Merge pull request #24 from stackhpc/stackhpc/victoria-ngs-manage-vlans

Add ngs_manage_vlans configuration

doc/source/configuration.rst

@@ -244,3 +244,25 @@ For example::
 
 Some switches have issues assigning VLANs a name that starts with a number,
 and this configuration option can be used to avoid this.
+
+Manage VLANs
+============
+
+By default, on network creation VLANs are added to all switches. In a similar
+way, VLANs are removed when it seems they are no longer required.
+However, in some cases only a subset of the ports are managed by Neutron.
+In a similar way, when multiple switches are used, it is very common that
+the network administrator restricts the VLANs allowed. In these cases, there
+is little utility in adding and removing vlans on the switches. This process
+takes time, so not doing this can speed up a number of common operations.
+A particular case where this can cause problems is when a VLAN used for
+the switch management interface, or any other port not managed by Neutron,
+is removed by this Neutron driver.
+
+To stop networking generic switch trying to add or remove VLANs on the switch
+administrator are expected to pre-add all enabled VLANs. Once those VLANs are
+preconfigured on the switch, you can use the following configuration to stop
+networking generic switch adding or removing any VLANs::
+
+    [genericswitch:device-hostname]
+    ngs_manage_vlans = False

networking_generic_switch/devices/__init__.py

@@ -40,6 +40,8 @@
     # String format for network name to configure on switches.
     # Accepts {network_id} and {segmentation_id} formatting options.
     {'name': 'ngs_network_name_format', 'default': '{network_id}'},
+    # If false, ngs will not add and delete VLANs from switches
+    {'name': 'ngs_manage_vlans', 'default': True},
 ]
 
 
@@ -130,6 +132,10 @@ def _get_network_name(self, network_id, segmentation_id):
         return network_name_format.format(network_id=network_id,
                                           segmentation_id=segmentation_id)
 
+    def _do_vlan_management(self):
+        """Check if drivers should add and remove VLANs from switches."""
+        return strutils.bool_from_string(self.ngs_config['ngs_manage_vlans'])
+
     @abc.abstractmethod
     def add_network(self, segmentation_id, network_id):
         pass

networking_generic_switch/devices/netmiko_devices/__init__.py

@@ -200,6 +200,10 @@ def send_commands_to_device(self, cmd_set):
 
     @check_output('add network')
     def add_network(self, segmentation_id, network_id):
+        if not self._do_vlan_management():
+            LOG.info(f"Skipping add network for {segmentation_id}")
+            return ""
+
         # NOTE(zhenguo): Remove dashes from uuid as on most devices 32 chars
         # is the max length of vlan name.
         network_id = uuid.UUID(network_id).hex
@@ -218,6 +222,10 @@ def add_network(self, segmentation_id, network_id):
 
     @check_output('delete network')
     def del_network(self, segmentation_id, network_id):
+        if not self._do_vlan_management():
+            LOG.info(f"Skipping delete network for {segmentation_id}")
+            return ""
+
         # NOTE(zhenguo): Remove dashes from uuid as on most devices 32 chars
         # is the max length of vlan name.
         network_id = uuid.UUID(network_id).hex

networking_generic_switch/tests/unit/netmiko/test_netmiko_base.py

@@ -67,6 +67,17 @@ def test_add_network_with_trunk_ports(self, m_check, m_sctd):
         m_sctd.assert_called_with([])
         m_check.assert_called_once_with('fake output', 'add network')
 
+    @mock.patch('networking_generic_switch.devices.netmiko_devices.'
+                'NetmikoSwitch.send_commands_to_device',
+                return_value='fake output')
+    @mock.patch('networking_generic_switch.devices.netmiko_devices.'
+                'NetmikoSwitch.check_output')
+    def test_add_network_with_no_manage_vlans(self, m_check, m_sctd):
+        switch = self._make_switch_device({'ngs_manage_vlans': False})
+        switch.add_network(22, '0ae071f5-5be9-43e4-80ea-e41fefe85b21')
+        self.assertFalse(m_sctd.called)
+        m_check.assert_called_once_with('', 'add network')
+
     @mock.patch('networking_generic_switch.devices.netmiko_devices.'
                 'NetmikoSwitch.send_commands_to_device',
                 return_value='fake output')
@@ -88,6 +99,17 @@ def test_del_network_with_trunk_ports(self, m_check, m_sctd):
         m_sctd.assert_called_with([])
         m_check.assert_called_once_with('fake output', 'delete network')
 
+    @mock.patch('networking_generic_switch.devices.netmiko_devices.'
+                'NetmikoSwitch.send_commands_to_device',
+                return_value='fake output')
+    @mock.patch('networking_generic_switch.devices.netmiko_devices.'
+                'NetmikoSwitch.check_output')
+    def test_del_network_with_no_manage_vlans(self, m_check, m_sctd):
+        switch = self._make_switch_device({'ngs_manage_vlans': False})
+        switch.del_network(22, '0ae071f5-5be9-43e4-80ea-e41fefe85b21')
+        self.assertFalse(m_sctd.called)
+        m_check.assert_called_once_with('', 'delete network')
+
     @mock.patch('networking_generic_switch.devices.netmiko_devices.'
                 'NetmikoSwitch.send_commands_to_device',
                 return_value='fake output')

releasenotes/notes/manage-vlans-c75e4c2e9b9b3403.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    New per switch `ngs_manage_vlans` option. It defaults to True, but can
+    be set to False so that no VLANs are added or removed on that switch.
+    This is useful when not all ports on the switch are managed by Neutron.