
                 if subnet_is_ipv6(subnet):
                     mtu_key = 'IPV6_MTU'
                     iface_cfg['IPV6INIT'] = True
-
                 if 'mtu' in subnet:
                     iface_cfg[mtu_key] = subnet['mtu']
+            elif subnet_type == 'manual':
+                # If the subnet has an MTU setting, then ONBOOT=True
+                # to apply the setting
+                iface_cfg['ONBOOT'] = mtu_key in iface_cfg
             else:
                 raise ValueError("Unknown subnet type '%s' found"
                                  " for interface '%s'" % (subnet_type,
                                                           iface_cfg.name))
-
             if subnet.get('control') == 'manual':
                 iface_cfg['ONBOOT'] = False