text: # Copyright (c) 2013 OpenStack Foundation
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  # implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import itertools
  import threading
  
  import jsonrpclib
  from oslo.config import cfg
  
  from neutron.common import constants as n_const
  from neutron.openstack.common import log as logging
  from neutron.plugins.ml2.common import exceptions as ml2_exc
  from neutron.plugins.ml2 import driver_api
  from neutron.plugins.ml2.drivers.arista import config  # noqa
  from neutron.plugins.ml2.drivers.arista import db
  from neutron.plugins.ml2.drivers.arista import exceptions as arista_exc
  
  LOG = logging.getLogger(__name__)
  
  EOS_UNREACHABLE_MSG = _('Unable to reach EOS')
  DEFAULT_VLAN = 1
  
  
  class AristaRPCWrapper(object):
      """Wraps Arista JSON RPC.
  
      All communications between Neutron and EOS are over JSON RPC.
      EOS - operating system used on Arista hardware
      Command API - JSON RPC API provided by Arista EOS
      """
      def __init__(self):
          self._server = jsonrpclib.Server(self._eapi_host_url())
          self.keystone_conf = cfg.CONF.keystone_authtoken
          self.region = cfg.CONF.ml2_arista.region_name
          self._region_updated_time = None
          # The cli_commands dict stores the mapping between the CLI command key
          # and the actual CLI command.
          self.cli_commands = {}
          self.initialize_cli_commands()
  
      def _get_exit_mode_cmds(self, modes):
          """Returns a list of 'exit' commands for the modes.
  
          :param modes: a list of CLI modes to exit out of.
          """
          return ['exit'] * len(modes)
  
      def initialize_cli_commands(self):
          self.cli_commands['timestamp'] = []
  
      def check_cli_commands(self):
          """Checks whether the CLI commands are vaild.
  
             This method tries to execute the commands on EOS and if it succeedes
             the command is stored.
          """
          cmd = ['show openstack config region %s timestamp' % self.region]
          try:
              self._run_eos_cmds(cmd)
              self.cli_commands['timestamp'] = cmd
          except arista_exc.AristaRpcError:
              self.cli_commands['timestamp'] = []
              msg = _("'timestamp' command '%s' is not available on EOS") % cmd
              LOG.warn(msg)
  
      def _keystone_url(self):
          keystone_auth_url = ('%s://%s:%s/v2.0/' %
                               (self.keystone_conf.auth_protocol,
                                self.keystone_conf.auth_host,
                                self.keystone_conf.auth_port))
          return keystone_auth_url
  
      def get_tenants(self):
          """Returns dict of all tenants known by EOS.
  
          :returns: dictionary containing the networks per tenant
                    and VMs allocated per tenant
          """
          cmds = ['show openstack config region %s' % self.region]
          command_output = self._run_eos_cmds(cmds)
          tenants = command_output[0]['tenants']
  
          return tenants
  
      def plug_port_into_network(self, vm_id, host_id, port_id,
                                 net_id, tenant_id, port_name, device_owner):
          """Genric routine plug a port of a VM instace into network.
  
          :param vm_id: globally unique identifier for VM instance
          :param host: ID of the host where the VM is placed
          :param port_id: globally unique port ID that connects VM to network
          :param network_id: globally unique neutron network identifier
          :param tenant_id: globally unique neutron tenant identifier
          :param port_name: Name of the port - for display purposes
          :param device_owner: Device owner - e.g. compute or network:dhcp
          """
          if device_owner == n_const.DEVICE_OWNER_DHCP:
              self.plug_dhcp_port_into_network(vm_id,
                                               host_id,
                                               port_id,
                                               net_id,
                                               tenant_id,
                                               port_name)
          elif device_owner.startswith('compute'):
              self.plug_host_into_network(vm_id,
                                          host_id,
                                          port_id,
                                          net_id,
                                          tenant_id,
                                          port_name)
  
      def plug_host_into_network(self, vm_id, host, port_id,
                                 network_id, tenant_id, port_name):
          """Creates VLAN between TOR and compute host.
  
          :param vm_id: globally unique identifier for VM instance
          :param host: ID of the host where the VM is placed
          :param port_id: globally unique port ID that connects VM to network
          :param network_id: globally unique neutron network identifier
          :param tenant_id: globally unique neutron tenant identifier
          :param port_name: Name of the port - for display purposes
          """
          cmds = ['tenant %s' % tenant_id,
                  'vm id %s hostid %s' % (vm_id, host)]
          if port_name:
              cmds.append('port id %s name "%s" network-id %s' %
                          (port_id, port_name, network_id))
          else:
              cmds.append('port id %s network-id %s' %
                          (port_id, network_id))
          cmds.append('exit')
          cmds.append('exit')
          self._run_openstack_cmds(cmds)
  
      def plug_dhcp_port_into_network(self, dhcp_id, host, port_id,
                                      network_id, tenant_id, port_name):
          """Creates VLAN between TOR and dhcp host.
  
          :param dhcp_id: globally unique identifier for dhcp
          :param host: ID of the host where the dhcp is hosted
          :param port_id: globally unique port ID that connects dhcp to network
          :param network_id: globally unique neutron network identifier
          :param tenant_id: globally unique neutron tenant identifier
          :param port_name: Name of the port - for display purposes
          """
          cmds = ['tenant %s' % tenant_id,
                  'network id %s' % network_id]
          if port_name:
              cmds.append('dhcp id %s hostid %s port-id %s name "%s"' %
                          (dhcp_id, host, port_id, port_name))
          else:
              cmds.append('dhcp id %s hostid %s port-id %s' %
                          (dhcp_id, host, port_id))
          cmds.append('exit')
          self._run_openstack_cmds(cmds)
  
      def unplug_host_from_network(self, vm_id, host, port_id,
                                   network_id, tenant_id):
          """Removes previously configured VLAN between TOR and a host.
  
          :param vm_id: globally unique identifier for VM instance
          :param host: ID of the host where the VM is placed
          :param port_id: globally unique port ID that connects VM to network
          :param network_id: globally unique neutron network identifier
          :param tenant_id: globally unique neutron tenant identifier
          """
          cmds = ['tenant %s' % tenant_id,
                  'vm id %s hostid %s' % (vm_id, host),
                  'no port id %s' % port_id,
                  'exit',
                  'exit']
          self._run_openstack_cmds(cmds)
  
      def unplug_dhcp_port_from_network(self, dhcp_id, host, port_id,
                                        network_id, tenant_id):
          """Removes previously configured VLAN between TOR and a dhcp host.
  
          :param dhcp_id: globally unique identifier for dhcp
          :param host: ID of the host where the dhcp is hosted
          :param port_id: globally unique port ID that connects dhcp to network
          :param network_id: globally unique neutron network identifier
          :param tenant_id: globally unique neutron tenant identifier
          """
          cmds = ['tenant %s' % tenant_id,
                  'network id %s' % network_id,
                  'no dhcp id %s port-id %s' % (dhcp_id, port_id),
                  'exit']
          self._run_openstack_cmds(cmds)
  
      def create_network(self, tenant_id, network):
          """Creates a single network on Arista hardware
  
          :param tenant_id: globally unique neutron tenant identifier
          :param network: dict containing network_id, network_name and
                          segmentation_id
          """
          self.create_network_bulk(tenant_id, [network])
  
      def create_network_bulk(self, tenant_id, network_list):
          """Creates a network on Arista Hardware
  
          :param tenant_id: globally unique neutron tenant identifier
          :param network_list: list of dicts containing network_id, network_name
                               and segmentation_id
          """
          cmds = ['tenant %s' % tenant_id]
          # Create a reference to function to avoid name lookups in the loop
          append_cmd = cmds.append
          for network in network_list:
              try:
                  append_cmd('network id %s name "%s"' %
                             (network['network_id'], network['network_name']))
              except KeyError:
                  append_cmd('network id %s' % network['network_id'])
              # Enter segment mode without exiting out of network mode
              if not network['segmentation_id']:
                  network['segmentation_id'] = DEFAULT_VLAN
              append_cmd('segment 1 type vlan id %d' %
                         network['segmentation_id'])
          cmds.extend(self._get_exit_mode_cmds(['segment', 'network', 'tenant']))
          self._run_openstack_cmds(cmds)
  
      def create_network_segments(self, tenant_id, network_id,
                                  network_name, segments):
          """Creates a network on Arista Hardware
  
          Note: This method is not used at the moment. create_network()
          is used instead. This will be used once the support for
          multiple segments is added in Neutron.
  
          :param tenant_id: globally unique neutron tenant identifier
          :param network_id: globally unique neutron network identifier
          :param network_name: Network name - for display purposes
          :param segments: List of segments in a given network
          """
          if segments:
              cmds = ['tenant %s' % tenant_id,
                      'network id %s name "%s"' % (network_id, network_name)]
              seg_num = 1
              for seg in segments:
                  cmds.append('segment %d type %s id %d' % (seg_num,
                              seg['network_type'], seg['segmentation_id']))
                  seg_num += 1
              cmds.append('exit')  # exit for segment mode
              cmds.append('exit')  # exit for network mode
              cmds.append('exit')  # exit for tenant mode
  
              self._run_openstack_cmds(cmds)
  
      def delete_network(self, tenant_id, network_id):
          """Deletes a specified network for a given tenant
  
          :param tenant_id: globally unique neutron tenant identifier
          :param network_id: globally unique neutron network identifier
          """
          self.delete_network_bulk(tenant_id, [network_id])
  
      def delete_network_bulk(self, tenant_id, network_id_list):
          """Deletes the network ids specified for a tenant
  
          :param tenant_id: globally unique neutron tenant identifier
          :param network_id_list: list of globally unique neutron network
                                  identifiers
          """
          cmds = ['tenant %s' % tenant_id]
          for network_id in network_id_list:
              cmds.append('no network id %s' % network_id)
          cmds.extend(self._get_exit_mode_cmds(['network', 'tenant']))
          self._run_openstack_cmds(cmds)
  
      def delete_vm(self, tenant_id, vm_id):
          """Deletes a VM from EOS for a given tenant
  
          :param tenant_id : globally unique neutron tenant identifier
          :param vm_id : id of a VM that needs to be deleted.
          """
          self.delete_vm_bulk(tenant_id, [vm_id])
  
      def delete_vm_bulk(self, tenant_id, vm_id_list):
          """Deletes VMs from EOS for a given tenant
  
          :param tenant_id : globally unique neutron tenant identifier
          :param vm_id_list : ids of VMs that needs to be deleted.
          """
          cmds = ['tenant %s' % tenant_id]
          for vm_id in vm_id_list:
              cmds.append('no vm id %s' % vm_id)
          cmds.extend(self._get_exit_mode_cmds(['vm', 'tenant']))
          self._run_openstack_cmds(cmds)
  
      def create_vm_port_bulk(self, tenant_id, vm_port_list, vms):
          """Sends a bulk request to create ports.
  
          :param tenant_id: globaly unique neutron tenant identifier
          :param vm_port_list: list of ports that need to be created.
          :param vms: list of vms to which the ports will be attached to.
          """
          cmds = ['tenant %s' % tenant_id]
          # Create a reference to function to avoid name lookups in the loop
          append_cmd = cmds.append
          for port in vm_port_list:
              try:
                  vm = vms[port['device_id']]
              except KeyError:
                  msg = _("VM id %(vmid)s not found for port %(portid)s") % {
                      'vmid': port['device_id'],
                      'portid': port['id']}
                  LOG.warn(msg)
                  continue
  
              port_name = '' if 'name' not in port else 'name "%s"' % (
                  port['name']
              )
  
              if port['device_owner'] == n_const.DEVICE_OWNER_DHCP:
                  append_cmd('network id %s' % port['network_id'])
                  append_cmd('dhcp id %s hostid %s port-id %s %s' %
                             (vm['vmId'], vm['host'], port['id'], port_name))
              elif port['device_owner'].startswith('compute'):
                  append_cmd('vm id %s hostid %s' % (vm['vmId'], vm['host']))
                  append_cmd('port id %s %s network-id %s' %
                             (port['id'], port_name, port['network_id']))
              else:
                  msg = _("Unknown device owner: %s") % port['device_owner']
                  LOG.warn(msg)
                  continue
  
          append_cmd('exit')
          self._run_openstack_cmds(cmds)
  
      def delete_tenant(self, tenant_id):
          """Deletes a given tenant and all its networks and VMs from EOS.
  
          :param tenant_id: globally unique neutron tenant identifier
          """
          self.delete_tenant_bulk([tenant_id])
  
      def delete_tenant_bulk(self, tenant_list):
          """Sends a bulk request to delete the tenants.
  
          :param tenant_list: list of globaly unique neutron tenant ids which
                              need to be deleted.
          """
  
          cmds = []
          for tenant in tenant_list:
              cmds.append('no tenant %s' % tenant)
          cmds.append('exit')
          self._run_openstack_cmds(cmds)
  
      def delete_this_region(self):
          """Deleted the region data from EOS."""
          cmds = ['enable',
                  'configure',
                  'cvx',
                  'service openstack',
                  'no region %s' % self.region,
                  'exit',
                  'exit',
                  'exit']
          self._run_eos_cmds(cmds)
  
      def register_with_eos(self):
          """This is the registration request with EOS.
  
          This the initial handshake between Neutron and EOS.
          critical end-point information is registered with EOS.
          """
  
          cmds = ['auth url %s user %s password %s tenant %s' % (
                  self._keystone_url(),
                  self.keystone_conf.admin_user,
                  self.keystone_conf.admin_password,
                  self.keystone_conf.admin_tenant_name)]
  
          log_cmds = ['auth url %s user %s password %s tenant %s' % (
                      self._keystone_url(),
                      self.keystone_conf.admin_user,
                      '******',
                      self.keystone_conf.admin_tenant_name)]
          self._run_openstack_cmds(cmds, commands_to_log=log_cmds)
  
      def clear_region_updated_time(self):
          """Clear the region updated time which forces a resync."""
  
          self._region_updated_time = None
  
      def region_in_sync(self):
          """Check whether EOS is in sync with Neutron."""
  
          eos_region_updated_times = self.get_region_updated_time()
          return (self._region_updated_time and
                 (self._region_updated_time['regionTimestamp'] ==
                  eos_region_updated_times['regionTimestamp']))
  
      def get_region_updated_time(self):
          """Return the timestamp of the last update.
  
             This method returns the time at which any entities in the region
             were updated.
          """
          timestamp_cmd = self.cli_commands['timestamp']
          if timestamp_cmd:
              return self._run_eos_cmds(commands=timestamp_cmd)[0]
          return None
  
      def _run_eos_cmds(self, commands, commands_to_log=None):
          """Execute/sends a CAPI (Command API) command to EOS.
  
          In this method, list of commands is appended with prefix and
          postfix commands - to make is understandble by EOS.
  
          :param commands : List of command to be executed on EOS.
          :param commands_to_log : This should be set to the command that is
                                   logged. If it is None, then the commands
                                   param is logged.
          """
  
          log_cmds = commands
          if commands_to_log:
              log_cmds = commands_to_log
  
          LOG.info(_('Executing command on Arista EOS: %s'), log_cmds)
  
          try:
              # this returns array of return values for every command in
              # full_command list
              ret = self._server.runCmds(version=1, cmds=commands)
          except Exception as error:
              host = cfg.CONF.ml2_arista.eapi_host
              error_msg_str = unicode(error)
              if commands_to_log:
                  # The command might contain sensitive information. If the
                  # command to log is different from the actual command, use
                  # that in the error message.
                  for cmd, log_cmd in itertools.izip(commands, log_cmds):
                      error_msg_str = error_msg_str.replace(cmd, log_cmd)
              msg = (_('Error %(err)s while trying to execute '
                       'commands %(cmd)s on EOS %(host)s') %
                    {'err': error_msg_str,
                     'cmd': commands_to_log,
                     'host': host})
              # Logging exception here can reveal passwords as the exception
              # contains the CLI command which contains the credentials.
              LOG.error(msg)
              raise arista_exc.AristaRpcError(msg=msg)
  
          return ret
  
      def _build_command(self, cmds):
          """Build full EOS's openstack CLI command.
  
          Helper method to add commands to enter and exit from openstack
          CLI modes.
  
          :param cmds: The openstack CLI commands that need to be executed
                       in the openstack config mode.
          """
  
          full_command = [
              'enable',
              'configure',
              'cvx',
              'service openstack',
              'region %s' % self.region,
          ]
          full_command.extend(cmds)
          full_command.extend(self._get_exit_mode_cmds(['region',
                                                        'openstack',
                                                        'cvx']))
          full_command.extend(self.cli_commands['timestamp'])
          return full_command
  
      def _run_openstack_cmds(self, commands, commands_to_log=None):
          """Execute/sends a CAPI (Command API) command to EOS.
  
          In this method, list of commands is appended with prefix and
          postfix commands - to make is understandble by EOS.
  
          :param commands : List of command to be executed on EOS.
          :param commands_to_logs : This should be set to the command that is
                                    logged. If it is None, then the commands
                                    param is logged.
          """
  
          full_command = self._build_command(commands)
          if commands_to_log:
              full_log_command = self._build_command(commands_to_log)
          else:
              full_log_command = None
          ret = self._run_eos_cmds(full_command, full_log_command)
          # Remove return values for 'configure terminal',
          # 'service openstack' and 'exit' commands
          if self.cli_commands['timestamp']:
              self._region_updated_time = ret[-1]
  
      def _eapi_host_url(self):
          self._validate_config()
  
          user = cfg.CONF.ml2_arista.eapi_username
          pwd = cfg.CONF.ml2_arista.eapi_password
          host = cfg.CONF.ml2_arista.eapi_host
  
          eapi_server_url = ('https://%s:%s@%s/command-api' %
                             (user, pwd, host))
          return eapi_server_url
  
      def _validate_config(self):
          if cfg.CONF.ml2_arista.get('eapi_host') == '':
              msg = _('Required option eapi_host is not set')
              LOG.error(msg)
              raise arista_exc.AristaConfigError(msg=msg)
          if cfg.CONF.ml2_arista.get('eapi_username') == '':
              msg = _('Required option eapi_username is not set')
              LOG.error(msg)
              raise arista_exc.AristaConfigError(msg=msg)
  
  
  class SyncService(object):
      """Synchronizatin of information between Neutron and EOS
  
      Periodically (through configuration option), this service
      ensures that Networks and VMs configured on EOS/Arista HW
      are always in sync with Neutron DB.
      """
      def __init__(self, rpc_wrapper, neutron_db):
          self._rpc = rpc_wrapper
          self._ndb = neutron_db
          self._force_sync = True
  
      def synchronize(self):
          """Sends data to EOS which differs from neutron DB."""
  
          LOG.info(_('Syncing Neutron <-> EOS'))
          try:
              # Get the time at which entities in the region were updated.
              # If the times match, then ML2 is in sync with EOS. Otherwise
              # perform a complete sync.
              if not self._force_sync and self._rpc.region_in_sync():
                  LOG.info(_('OpenStack and EOS are in sync!'))
                  return
          except arista_exc.AristaRpcError:
              LOG.warning(EOS_UNREACHABLE_MSG)
              self._force_sync = True
              return
  
          try:
              #Always register with EOS to ensure that it has correct credentials
              self._rpc.register_with_eos()
              eos_tenants = self._rpc.get_tenants()
          except arista_exc.AristaRpcError:
              LOG.warning(EOS_UNREACHABLE_MSG)
              self._force_sync = True
              return
  
          db_tenants = db.get_tenants()
  
          if not db_tenants and eos_tenants:
              # No tenants configured in Neutron. Clear all EOS state
              try:
                  self._rpc.delete_this_region()
                  msg = _('No Tenants configured in Neutron DB. But %d '
                          'tenants discovered in EOS during synchronization.'
                          'Entire EOS region is cleared') % len(eos_tenants)
                  LOG.info(msg)
                  # Re-register with EOS so that the timestamp is updated.
                  self._rpc.register_with_eos()
                  # Region has been completely cleaned. So there is nothing to
                  # synchronize
                  self._force_sync = False
              except arista_exc.AristaRpcError:
                  LOG.warning(EOS_UNREACHABLE_MSG)
                  self._force_sync = True
              return
  
          # Delete tenants that are in EOS, but not in the database
          tenants_to_delete = frozenset(eos_tenants.keys()).difference(
              db_tenants.keys())
  
          if tenants_to_delete:
              try:
                  self._rpc.delete_tenant_bulk(tenants_to_delete)
              except arista_exc.AristaRpcError:
                  LOG.warning(EOS_UNREACHABLE_MSG)
                  self._force_sync = True
                  return
  
          # None of the commands have failed till now. But if subsequent
          # operations fail, then force_sync is set to true
          self._force_sync = False
  
          for tenant in db_tenants:
              db_nets = db.get_networks(tenant)
              db_vms = db.get_vms(tenant)
              eos_nets = self._get_eos_networks(eos_tenants, tenant)
              eos_vms = self._get_eos_vms(eos_tenants, tenant)
  
              db_nets_key_set = frozenset(db_nets.keys())
              db_vms_key_set = frozenset(db_vms.keys())
              eos_nets_key_set = frozenset(eos_nets.keys())
              eos_vms_key_set = frozenset(eos_vms.keys())
  
              # Find the networks that are present on EOS, but not in Neutron DB
              nets_to_delete = eos_nets_key_set.difference(db_nets_key_set)
  
              # Find the VMs that are present on EOS, but not in Neutron DB
              vms_to_delete = eos_vms_key_set.difference(db_vms_key_set)
  
              # Find the Networks that are present in Neutron DB, but not on EOS
              nets_to_update = db_nets_key_set.difference(eos_nets_key_set)
  
              # Find the VMs that are present in Neutron DB, but not on EOS
              vms_to_update = db_vms_key_set.difference(eos_vms_key_set)
  
              try:
                  if vms_to_delete:
                      self._rpc.delete_vm_bulk(tenant, vms_to_delete)
                  if nets_to_delete:
                      self._rpc.delete_network_bulk(tenant, nets_to_delete)
                  if nets_to_update:
                      # Create a dict of networks keyed by id.
                      neutron_nets = dict(
                          (network['id'], network) for network in
                          self._ndb.get_all_networks_for_tenant(tenant)
                      )
  
                      networks = [
                          {'network_id': net_id,
                           'segmentation_id':
                              db_nets[net_id]['segmentationTypeId'],
                           'network_name':
                              neutron_nets.get(net_id, {'name': ''})['name'], }
                          for net_id in nets_to_update
                      ]
                      self._rpc.create_network_bulk(tenant, networks)
                  if vms_to_update:
                      # Filter the ports to only the vms that we are interested
                      # in.
                      vm_ports = [
                          port for port in self._ndb.get_all_ports_for_tenant(
                              tenant) if port['device_id'] in vms_to_update
                      ]
                      self._rpc.create_vm_port_bulk(tenant, vm_ports, db_vms)
              except arista_exc.AristaRpcError:
                  LOG.warning(EOS_UNREACHABLE_MSG)
                  self._force_sync = True
  
      def _get_eos_networks(self, eos_tenants, tenant):
          networks = {}
          if eos_tenants and tenant in eos_tenants:
              networks = eos_tenants[tenant]['tenantNetworks']
          return networks
  
      def _get_eos_vms(self, eos_tenants, tenant):
          vms = {}
          if eos_tenants and tenant in eos_tenants:
              vms = eos_tenants[tenant]['tenantVmInstances']
          return vms
  
  
  class AristaDriver(driver_api.MechanismDriver):
      """Ml2 Mechanism driver for Arista networking hardware.
  
      Remembers all networks and VMs that are provisioned on Arista Hardware.
      Does not send network provisioning request if the network has already been
      provisioned before for the given port.
      """
      def __init__(self, rpc=None):
  
          self.rpc = rpc or AristaRPCWrapper()
          self.db_nets = db.AristaProvisionedNets()
          self.db_vms = db.AristaProvisionedVms()
          self.db_tenants = db.AristaProvisionedTenants()
          self.ndb = db.NeutronNets()
  
          confg = cfg.CONF.ml2_arista
          self.segmentation_type = db.VLAN_SEGMENTATION
          self.timer = None
          self.eos = SyncService(self.rpc, self.ndb)
          self.sync_timeout = confg['sync_interval']
          self.eos_sync_lock = threading.Lock()
  
      def initialize(self):
          self.rpc.register_with_eos()
          self._cleanup_db()
          self.rpc.check_cli_commands()
          # Registering with EOS updates self.rpc.region_updated_time. Clear it
          # to force an initial sync
          self.rpc.clear_region_updated_time()
          self._synchronization_thread()
  
      def create_network_precommit(self, context):
          """Remember the tenant, and network information."""
  
          network = context.current
          segments = context.network_segments
          network_id = network['id']
          tenant_id = network['tenant_id']
          segmentation_id = segments[0]['segmentation_id']
          with self.eos_sync_lock:
              db.remember_tenant(tenant_id)
              db.remember_network(tenant_id,
                                  network_id,
                                  segmentation_id)
  
      def create_network_postcommit(self, context):
          """Provision the network on the Arista Hardware."""
  
          network = context.current
          network_id = network['id']
          network_name = network['name']
          tenant_id = network['tenant_id']
          segments = context.network_segments
          vlan_id = segments[0]['segmentation_id']
          with self.eos_sync_lock:
              if db.is_network_provisioned(tenant_id, network_id):
                  try:
                      network_dict = {
                          'network_id': network_id,
                          'segmentation_id': vlan_id,
                          'network_name': network_name}
                      self.rpc.create_network(tenant_id, network_dict)
                  except arista_exc.AristaRpcError:
                      LOG.info(EOS_UNREACHABLE_MSG)
                      raise ml2_exc.MechanismDriverError()
              else:
                  msg = _('Network %s is not created as it is not found in'
                          'Arista DB') % network_id
                  LOG.info(msg)
  
      def update_network_precommit(self, context):
          """At the moment we only support network name change
  
          Any other change in network is not supported at this time.
          We do not store the network names, therefore, no DB store
          action is performed here.
          """
          new_network = context.current
          orig_network = context.original
          if new_network['name'] != orig_network['name']:
              msg = _('Network name changed to %s') % new_network['name']
              LOG.info(msg)
  
      def update_network_postcommit(self, context):
          """At the moment we only support network name change
  
          If network name is changed, a new network create request is
          sent to the Arista Hardware.
          """
          new_network = context.current
          orig_network = context.original
          if new_network['name'] != orig_network['name']:
              network_id = new_network['id']
              network_name = new_network['name']
              tenant_id = new_network['tenant_id']
              vlan_id = new_network['provider:segmentation_id']
              with self.eos_sync_lock:
                  if db.is_network_provisioned(tenant_id, network_id):
                      try:
                          network_dict = {
                              'network_id': network_id,
                              'segmentation_id': vlan_id,
                              'network_name': network_name}
                          self.rpc.create_network(tenant_id, network_dict)
                      except arista_exc.AristaRpcError:
                          LOG.info(EOS_UNREACHABLE_MSG)
                          raise ml2_exc.MechanismDriverError()
                  else:
                      msg = _('Network %s is not updated as it is not found in'
                              'Arista DB') % network_id
                      LOG.info(msg)
  
      def delete_network_precommit(self, context):
          """Delete the network infromation from the DB."""
          network = context.current
          network_id = network['id']
          tenant_id = network['tenant_id']
          with self.eos_sync_lock:
              if db.is_network_provisioned(tenant_id, network_id):
                  db.forget_network(tenant_id, network_id)
              # if necessary, delete tenant as well.
              self.delete_tenant(tenant_id)
  
      def delete_network_postcommit(self, context):
          """Send network delete request to Arista HW."""
          network = context.current
          network_id = network['id']
          tenant_id = network['tenant_id']
          with self.eos_sync_lock:
  
              # Succeed deleting network in case EOS is not accessible.
              # EOS state will be updated by sync thread once EOS gets
              # alive.
              try:
                  self.rpc.delete_network(tenant_id, network_id)
              except arista_exc.AristaRpcError:
                  LOG.info(EOS_UNREACHABLE_MSG)
                  raise ml2_exc.MechanismDriverError()
  
      def create_port_precommit(self, context):
          """Remember the infromation about a VM and its ports
  
          A VM information, along with the physical host information
          is saved.
          """
          port = context.current
          device_id = port['device_id']
          device_owner = port['device_owner']
          host = context.host
  
          # device_id and device_owner are set on VM boot
          is_vm_boot = device_id and device_owner
          if host and is_vm_boot:
              port_id = port['id']
              network_id = port['network_id']
              tenant_id = port['tenant_id']
              with self.eos_sync_lock:
                  db.remember_vm(device_id, host, port_id,
                                 network_id, tenant_id)
  
      def create_port_postcommit(self, context):
          """Plug a physical host into a network.
  
          Send provisioning request to Arista Hardware to plug a host
          into appropriate network.
          """
          port = context.current
          device_id = port['device_id']
          device_owner = port['device_owner']
          host = context.host
  
          # device_id and device_owner are set on VM boot
          is_vm_boot = device_id and device_owner
          if host and is_vm_boot:
              port_id = port['id']
              port_name = port['name']
              network_id = port['network_id']
              tenant_id = port['tenant_id']
              with self.eos_sync_lock:
                  hostname = self._host_name(host)
                  vm_provisioned = db.is_vm_provisioned(device_id,
                                                        host,
                                                        port_id,
                                                        network_id,
                                                        tenant_id)
                  net_provisioned = db.is_network_provisioned(tenant_id,
                                                              network_id)
                  if vm_provisioned and net_provisioned:
                      try:
                          self.rpc.plug_port_into_network(device_id,
                                                          hostname,
                                                          port_id,
                                                          network_id,
                                                          tenant_id,
                                                          port_name,
                                                          device_owner)
                      except arista_exc.AristaRpcError:
                          LOG.info(EOS_UNREACHABLE_MSG)
                          raise ml2_exc.MechanismDriverError()
                  else:
                      msg = _('VM %s is not created as it is not found in '
                              'Arista DB') % device_id
                      LOG.info(msg)
  
      def update_port_precommit(self, context):
          """Update the name of a given port.
  
          At the moment we only support port name change.
          Any other change to port is not supported at this time.
          We do not store the port names, therefore, no DB store
          action is performed here.
          """
          new_port = context.current
          orig_port = context.original
          if new_port['name'] != orig_port['name']:
              msg = _('Port name changed to %s') % new_port['name']
              LOG.info(msg)
  
      def update_port_postcommit(self, context):
          """Update the name of a given port in EOS.
  
          At the moment we only support port name change
          Any other change to port is not supported at this time.
          """
          port = context.current
          orig_port = context.original
          if port['name'] == orig_port['name']:
              # nothing to do
              return
  
          device_id = port['device_id']
          device_owner = port['device_owner']
          host = context.host
          is_vm_boot = device_id and device_owner
  
          if host and is_vm_boot:
              port_id = port['id']
              port_name = port['name']
              network_id = port['network_id']
              tenant_id = port['tenant_id']
              with self.eos_sync_lock:
                  hostname = self._host_name(host)
                  segmentation_id = db.get_segmentation_id(tenant_id,
                                                           network_id)
                  vm_provisioned = db.is_vm_provisioned(device_id,
                                                        host,
                                                        port_id,
                                                        network_id,
                                                        tenant_id)
                  net_provisioned = db.is_network_provisioned(tenant_id,
                                                              network_id,
                                                              segmentation_id)
                  if vm_provisioned and net_provisioned:
                      try:
                          self.rpc.plug_port_into_network(device_id,
                                                          hostname,
                                                          port_id,
                                                          network_id,
                                                          tenant_id,
                                                          port_name,
                                                          device_owner)
                      except arista_exc.AristaRpcError:
                          LOG.info(EOS_UNREACHABLE_MSG)
                          raise ml2_exc.MechanismDriverError()
                  else:
                      msg = _('VM %s is not updated as it is not found in '
                              'Arista DB') % device_id
                      LOG.info(msg)
  
      def delete_port_precommit(self, context):
          """Delete information about a VM and host from the DB."""
          port = context.current
  
          host_id = context.host
          device_id = port['device_id']
          tenant_id = port['tenant_id']
          network_id = port['network_id']
          port_id = port['id']
          with self.eos_sync_lock:
              if db.is_vm_provisioned(device_id, host_id, port_id,
                                      network_id, tenant_id):
                  db.forget_vm(device_id, host_id, port_id,
                               network_id, tenant_id)
              # if necessary, delete tenant as well.
              self.delete_tenant(tenant_id)
  
      def delete_port_postcommit(self, context):
          """unPlug a physical host from a network.
  
          Send provisioning request to Arista Hardware to unplug a host
          from appropriate network.
          """
          port = context.current
          device_id = port['device_id']
          host = context.host
          port_id = port['id']
          network_id = port['network_id']
          tenant_id = port['tenant_id']
          device_owner = port['device_owner']
  
          try:
              with self.eos_sync_lock:
                  hostname = self._host_name(host)
                  if device_owner == n_const.DEVICE_OWNER_DHCP:
                      self.rpc.unplug_dhcp_port_from_network(device_id,
                                                             hostname,
                                                             port_id,
                                                             network_id,
                                                             tenant_id)
                  else:
                      self.rpc.unplug_host_from_network(device_id,
                                                        hostname,
                                                        port_id,
                                                        network_id,
                                                        tenant_id)
          except arista_exc.AristaRpcError:
              LOG.info(EOS_UNREACHABLE_MSG)
              raise ml2_exc.MechanismDriverError()
  
      def delete_tenant(self, tenant_id):
          """delete a tenant from DB.
  
          A tenant is deleted only if there is no network or VM configured
          configured for this tenant.
          """
          objects_for_tenant = (db.num_nets_provisioned(tenant_id) +
                                db.num_vms_provisioned(tenant_id))
          if not objects_for_tenant:
              db.forget_tenant(tenant_id)
  
      def _host_name(self, hostname):
          fqdns_used = cfg.CONF.ml2_arista['use_fqdn']
          return hostname if fqdns_used else hostname.split('.')[0]
  
      def _synchronization_thread(self):
          with self.eos_sync_lock:
              self.eos.synchronize()
  
          self.timer = threading.Timer(self.sync_timeout,
                                       self._synchronization_thread)
          self.timer.start()
  
      def stop_synchronization_thread(self):
          if self.timer:
              self.timer.cancel()
              self.timer = None
  
      def _cleanup_db(self):
          """Clean up any uncessary entries in our DB."""
          db_tenants = db.get_tenants()
          for tenant in db_tenants:
              neutron_nets = self.ndb.get_all_networks_for_tenant(tenant)
              neutron_nets_id = []
              for net in neutron_nets:
                  neutron_nets_id.append(net['id'])
              db_nets = db.get_networks(tenant)
              for net_id in db_nets.keys():
                  if net_id not in neutron_nets_id:
                      db.forget_network(tenant, net_id)
  