Ensure string type in provnet-network-type ext_id

When multiple segments exist, or when deleting all segments, the
provider:network_type can be None which is not a valid value
for an ovsdb external_id column, which only stores strings.

Closes-Bug: #2098815
Change-Id: I7312570520bfc0e3d5e8e68cf065577cd3dc8786

neutron/common/utils.py

@@ -17,6 +17,7 @@
 # when needed.
 
 """Utilities and helper functions."""
+from collections import abc
 import datetime
 import functools
 import hashlib
@@ -1104,3 +1105,11 @@ def ts_to_datetime(timestamp):
 def datetime_to_ts(_datetime):
     """Converts datetime to timestamp in seconds"""
     return int(datetime.datetime.timestamp(_datetime))
+
+
+def stringmap(data: abc.Mapping[str, typing.Any],
+              default: str = '') -> dict[str, str]:
+    result = {}
+    for key, value in data.items():
+        result[key] = default if value is None else str(value)
+    return result

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py

@@ -2091,21 +2091,24 @@ class OVNClient:
         return (ovn_const.ETHTYPE_8021ad if network.get(qinq_apidef.QINQ_FIELD)
                 else ovn_const.ETHTYPE_8021q)
 
-    def _gen_network_parameters(self, network):
+    def _gen_network_parameters(self,
-        params = {'external_ids': {
+                                network: dict) -> dict[str, dict[str, str]]:
+        ext_ids = {
             ovn_const.OVN_NETWORK_NAME_EXT_ID_KEY: network['name'],
-            ovn_const.OVN_NETWORK_MTU_EXT_ID_KEY: str(network['mtu']),
+            ovn_const.OVN_NETWORK_MTU_EXT_ID_KEY: network['mtu'],
-            ovn_const.OVN_REV_NUM_EXT_ID_KEY: str(
+            ovn_const.OVN_REV_NUM_EXT_ID_KEY:
-                utils.get_revision_number(network, ovn_const.TYPE_NETWORKS)),
+                utils.get_revision_number(network, ovn_const.TYPE_NETWORKS),
             ovn_const.OVN_AZ_HINTS_EXT_ID_KEY:
                 ','.join(common_utils.get_az_hints(network)),
             # NOTE(ralonsoh): it is not considered the case of multiple
             # segments.
+            # NOTE(twilson): in the case of multiple segments, or when all
+            # segments are removed, NETWORK_TYPE=None, which is invalid ovsdb
             ovn_const.OVN_NETTYPE_EXT_ID_KEY: network.get(pnet.NETWORK_TYPE),
-        }}
+        }
 
         # Enable IGMP snooping if igmp_snooping_enable is enabled in Neutron
-        params['other_config'] = {
+        other_config = {
             ovn_const.MCAST_SNOOP:
                 ovs_conf.get_igmp_snooping_enabled(),
             ovn_const.MCAST_FLOOD_UNREGISTERED:
@@ -2113,15 +2116,15 @@ class OVNClient:
             ovn_const.VLAN_PASSTHRU: str(
                 self._get_vlan_passthru(network)).lower()}
         if utils.is_provider_network(network):
-            params['other_config'][ovn_const.LS_OPTIONS_FDB_AGE_THRESHOLD] = (
+            other_config[ovn_const.LS_OPTIONS_FDB_AGE_THRESHOLD] = (
                 ovn_conf.get_fdb_age_threshold())
         if utils.is_external_network(network):
-            params['other_config'][
+            other_config[ovn_const.LS_OPTIONS_BROADCAST_ARPS_ROUTERS] = (
-                ovn_const.LS_OPTIONS_BROADCAST_ARPS_ROUTERS] = (
                 'true'
                 if ovn_conf.is_broadcast_arps_to_all_routers_enabled() else
                 'false')
-        return params
+        return {'external_ids': common_utils.stringmap(ext_ids),
+                'other_config': common_utils.stringmap(other_config)}
 
     def create_network(self, context, network):
         # Create a logical switch with a name equal to the Neutron network

neutron/tests/unit/common/test_utils.py

@@ -665,3 +665,15 @@ class ParsePermittedEthertypesTestCase(base.BaseTestCase):
                            '0x123R'),
                  ]
         mock_log.warning.assert_has_calls(calls)
+
+
+class StringMapTestCase(base.BaseTestCase):
+    data = {'a': 1, 'b': None, 'c': 'hi'}
+
+    def test_stringmap(self):
+        expected = {'a': '1', 'b': '', 'c': 'hi'}
+
+        self.assertEqual(expected, utils.stringmap(self.data))
+
+    def test_stringmap_custom_default(self):
+        self.assertEqual('None', utils.stringmap(self.data, 'None')['b'])