kytos-ng / topology

main.py

"""Main module of kytos/topology Kytos Network Application.

Manage the network topology
"""
import time
from threading import Lock

from flask import jsonify, request
from werkzeug.exceptions import BadRequest, UnsupportedMediaType

from kytos.core import KytosEvent, KytosNApp, log, rest
from kytos.core.exceptions import KytosLinkCreationError
from kytos.core.helpers import listen_to
from kytos.core.interface import Interface
from kytos.core.link import Link
from kytos.core.switch import Switch
from napps.kytos.topology import settings
from napps.kytos.topology.exceptions import RestoreError
from napps.kytos.topology.models import Topology
from napps.kytos.topology.storehouse import StoreHouse

DEFAULT_LINK_UP_TIMER = 10


class Main(KytosNApp):  # pylint: disable=too-many-public-methods
    """Main class of kytos/topology NApp.

    This class is the entry point for this napp.
    """

    def setup(self):
        """Initialize the NApp's links list."""
        self.links = {}
        self.store_items = {}
        self.intf_available_tags = {}
        self.link_up_timer = getattr(settings, 'LINK_UP_TIMER',
                                     DEFAULT_LINK_UP_TIMER)

        self.verify_storehouse('switches')
        self.verify_storehouse('interfaces')
        self.verify_storehouse('links')

        self.storehouse = StoreHouse(self.controller)

        self._lock = Lock()
        self._links_lock = Lock()

    # pylint: disable=unused-argument,arguments-differ
    @listen_to('kytos/storehouse.loaded')
    def execute(self, event=None):
        """Execute once when the napp is running."""
        with self._lock:
            self._load_network_status()

    def shutdown(self):
        """Do nothing."""
        log.info('NApp kytos/topology shutting down.')

    @staticmethod
    def _get_metadata():
        """Return a JSON with metadata."""
        try:
            metadata = request.get_json()
            content_type = request.content_type
        except BadRequest as err:
            result = 'The request body is not a well-formed JSON.'
            raise BadRequest(result) from err
        if content_type is None:
            result = 'The request body is empty.'
            raise BadRequest(result)
        if metadata is None:
            if content_type != 'application/json':
                result = ('The content type must be application/json '
                          f'(received {content_type}).')
            else:
                result = 'Metadata is empty.'
            raise UnsupportedMediaType(result)
        return metadata

    def _get_link_or_create(self, endpoint_a, endpoint_b):
        """Get an existing link or create a new one.

        Returns:
            Tuple(Link, bool): Link and a boolean whether it has been created.
        """
        new_link = Link(endpoint_a, endpoint_b)

        for link in self.links.values():
            if new_link == link:
                return (link, False)

        self.links[new_link.id] = new_link
        return (new_link, True)

    def _get_switches_dict(self):
        """Return a dictionary with the known switches."""
        switches = {'switches': {}}
        for idx, switch in enumerate(self.controller.switches.values()):
            switch_data = switch.as_dict()
            if not all(key in switch_data['metadata']
                       for key in ('lat', 'lng')):
                # Switches are initialized somewhere in the ocean
                switch_data['metadata']['lat'] = str(0.0)
                switch_data['metadata']['lng'] = str(-30.0+idx*10.0)
            switches['switches'][switch.id] = switch_data
        return switches

    def _get_links_dict(self):
        """Return a dictionary with the known links."""
        return {'links': {link.id: link.as_dict() for link in
                          self.links.values()}}

    def _get_links_dict_with_tags(self):
        """Return a dict with the known links with stored available_tags."""
        links = {}
        for link in self.links.values():
            link_dict = link.as_dict()
            endpoint_a = link_dict["endpoint_a"]
            endpoint_b = link_dict["endpoint_b"]
            for endpoint in (endpoint_a, endpoint_b):
                if endpoint["id"] in self.intf_available_tags:
                    endpoint["available_tags"] = self.intf_available_tags[
                        endpoint["id"]
                    ]
            links[link.id] = link_dict
        return {"links": links}

    def _get_topology_dict(self):
        """Return a dictionary with the known topology."""
        return {'topology': {**self._get_switches_dict(),
                             **self._get_links_dict()}}

    def _get_topology(self):
        """Return an object representing the topology."""
        return Topology(self.controller.switches, self.links)

    def _get_link_from_interface(self, interface):
        """Return the link of the interface, or None if it does not exist."""
        for link in self.links.values():
            if interface in (link.endpoint_a, link.endpoint_b):
                return link
        return None

    @staticmethod
    def _load_intf_available_tags(interface, intf_dict):
        """Load interface available tags given its dict."""
        has_available_tags = "available_tags" in intf_dict
        if has_available_tags:
            interface.set_available_tags(intf_dict["available_tags"])
        return has_available_tags

    def _load_link(self, link_att):
        dpid_a = link_att['endpoint_a']['switch']
        dpid_b = link_att['endpoint_b']['switch']
        port_a = link_att['endpoint_a']['port_number']
        port_b = link_att['endpoint_b']['port_number']
        link_str = f'{dpid_a}:{port_a}-{dpid_b}:{port_b}'
        log.info(f'Loading link from storehouse {link_str}')

        try:
            switch_a = self.controller.switches[dpid_a]
            switch_b = self.controller.switches[dpid_b]
            interface_a = switch_a.interfaces[port_a]
            interface_b = switch_b.interfaces[port_b]
        except Exception as err:
            error = f'Fail to load endpoints for link {link_str}: {err}'
            raise RestoreError(error) from err

        with self._links_lock:
            link, _ = self._get_link_or_create(interface_a, interface_b)

        if link_att['enabled']:
            link.enable()
        else:
            link.disable()

        interface_a.update_link(link)
        interface_b.update_link(link)
        interface_a.nni = True
        interface_b.nni = True
        for interface, interface_dict in (
            (interface_a, link_att["endpoint_a"]),
            (interface_b, link_att["endpoint_b"]),
        ):
            if self._load_intf_available_tags(interface, interface_dict):
                log.info(
                    f"Loaded {len(interface.available_tags)}"
                    f" available tags for {interface.id}"
                )
        self.update_instance_metadata(link)

    def _load_switch(self, switch_id, switch_att):
        log.info(f'Loading switch from storehouse dpid={switch_id}')
        switch = self.controller.get_switch_or_create(switch_id)
        if switch_att['enabled']:
            switch.enable()
        else:
            switch.disable()
        switch.description['manufacturer'] = switch_att.get('manufacturer', '')
        switch.description['hardware'] = switch_att.get('hardware', '')
        switch.description['software'] = switch_att.get('software')
        switch.description['serial'] = switch_att.get('serial', '')
        switch.description['data_path'] = switch_att.get('data_path', '')
        self.update_instance_metadata(switch)

        for iface_id, iface_att in switch_att.get('interfaces', {}).items():
            log.info(f'Loading interface iface_id={iface_id}')
            interface = switch.update_or_create_interface(
                            port_no=iface_att['port_number'],
                            name=iface_att['name'],
                            address=iface_att.get('mac', None),
                            speed=iface_att.get('speed', None))
            if iface_att['enabled']:
                interface.enable()
            else:
                interface.disable()
            interface.lldp = iface_att['lldp']
            self.update_instance_metadata(interface)
            name = 'kytos/topology.port.created'
            event = KytosEvent(name=name, content={
                                              'switch': switch_id,
                                              'port': interface.port_number,
                                              'port_description': {
                                                  'alias': interface.name,
                                                  'mac': interface.address,
                                                  'state': interface.state
                                                  }
                                              })
            self.controller.buffers.app.put(event)

    # pylint: disable=attribute-defined-outside-init
    def _load_network_status(self):
        """Load network status saved in storehouse."""
        try:
            status = self.storehouse.get_data()
        except FileNotFoundError as error:
            log.error(f'Fail to load network status from storehouse: {error}')
            return

        if not status:
            log.info('There is no status saved to restore.')
            return

        switches = status['network_status']['switches']
        links = status['network_status']['links']

        failed_switches = {}
        log.debug(f"_load_network_status switches={switches}")
        for switch_id, switch_att in switches.items():
            try:
                self._load_switch(switch_id, switch_att)
            # pylint: disable=broad-except
            except Exception as err:
                failed_switches[switch_id] = err
                log.error(f'Error loading switch: {err}')

        failed_links = {}
        log.debug(f"_load_network_status links={links}")
        for link_id, link_att in links.items():
            try:
                self._load_link(link_att)
            # pylint: disable=broad-except
            except Exception as err:
                failed_links[link_id] = err
                log.error(f'Error loading link {link_id}: {err}')

        name = 'kytos/topology.topology_loaded'
        event = KytosEvent(
            name=name,
            content={
                'topology': self._get_topology(),
                'failed_switches': failed_switches,
                'failed_links': failed_links
            })
        self.controller.buffers.app.put(event)

    @rest('v3/')
    def get_topology(self):
        """Return the latest known topology.

        This topology is updated when there are network events.
        """
        return jsonify(self._get_topology_dict())

    # Switch related methods
    @rest('v3/switches')
    def get_switches(self):
        """Return a json with all the switches in the topology."""
        return jsonify(self._get_switches_dict())

    @rest('v3/switches/<dpid>/enable', methods=['POST'])
    def enable_switch(self, dpid):
        """Administratively enable a switch in the topology."""
        try:
            self.controller.switches[dpid].enable()
        except KeyError:
            return jsonify("Switch not found"), 404

        log.info(f"Storing administrative state from switch {dpid}"
                 " to enabled.")
        self.save_status_on_storehouse()
        self.notify_switch_enabled(dpid)
        self.notify_topology_update()
        return jsonify("Operation successful"), 201

    @rest('v3/switches/<dpid>/disable', methods=['POST'])
    def disable_switch(self, dpid):
        """Administratively disable a switch in the topology."""
        try:
            self.controller.switches[dpid].disable()
        except KeyError:
            return jsonify("Switch not found"), 404

        log.info(f"Storing administrative state from switch {dpid}"
                 " to disabled.")
        self.save_status_on_storehouse()
        self.notify_switch_disabled(dpid)
        self.notify_topology_update()
        return jsonify("Operation successful"), 201

    @rest('v3/switches/<dpid>/metadata')
    def get_switch_metadata(self, dpid):
        """Get metadata from a switch."""
        try:
            return jsonify({"metadata":
                            self.controller.switches[dpid].metadata}), 200
        except KeyError:
            return jsonify("Switch not found"), 404

    @rest('v3/switches/<dpid>/metadata', methods=['POST'])
    def add_switch_metadata(self, dpid):
        """Add metadata to a switch."""
        metadata = self._get_metadata()

        try:
            switch = self.controller.switches[dpid]
        except KeyError:
            return jsonify("Switch not found"), 404

        switch.extend_metadata(metadata)
        self.notify_metadata_changes(switch, 'added')
        return jsonify("Operation successful"), 201

    @rest('v3/switches/<dpid>/metadata/<key>', methods=['DELETE'])
    def delete_switch_metadata(self, dpid, key):
        """Delete metadata from a switch."""
        try:
            switch = self.controller.switches[dpid]
        except KeyError:
            return jsonify("Switch not found"), 404

        switch.remove_metadata(key)
        self.notify_metadata_changes(switch, 'removed')
        return jsonify("Operation successful"), 200

    # Interface related methods
    @rest('v3/interfaces')
    def get_interfaces(self):
        """Return a json with all the interfaces in the topology."""
        interfaces = {}
        switches = self._get_switches_dict()
        for switch in switches['switches'].values():
            for interface_id, interface in switch['interfaces'].items():
                interfaces[interface_id] = interface

        return jsonify({'interfaces': interfaces})

    @rest('v3/interfaces/switch/<dpid>/enable', methods=['POST'])

This code seems to be duplicated in your project.

    @rest('v3/interfaces/<interface_enable_id>/enable', methods=['POST'])
    def enable_interface(self, interface_enable_id=None, dpid=None):
        """Administratively enable interfaces in the topology."""
        if dpid is None:
            dpid = ":".join(interface_enable_id.split(":")[:-1])
        try:
            switch = self.controller.switches[dpid]
        except KeyError as exc:
            return jsonify(f"Switch not found: {exc}"), 404

        if interface_enable_id:
            interface_number = int(interface_enable_id.split(":")[-1])

            try:
                switch.interfaces[interface_number].enable()
            except KeyError:
                msg = f"Switch {dpid} interface {interface_number} not found"
                return jsonify(msg), 404
        else:
            for interface in switch.interfaces.values():
                interface.enable()
        log.info("Storing administrative state for enabled interfaces.")
        self.save_status_on_storehouse()
        self.notify_topology_update()
        return jsonify("Operation successful"), 200

    @rest('v3/interfaces/switch/<dpid>/disable', methods=['POST'])

This code seems to be duplicated in your project.

    @rest('v3/interfaces/<interface_disable_id>/disable', methods=['POST'])
    def disable_interface(self, interface_disable_id=None, dpid=None):
        """Administratively disable interfaces in the topology."""
        if dpid is None:
            dpid = ":".join(interface_disable_id.split(":")[:-1])
        try:
            switch = self.controller.switches[dpid]
        except KeyError as exc:
            return jsonify(f"Switch not found: {exc}"), 404

        if interface_disable_id:
            interface_number = int(interface_disable_id.split(":")[-1])

            try:
                switch.interfaces[interface_number].disable()
            except KeyError:
                msg = f"Switch {dpid} interface {interface_number} not found"
                return jsonify(msg), 404
        else:
            for interface in switch.interfaces.values():
                interface.disable()
        log.info("Storing administrative state for disabled interfaces.")
        self.save_status_on_storehouse()
        self.notify_topology_update()
        return jsonify("Operation successful"), 200

    @rest('v3/interfaces/<interface_id>/metadata')
    def get_interface_metadata(self, interface_id):
        """Get metadata from an interface."""
        switch_id = ":".join(interface_id.split(":")[:-1])
        interface_number = int(interface_id.split(":")[-1])
        try:
            switch = self.controller.switches[switch_id]
        except KeyError:
            return jsonify("Switch not found"), 404

        try:
            interface = switch.interfaces[interface_number]
        except KeyError:
            return jsonify("Interface not found"), 404

        return jsonify({"metadata": interface.metadata}), 200

    @rest('v3/interfaces/<interface_id>/metadata', methods=['POST'])

This code seems to be duplicated in your project.

    def add_interface_metadata(self, interface_id):
        """Add metadata to an interface."""
        metadata = self._get_metadata()
        switch_id = ":".join(interface_id.split(":")[:-1])
        interface_number = int(interface_id.split(":")[-1])
        try:
            switch = self.controller.switches[switch_id]
        except KeyError:
            return jsonify("Switch not found"), 404

        try:
            interface = switch.interfaces[interface_number]
        except KeyError:
            return jsonify("Interface not found"), 404

        interface.extend_metadata(metadata)
        self.notify_metadata_changes(interface, 'added')
        return jsonify("Operation successful"), 201

    @rest('v3/interfaces/<interface_id>/metadata/<key>', methods=['DELETE'])

This code seems to be duplicated in your project.

    def delete_interface_metadata(self, interface_id, key):
        """Delete metadata from an interface."""
        switch_id = ":".join(interface_id.split(":")[:-1])
        interface_number = int(interface_id.split(":")[-1])

        try:
            switch = self.controller.switches[switch_id]
        except KeyError:
            return jsonify("Switch not found"), 404

        try:
            interface = switch.interfaces[interface_number]
        except KeyError:
            return jsonify("Interface not found"), 404

        if interface.remove_metadata(key) is False:
            return jsonify("Metadata not found"), 404

        self.notify_metadata_changes(interface, 'removed')
        return jsonify("Operation successful"), 200

    # Link related methods
    @rest('v3/links')
    def get_links(self):
        """Return a json with all the links in the topology.

        Links are connections between interfaces.
        """
        return jsonify(self._get_links_dict()), 200

    @rest('v3/links/<link_id>/enable', methods=['POST'])
    def enable_link(self, link_id):
        """Administratively enable a link in the topology."""
        try:
            with self._links_lock:
                self.links[link_id].enable()
        except KeyError:
            return jsonify("Link not found"), 404
        self.save_status_on_storehouse()
        self.notify_link_status_change(
            self.links[link_id],
            reason='link enabled'
        )
        self.notify_topology_update()
        return jsonify("Operation successful"), 201

    @rest('v3/links/<link_id>/disable', methods=['POST'])
    def disable_link(self, link_id):
        """Administratively disable a link in the topology."""
        try:
            with self._links_lock:
                self.links[link_id].disable()
        except KeyError:
            return jsonify("Link not found"), 404
        self.save_status_on_storehouse()
        self.notify_link_status_change(
            self.links[link_id],
            reason='link disabled'
        )
        self.notify_topology_update()
        return jsonify("Operation successful"), 201

    @rest('v3/links/<link_id>/metadata')
    def get_link_metadata(self, link_id):
        """Get metadata from a link."""
        try:
            return jsonify({"metadata": self.links[link_id].metadata}), 200
        except KeyError:
            return jsonify("Link not found"), 404

    @rest('v3/links/<link_id>/metadata', methods=['POST'])
    def add_link_metadata(self, link_id):
        """Add metadata to a link."""
        metadata = self._get_metadata()
        try:
            link = self.links[link_id]
        except KeyError:
            return jsonify("Link not found"), 404

        link.extend_metadata(metadata)
        self.notify_metadata_changes(link, 'added')
        return jsonify("Operation successful"), 201

    @rest('v3/links/<link_id>/metadata/<key>', methods=['DELETE'])
    def delete_link_metadata(self, link_id, key):
        """Delete metadata from a link."""
        try:
            link = self.links[link_id]
        except KeyError:
            return jsonify("Link not found"), 404

        if link.remove_metadata(key) is False:
            return jsonify("Metadata not found"), 404

        self.notify_metadata_changes(link, 'removed')
        return jsonify("Operation successful"), 200

    @listen_to("kytos/.*.link_available_tags")
    def on_link_available_tags(self, event):
        """Handle on_link_available_tags."""
        with self._links_lock:
            self.handle_on_link_available_tags(event.content.get("link"))

    def handle_on_link_available_tags(self, link):
        """Handle on_link_available_tags."""
        if link.id not in self.links:
            return
        endpoint_a = self.links[link.id].endpoint_a
        endpoint_b = self.links[link.id].endpoint_b
        tags_a = [tag.value for tag in endpoint_a.available_tags]
        tags_b = [tag.value for tag in endpoint_b.available_tags]
        self.intf_available_tags[endpoint_a.id] = tags_a
        self.intf_available_tags[endpoint_b.id] = tags_b

        self.save_status_on_storehouse()

    @listen_to('.*.switch.(new|reconnected)')
    def on_new_switch(self, event):
        """Create a new Device on the Topology.

        Handle the event of a new created switch and update the topology with
        this new device. Also notify if the switch is enabled.
        """
        self.handle_new_switch(event)

    def handle_new_switch(self, event):
        """Create a new Device on the Topology."""
        switch = event.content['switch']
        switch.activate()
        log.debug('Switch %s added to the Topology.', switch.id)
        self.notify_topology_update()
        self.update_instance_metadata(switch)
        if switch.is_enabled():
            self.notify_switch_enabled(switch.id)

    @listen_to('.*.connection.lost')
    def on_connection_lost(self, event):
        """Remove a Device from the topology.

        Remove the disconnected Device and every link that has one of its
        interfaces.
        """
        self.handle_connection_lost(event)

    def handle_connection_lost(self, event):
        """Remove a Device from the topology."""
        switch = event.content['source'].switch
        if switch:
            switch.deactivate()
            log.debug('Switch %s removed from the Topology.', switch.id)
            self.notify_topology_update()

    def handle_interface_created(self, event):
        """Update the topology based on a Port Created event.

        It's handled as a link_up in case a switch send a
        created event again and it can be belong to a link.
        """
        interface = event.content['interface']

        with self._links_lock:
            if interface.id in self.intf_available_tags:
                available_tags = self.intf_available_tags[interface.id]
                interface_dict = {"available_tags": available_tags}
                if self._load_intf_available_tags(interface, interface_dict):
                    log.info(
                        f"Loaded {len(interface.available_tags)}"
                        f" available tags for {interface.id}"
                    )

        self.update_instance_metadata(interface)
        self.handle_interface_link_up(interface)

    @listen_to('.*.switch.interface.created')
    def on_interface_created(self, event):
        """Update the topology based on a Port Create event.

        It's handled as a link_up in case a switch send a
        created event again and it can be belong to a link.
        """
        self.handle_interface_created(event)

    def handle_interface_down(self, event):
        """Update the topology based on a Port Modify event.

        The event notifies that an interface was changed to 'down'.
        """
        interface = event.content['interface']
        interface.deactivate()
        self.handle_interface_link_down(interface)

    @listen_to('.*.switch.interface.deleted')
    def on_interface_deleted(self, event):
        """Update the topology based on a Port Delete event."""
        self.handle_interface_deleted(event)

    def handle_interface_deleted(self, event):
        """Update the topology based on a Port Delete event."""
        self.handle_interface_down(event)

    @listen_to('.*.switch.interface.link_up')
    def on_interface_link_up(self, event):
        """Update the topology based on a Port Modify event.

        The event notifies that an interface's link was changed to 'up'.
        """
        interface = event.content['interface']
        self.handle_interface_link_up(interface)

    def handle_interface_link_up(self, interface):
        """Update the topology based on a Port Modify event."""
        self.handle_link_up(interface)

    @listen_to('kytos/maintenance.end_switch')
    def on_switch_maintenance_end(self, event):
        """Handle the end of the maintenance of a switch."""
        self.handle_switch_maintenance_end(event)

    def handle_switch_maintenance_end(self, event):
        """Handle the end of the maintenance of a switch."""
        switches = event.content['switches']
        for switch in switches:
            switch.enable()
            switch.activate()
            for interface in switch.interfaces.values():
                interface.enable()
                self.handle_link_up(interface)

    def handle_link_up(self, interface):
        """Notify a link is up."""
        interface.activate()
        self.notify_topology_update()
        with self._links_lock:
            link = self._get_link_from_interface(interface)
        if not link:
            return
        if link.endpoint_a == interface:
            other_interface = link.endpoint_b
        else:
            other_interface = link.endpoint_a
        if other_interface.is_active() is False:
            return
        if link.is_active() is False:
            link.update_metadata('last_status_change', time.time())
            link.activate()

            # As each run of this method uses a different thread,
            # there is no risk this sleep will lock the NApp.
            time.sleep(self.link_up_timer)

            last_status_change = link.get_metadata('last_status_change')
            now = time.time()
            if link.is_active() and \
                    now - last_status_change >= self.link_up_timer:
                self.update_instance_metadata(link)
                self.notify_topology_update()
                self.notify_link_status_change(link, reason='link up')
        else:
            link.update_metadata('last_status_change', time.time())
            self.update_instance_metadata(link)
            self.notify_topology_update()
            self.notify_link_status_change(link, reason='link up')
        link.update_metadata('last_status_is_active', True)

    @listen_to('.*.switch.interface.link_down')
    def on_interface_link_down(self, event):
        """Update the topology based on a Port Modify event.

        The event notifies that an interface's link was changed to 'down'.
        """
        interface = event.content['interface']
        self.handle_interface_link_down(interface)

    def handle_interface_link_down(self, interface):
        """Update the topology based on an interface."""
        self.handle_link_down(interface)

    @listen_to('kytos/maintenance.start_switch')
    def on_switch_maintenance_start(self, event):
        """Handle the start of the maintenance of a switch."""
        self.handle_switch_maintenance_start(event)

    def handle_switch_maintenance_start(self, event):
        """Handle the start of the maintenance of a switch."""
        switches = event.content['switches']
        for switch in switches:
            switch.disable()
            switch.deactivate()
            for interface in switch.interfaces.values():
                interface.disable()
                if interface.is_active():
                    self.handle_link_down(interface)

    def handle_link_down(self, interface):
        """Notify a link is down."""
        link = self._get_link_from_interface(interface)
        if link and link.is_active():
            link.deactivate()
            link.update_metadata('last_status_change', time.time())
            link.update_metadata('last_status_is_active', False)
            self.notify_link_status_change(link, reason='link down')
        if link and not link.is_active():
            with self._links_lock:
                last_status = link.get_metadata('last_status_is_active')
                if last_status:
                    link.update_metadata('last_status_is_active', False)
                    link.update_metadata('last_status_change', time.time())
                    self.notify_link_status_change(link, reason='link down')
        interface.deactivate()
        self.notify_topology_update()

    @listen_to('.*.interface.is.nni')
    def on_add_links(self, event):
        """Update the topology with links related to the NNI interfaces."""
        self.add_links(event)

    def add_links(self, event):
        """Update the topology with links related to the NNI interfaces."""
        interface_a = event.content['interface_a']
        interface_b = event.content['interface_b']

        try:
            with self._links_lock:
                link, created = self._get_link_or_create(interface_a,
                                                         interface_b)
                interface_a.update_link(link)
                interface_b.update_link(link)

                link.endpoint_a = interface_a
                link.endpoint_b = interface_b

                interface_a.nni = True
                interface_b.nni = True

        except KytosLinkCreationError as err:
            log.error(f'Error creating link: {err}.')
            return

        if created:
            self.update_instance_metadata(link)
            link.update_metadata('last_status_is_active', True)
            self.notify_link_status_change(link, reason='link up')
            self.notify_topology_update()

    # def add_host(self, event):
    #    """Update the topology with a new Host."""

    #    interface = event.content['port']
    #    mac = event.content['reachable_mac']

    #    host = Host(mac)
    #    link = self.topology.get_link(interface.id)
    #    if link is not None:
    #        return

    #    self.topology.add_link(interface.id, host.id)
    #    self.topology.add_device(host)

    #    if settings.DISPLAY_FULL_DUPLEX_LINKS:
    #        self.topology.add_link(host.id, interface.id)

    @listen_to('.*.network_status.updated')
    def on_network_status_updated(self, event):
        """Handle *.network_status.updated events, specially from of_lldp."""
        content = event.content
        log.info(f"Storing the administrative state of the"
                 f" {content['attribute']} attribute to"
                 f" {content['state']} in the interfaces"
                 f" {content['interface_ids']}")
        self.handle_network_status_updated()

    def handle_network_status_updated(self) -> None:
        """Handle *.network_status.updated events, specially from of_lldp."""
        self.save_status_on_storehouse()

    def save_status_on_storehouse(self):
        """Save the network administrative status using storehouse."""
        with self._lock:
            status = self._get_switches_dict()
            status['id'] = 'network_status'
            status.update(self._get_links_dict_with_tags())
            self.storehouse.save_status(status)

    def notify_switch_enabled(self, dpid):
        """Send an event to notify that a switch is enabled."""
        name = 'kytos/topology.switch.enabled'
        event = KytosEvent(name=name, content={'dpid': dpid})
        self.controller.buffers.app.put(event)

    def notify_switch_disabled(self, dpid):
        """Send an event to notify that a switch is disabled."""
        name = 'kytos/topology.switch.disabled'
        event = KytosEvent(name=name, content={'dpid': dpid})
        self.controller.buffers.app.put(event)

    def notify_topology_update(self):
        """Send an event to notify about updates on the topology."""
        name = 'kytos/topology.updated'
        event = KytosEvent(name=name, content={'topology':
                                               self._get_topology()})
        self.controller.buffers.app.put(event)

    def notify_link_status_change(self, link, reason='not given'):
        """Send an event to notify about a status change on a link."""
        name = 'kytos/topology.'
        if link.is_active() and link.is_enabled():
            status = 'link_up'
        else:
            status = 'link_down'
        event = KytosEvent(
            name=name+status,
            content={
                'link': link,
                'reason': reason
            })
        self.controller.buffers.app.put(event)

    def notify_metadata_changes(self, obj, action):
        """Send an event to notify about metadata changes."""
        if isinstance(obj, Switch):
            entity = 'switch'
            entities = 'switches'
        elif isinstance(obj, Interface):
            entity = 'interface'
            entities = 'interfaces'
        elif isinstance(obj, Link):
            entity = 'link'
            entities = 'links'
        else:
            raise ValueError(
                'Invalid object, supported: Switch, Interface, Link'
            )

        self.save_metadata_on_store(obj, entities)

        name = f'kytos/topology.{entities}.metadata.{action}'
        event = KytosEvent(name=name, content={entity: obj,
                                               'metadata': obj.metadata})
        self.controller.buffers.app.put(event)
        log.debug(f'Metadata from {obj.id} was {action}.')

    @listen_to('.*.switch.port.created')
    def on_notify_port_created(self, event):
        """Notify when a port is created."""
        self.notify_port_created(event)

    def notify_port_created(self, event):
        """Notify when a port is created."""
        name = 'kytos/topology.port.created'
        event = KytosEvent(name=name, content=event.content)
        self.controller.buffers.app.put(event)

    def save_metadata_on_store(self, obj, entities):
        """Send to storehouse the data updated."""
        name = 'kytos.storehouse.update'
        store = self.store_items.get(entities)
        namespace = f'kytos.topology.{entities}.metadata'

        store.data[obj.id] = obj.metadata
        content = {'namespace': namespace,
                   'box_id': store.box_id,
                   'data': store.data,
                   'callback': self.update_instance}

        event = KytosEvent(name=name, content=content)
        self.controller.buffers.app.put(event)

    @staticmethod
    def update_instance(event, _data, error):
        """Display in Kytos console if the data was updated."""
        entities = event.content.get('namespace', '').split('.')[-2]
        if error:
            log.error(f'Error trying to update storehouse {entities}.')
        else:
            log.debug(f'Storehouse update to entities: {entities}.')

    def verify_storehouse(self, entities):
        """Request a list of box saved by specific entity."""
        name = 'kytos.storehouse.list'
        content = {'namespace': f'kytos.topology.{entities}.metadata',
                   'callback': self.request_retrieve_entities}
        event = KytosEvent(name=name, content=content)
        self.controller.buffers.app.put(event)
        log.info(f'verify data in storehouse for {entities}.')

    def request_retrieve_entities(self, event, data, _error):
        """Create a box or retrieve an existent box from storehouse."""
        msg = ''
        content = {'namespace': event.content.get('namespace'),
                   'callback': self.load_from_store,
                   'data': {}}

        if not data:
            name = 'kytos.storehouse.create'
            msg = 'Create new box in storehouse'
        else:
            name = 'kytos.storehouse.retrieve'
            content['box_id'] = data[0]
            msg = 'Retrieve data from storehouse.'

        event = KytosEvent(name=name, content=content)
        self.controller.buffers.app.put(event)
        log.debug(msg)

    def load_from_store(self, event, box, error):
        """Save the data retrived from storehouse."""
        entities = event.content.get('namespace', '').split('.')[-2]
        if error:
            log.error('Error while get a box from storehouse.')
        else:
            self.store_items[entities] = box
            log.debug('Data updated')

    def update_instance_metadata(self, obj):
        """Update object instance with saved metadata."""
        metadata = None
        if isinstance(obj, Interface):
            all_metadata = self.store_items.get('interfaces', None)
            if all_metadata:
                metadata = all_metadata.data.get(obj.id)
        elif isinstance(obj, Switch):
            all_metadata = self.store_items.get('switches', None)
            if all_metadata:
                metadata = all_metadata.data.get(obj.id)
        elif isinstance(obj, Link):
            all_metadata = self.store_items.get('links', None)
            if all_metadata:
                metadata = all_metadata.data.get(obj.id)
        if metadata:
            obj.extend_metadata(metadata)
            log.debug(f'Metadata to {obj.id} was updated')

    @listen_to('kytos/maintenance.start_link')
    def on_link_maintenance_start(self, event):
        """Deals with the start of links maintenance."""
        with self._links_lock:
            self.handle_link_maintenance_start(event)

    def handle_link_maintenance_start(self, event):
        """Deals with the start of links maintenance."""
        notify_links = []
        maintenance_links = event.content['links']
        for maintenance_link in maintenance_links:
            try:
                link = self.links[maintenance_link.id]
            except KeyError:
                continue
            notify_links.append(link)
        for link in notify_links:
            link.disable()
            link.deactivate()
            link.endpoint_a.deactivate()
            link.endpoint_b.deactivate()
            link.endpoint_a.disable()
            link.endpoint_b.disable()
            self.notify_link_status_change(link, reason='maintenance')

    @listen_to('kytos/maintenance.end_link')
    def on_link_maintenance_end(self, event):
        """Deals with the end of links maintenance."""
        with self._links_lock:
            self.handle_link_maintenance_end(event)

    def handle_link_maintenance_end(self, event):
        """Deals with the end of links maintenance."""
        notify_links = []
        maintenance_links = event.content['links']
        for maintenance_link in maintenance_links:
            try:
                link = self.links[maintenance_link.id]
            except KeyError:
                continue
            notify_links.append(link)
        for link in notify_links:
            link.enable()
            link.activate()
            link.endpoint_a.activate()
            link.endpoint_b.activate()
            link.endpoint_a.enable()
            link.endpoint_b.enable()
            self.notify_link_status_change(link, reason='maintenance')