schema constants: Update the constant list

Add new content and refactor a bit the constants.

Signed-off-by: Edward Haas <edwardh@redhat.com>

libnmstate/netapplier.py

@@ -30,6 +30,7 @@ from libnmstate.appliers import linux_bridge
 from libnmstate.nm import nmclient
 from libnmstate.prettystate import format_desired_current_state_diff
 from libnmstate.schema import Constants
+from libnmstate.schema import InterfaceType
 
 
 class ApplyError(Exception):
@@ -405,7 +406,7 @@ def _remove_down_virt_iface_entries(ifaces_desired_state):
     for ifname, ifstate in six.viewitems(ifaces_desired_state):
         is_virt_down = (
                 ifstate.get('state') == 'down' and
-                ifstate.get('type') in Constants.VIRT_IFACE_TYPES
+                ifstate.get('type') in InterfaceType.VIRT_TYPES
         )
         if not is_virt_down:
             ifaces[ifname] = ifstate

libnmstate/schema.py

@@ -28,8 +28,31 @@ def load(schema_name):
 ifaces_schema = load('operational-state')
 
 
+class Interface(object):
+    KEY = 'interfaces'
+
+    NAME = 'name'
+    TYPE = 'type'
+    STATE = 'state'
+
+    IPV4 = 'ipv4'
+    IPV6 = 'ipv6'
+
+
 class Constants(object):
-    INTERFACES = 'interfaces'
+    INTERFACES = Interface.KEY
+
+
+class InterfaceState(object):
+    KEY = Interface.STATE
+
+    DOWN = 'down'
+    UP = 'up'
+    ABSENT = 'absent'
+
+
+class InterfaceType(object):
+    KEY = Interface.TYPE
 
     BOND = 'bond'
     LINUX_BRIDGE = 'linux-bridge'
@@ -38,7 +61,7 @@ class Constants(object):
     OVS_INTERFACE = 'ovs-interface'
     VLAN = 'vlan'
 
-    VIRT_IFACE_TYPES = (
+    VIRT_TYPES = (
         BOND,
         LINUX_BRIDGE,
         OVS_BRIDGE,