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# Copyright (c) 2012 OpenStack Foundation
# All Rights Reserved.
#
#    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.

"""Functionality related to notifications common to multiple layers of
the system.
"""

from oslo.config import cfg

from nova.compute import instance_types
import nova.context
from nova import db
from nova.image import glance
from nova import network
from nova.network import model as network_model
from nova.openstack.common import excutils
from nova.openstack.common import log
from nova.openstack.common.notifier import api as notifier_api
from nova.openstack.common import timeutils
from nova import utils

LOG = log.getLogger(__name__)

notify_opts = [
    cfg.StrOpt('notify_on_state_change', default=None,
        help='If set, send compute.instance.update notifications on instance '
             'state changes.  Valid values are None for no notifications, '
             '"vm_state" for notifications on VM state changes, or '
             '"vm_and_task_state" for notifications on VM and task state '
             'changes.'),
    cfg.BoolOpt('notify_on_any_change', default=False,
        help='If set, send compute.instance.update notifications on instance '
             'state changes.  Valid values are False for no notifications, '
             'True for notifications on any instance changes.'),
    cfg.BoolOpt('notify_api_faults', default=False,
        help='If set, send api.fault notifications on caught exceptions '
             'in the API service.'),
]


CONF = cfg.CONF
CONF.register_opts(notify_opts)


def send_api_fault(url, status, exception):
    """Send an api.fault notification."""

    if not CONF.notify_api_faults:
        return

    payload = {'url': url, 'exception': str(exception), 'status': status}

    publisher_id = notifier_api.publisher_id("api")

    notifier_api.notify(None, publisher_id, 'api.fault', notifier_api.ERROR,
                        payload)


def send_update(context, old_instance, new_instance, service=None, host=None):
    """Send compute.instance.update notification to report any changes occurred
    in that instance
    """

    if not CONF.notify_on_any_change and not CONF.notify_on_state_change:
        # skip all this if updates are disabled
        return

    update_with_state_change = False

    old_vm_state = old_instance["vm_state"]
    new_vm_state = new_instance["vm_state"]
    old_task_state = old_instance["task_state"]
    new_task_state = new_instance["task_state"]

    # we should check if we need to send a state change or a regular
    # notification
    if old_vm_state != new_vm_state:
        # yes, the vm state is changing:
        update_with_state_change = True
    elif CONF.notify_on_state_change:
        if (CONF.notify_on_state_change.lower() == "vm_and_task_state" and
            old_task_state != new_task_state):
            # yes, the task state is changing:
            update_with_state_change = True

    if update_with_state_change:
        # send a notification with state changes
        # value of verify_states need not be True as the check for states is
        # already done here
        send_update_with_states(context, new_instance, old_vm_state,
                new_vm_state, old_task_state, new_task_state, service, host)

    else:
        try:
            _send_instance_update_notification(context, new_instance,
                    service=service, host=host)
        except Exception:
            LOG.exception(_("Failed to send state update notification"),
                    instance=new_instance)


def send_update_with_states(context, instance, old_vm_state, new_vm_state,
        old_task_state, new_task_state, service="compute", host=None,
        verify_states=False):
    """Send compute.instance.update notification to report changes if there
    are any, in the instance
    """

    if not CONF.notify_on_state_change:
        # skip all this if updates are disabled
        return

    fire_update = True
    # send update notification by default

    if verify_states:
        # check whether we need to send notification related to state changes
        fire_update = False
        # do not send notification if the conditions for vm and(or) task state
        # are not satisfied
        if old_vm_state != new_vm_state:
            # yes, the vm state is changing:
            fire_update = True
        elif CONF.notify_on_state_change:
            if (CONF.notify_on_state_change.lower() == "vm_and_task_state" and
                old_task_state != new_task_state):
                # yes, the task state is changing:
                fire_update = True

    if fire_update:
        # send either a state change or a regular notification
        try:
            _send_instance_update_notification(context, instance,
                    old_vm_state=old_vm_state, old_task_state=old_task_state,
                    new_vm_state=new_vm_state, new_task_state=new_task_state,
                    service=service, host=host)
        except Exception:
            LOG.exception(_("Failed to send state update notification"),
                    instance=instance)


def _send_instance_update_notification(context, instance, old_vm_state=None,
            old_task_state=None, new_vm_state=None, new_task_state=None,
            service="compute", host=None):
    """Send 'compute.instance.update' notification to inform observers
    about instance state changes"""

    payload = info_from_instance(context, instance, None, None)

    if not new_vm_state:
        new_vm_state = instance["vm_state"]
    if not new_task_state:
        new_task_state = instance["task_state"]

    states_payload = {
        "old_state": old_vm_state,
        "state": new_vm_state,
        "old_task_state": old_task_state,
        "new_task_state": new_task_state,
    }

    payload.update(states_payload)

    # add audit fields:
    (audit_start, audit_end) = audit_period_bounds(current_period=True)
    payload["audit_period_beginning"] = audit_start
    payload["audit_period_ending"] = audit_end

    # add bw usage info:
    bw = bandwidth_usage(instance, audit_start)
    payload["bandwidth"] = bw

    publisher_id = notifier_api.publisher_id(service, host)

    notifier_api.notify(context, publisher_id, 'compute.instance.update',
            notifier_api.INFO, payload)


def audit_period_bounds(current_period=False):
    """Get the start and end of the relevant audit usage period

    :param current_period: if True, this will generate a usage for the
        current usage period; if False, this will generate a usage for the
        previous audit period.
    """

    begin, end = utils.last_completed_audit_period()
    if current_period:
        audit_start = end
        audit_end = timeutils.utcnow()
    else:
        audit_start = begin
        audit_end = end

    return (audit_start, audit_end)


def bandwidth_usage(instance_ref, audit_start,
        ignore_missing_network_data=True):
    """Get bandwidth usage information for the instance for the
    specified audit period.
    """

    admin_context = nova.context.get_admin_context(read_deleted='yes')

    if (instance_ref.get('info_cache') and
        instance_ref['info_cache'].get('network_info') is not None):

        cached_info = instance_ref['info_cache']['network_info']
        nw_info = network_model.NetworkInfo.hydrate(cached_info)
    else:
        try:
            nw_info = network.API().get_instance_nw_info(admin_context,
                    instance_ref)
        except Exception:
            try:
                with excutils.save_and_reraise_exception():
                    LOG.exception(_('Failed to get nw_info'),
                                  instance=instance_ref)
            except Exception:
                if ignore_missing_network_data:
                    return
                raise

    macs = [vif['address'] for vif in nw_info]
    uuids = [instance_ref["uuid"]]

    bw_usages = db.bw_usage_get_by_uuids(admin_context, uuids, audit_start)
    bw_usages = [b for b in bw_usages if b.mac in macs]

    bw = {}

    for b in bw_usages:
        label = 'net-name-not-found-%s' % b['mac']
        for vif in nw_info:
            if vif['address'] == b['mac']:
                label = vif['network']['label']
                break

        bw[label] = dict(bw_in=b.bw_in, bw_out=b.bw_out)

    return bw


def image_meta(system_metadata):
    """Format image metadata for use in notifications from the instance
    system metadata.
    """
    image_meta = {}
    for md_key, md_value in system_metadata.iteritems():
        if md_key.startswith('image_'):
            image_meta[md_key[6:]] = md_value

    return image_meta


def info_from_instance(context, instance_ref, network_info,
                system_metadata, **kw):
    """Get detailed instance information for an instance which is common to all
    notifications.

    :param network_info: network_info provided if not None
    :param system_metadata: system_metadata DB entries for the instance,
    if not None.  *NOTE*: Currently unused here in trunk, but needed for
    potential custom modifications.
    """

    def null_safe_str(s):
        return str(s) if s else ''

    image_ref_url = glance.generate_image_url(instance_ref['image_ref'])

    instance_type = instance_types.extract_instance_type(instance_ref)
    instance_type_name = instance_type.get('name', '')

    if system_metadata is None:
        system_metadata = utils.metadata_to_dict(
                instance_ref['system_metadata'])

    instance_info = dict(
        # Owner properties
        tenant_id=instance_ref['project_id'],
        user_id=instance_ref['user_id'],

        # Identity properties
        instance_id=instance_ref['uuid'],
        display_name=instance_ref['display_name'],
        reservation_id=instance_ref['reservation_id'],
        hostname=instance_ref['hostname'],

        # Type properties
        instance_type=instance_type_name,
        instance_type_id=instance_ref['instance_type_id'],
        architecture=instance_ref['architecture'],

        # Capacity properties
        memory_mb=instance_ref['memory_mb'],
        disk_gb=instance_ref['root_gb'] + instance_ref['ephemeral_gb'],
        vcpus=instance_ref['vcpus'],
        # Note(dhellmann): This makes the disk_gb value redundant, but
        # we are keeping it for backwards-compatibility with existing
        # users of notifications.
        root_gb=instance_ref['root_gb'],
        ephemeral_gb=instance_ref['ephemeral_gb'],

        # Location properties
        host=instance_ref['host'],
        availability_zone=instance_ref['availability_zone'],

        # Date properties
        created_at=str(instance_ref['created_at']),
        # Nova's deleted vs terminated instance terminology is confusing,
        # this should be when the instance was deleted (i.e. terminated_at),
        # not when the db record was deleted. (mdragon)
        deleted_at=null_safe_str(instance_ref.get('terminated_at')),
        launched_at=null_safe_str(instance_ref.get('launched_at')),

        # Image properties
        image_ref_url=image_ref_url,
        os_type=instance_ref['os_type'],
        kernel_id=instance_ref['kernel_id'],
        ramdisk_id=instance_ref['ramdisk_id'],

        # Status properties
        state=instance_ref['vm_state'],
        state_description=null_safe_str(instance_ref.get('task_state')),

        # accessIPs
        access_ip_v4=instance_ref['access_ip_v4'],
        access_ip_v6=instance_ref['access_ip_v6'],
        )

    if network_info is not None:
        fixed_ips = []
        for vif in network_info:
            for ip in vif.fixed_ips():
                ip["label"] = vif["network"]["label"]
                fixed_ips.append(ip)
        instance_info['fixed_ips'] = fixed_ips

    # add image metadata
    image_meta_props = image_meta(system_metadata)
    instance_info["image_meta"] = image_meta_props

    # add instance metadata
    instance_info['metadata'] = instance_ref['metadata']

    instance_info.update(kw)
    return instance_info