__init__.py

import logging
import weakref
from itertools import chain, imap

import libvirt

from ccnode.host import Handler as HostHandler
from ccnode.tags import Tag, tag_inspector, get_tags
from ccnode.hypervisor import tags
from ccnode.hypervisor.lib import (
    DOMAIN_STATES, EVENTS, STORAGE_STATES,
    EventLoop as VirEventLoop,
)
from ccnode.hypervisor.domains import VirtualMachine
from ccnode.exc import UndefinedDomain


logger = logging.getLogger(__name__)


# FIXME find a way to refactor Handler and Hypervisor class
class Handler(HostHandler):
    def __init__(self, *args, **kwargs):
        """
        :param loop: MainLoop instance
        :param hypervisor_name: hypervisor name
        """
        self.hypervisor_name = kwargs.pop('hypervisor_name')
        HostHandler.__init__(self, *args, **kwargs)

        #: keep index of asynchronous calls
        self.async_calls = dict()

        self.timer = self.main.evloop.timer(.0, 5., self.virt_connect_cb)
        self.hypervisor = None
        self._virt_connected = False

        # register tags
        self.tag_db.add_tags(tag_inspector(tags, self))

    @property
    def virt_connected(self):
        return self._virt_connected

    @virt_connected.setter
    def virt_connected(self, value):
        self._virt_connected = value
        # update tags
        for tag in ('vir_status', 'sto', 'nvm', 'vmpaused', 'vmstarted',
                    'vmstopped', 'hvver', 'libvirtver', 'hv'):
            # TODO tag annoucement
            self.tag_db['__main__'][tag].calculate_value()

    def start(self):
        self.timer.start()
        HostHandler.start(self)

    def stop(self):
        self.timer.stop()
        if self.hypervisor is not None:
            self.hypervisor.stop()
        HostHandler.stop(self)

    def virt_connect_cb(self, *args):
        # initialize hypervisor instance
        try:
            self.hypervisor = Hypervisor(
                name=self.hypervisor_name,
                handler=self,
            )
        except libvirt.libvirtError:
            logger.exception('Error while connecting to libvirt')
            return

        self.virt_connected = True

        # register hypervisor storage tags
        for name, storage in self.hypervisor.storage.storages.iteritems():
            self.tag_db.add_tags((
                Tag('sto%s_state' % name, lambda: storage.state, 5, 5),
                Tag('sto%s_size' % name, lambda: storage.capacity, 5, 5),
                Tag('sto%s_free' % name, lambda: storage.available, 5, 5),
                Tag('sto%s_used' % name,
                    lambda: storage.capacity - storage.available, 5, 5),
            ))

        # register domains
        for dom in self.hypervisor.domains.itervalues():
            self.tag_db.add_sub_object(dom.name, dom.tags.itervalues())

        self.rpc_handler.update(dict(
            vm_define=self.vm_define,
            vm_undefine=self.vm_undefine,
            vm_export=self.vm_export,
            vm_stop=self.vm_stop,
            vm_start=self.vm_start,
            vm_suspend=self.vm_suspend,
            vm_resume=self.vm_resume,
        ))
        self.main.reset_handler('vm_define', self.vm_define)
        self.main.reset_handler('vm_undefine', self.vm_undefine)
        self.main.reset_handler('vm_export', self.vm_export)
        self.main.reset_handler('vm_stop', self.vm_stop)
        self.main.reset_handler('vm_destroy', self.vm_destroy)
        self.main.reset_handler('vm_start', self.vm_start)
        self.main.reset_handler('vm_suspend', self.vm_suspend)
        self.main.reset_handler('vm_resume', self.vm_resume)

        # if everything went fine, unregister the timer
        self.timer.stop()

    def virt_connect_restart(self):
        """Restart libvirt connection.

        This method might be called when libvirt connection is lost.
        """
        if not self.virt_connected:
            return

        logger.error('Connection to libvirt lost, trying to restart')
        # update connection state
        self.virt_connected = False
        # unregister tags that will be re registered later
        for storage in self.hypervisor.storage.storages:
            self.tag_db.remove_tags((
                'sto%s_state' % storage,
                'sto%s_size' % storage,
                'sto%s_free' % storage,
                'sto%s_used' % storage,
            ))
        # unregister sub objects (for the same reason)
        for sub_id in self.tag_db.keys():
            if sub_id == '__main__':
                continue
            self.tag_db.remove_sub_object(sub_id)
        # stop and delete hypervisor instance
        self.hypervisor.stop()
        self.hypervisor = None

        # remove handlers related to libvirt
        self.main.remove_handler('vm_define')
        self.main.remove_handler('vm_undefine')
        self.main.remove_handler('vm_export')
        self.main.remove_handler('vm_stop')
        self.main.remove_handler('vm_destroy')
        self.main.remove_handler('vm_start')
        self.main.remove_handler('vm_suspend')
        self.main.remove_handler('vm_resume')
        # launch connection timer
        self.timer.start()

    def iter_vms(self, vm_names):
        """Utility function to iterate over VM objects using their names."""
        if vm_names is None:
            return
        get_domain = self.hypervisor.domains.get
        for name in vm_names:
            dom = get_domain(name)
            if dom is not None:
                yield dom

    def vm_define(self, data, format='xml'):
        logger.debug('VM define')
        if format != 'xml':
            raise NotImplementedError('Format not supported')

        return self.hypervisor.vm_define(data)

    def vm_undefine(self, name):
        logger.debug('VM undefine %s', name)
        vm = self.hypervisor.domains.get(name)
        if vm is not None:
            vm.undefine()

    def vm_export(self, name, format='xml'):
        logger.debug('VM export %s', name)
        if format != 'xml':
            raise NotImplementedError('Format not supported')

        vm = self.hypervisor.domains.get(name)

        if vm is None:
            return

        return vm.lv_dom.XMLDesc(0)

    def vm_stop(self, name):
        logger.debug('VM stop %s', name)
        try:
            self.hypervisor.domains[name].stop()
        except libvirt.libvirtError:
            logger.exception('Error while stopping VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot stop VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_destroy(self, name):
        logger.debug('VM destroy %s', name)
        try:
            self.hypervisor.domains[name].destroy()
        except libvirt.libvirtError:
            logger.exception('Error while destroying VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot destroy VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_start(self, name):
        logger.debug('VM start %s', name)
        try:
            self.hypervisor.domains[name].start()
        except libvirt.libvirtError:
            logger.exception('Error while starting VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot start VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_suspend(self, name):
        logger.debug('VM suspend %s', name)
        try:
            self.hypervisor.domains[name].suspend()
        except libvirt.libvirtError:
            logger.exception('Error while suspending VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot suspend VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)

    def vm_resume(self, name):
        logger.debug('VM resume %s', name)
        try:
            self.hypervisor.domains[name].resume()
        except libvirt.libvirtError:
            logger.exception('Error while resuming VM %s', name)
            raise
        except KeyError:
            msg = 'Cannot resume VM %s because it is not defined' % name
            logger.error(msg)
            raise UndefinedDomain(msg)


class Hypervisor(object):
    """Container for all hypervisor related state."""
    def __init__(self, name, handler):
        """
        :param str name: name of hypervisor instance
        :param Handler handler: hypervisor handler
        """
        self.handler = weakref.proxy(handler)

        #: hv attributes
        self.name = name
        self.type = u'kvm'

        # register libvirt error handler
        libvirt.registerErrorHandler(self.vir_error_cb, None)
        # libvirt event loop abstraction
        self.vir_event_loop = VirEventLoop(self.handler.main.evloop)
        # This tells libvirt what event loop implementation it
        # should use
        libvirt.virEventRegisterImpl(
            self.vir_event_loop.add_handle,
            self.vir_event_loop.update_handle,
            self.vir_event_loop.remove_handle,
            self.vir_event_loop.add_timer,
            self.vir_event_loop.update_timer,
            self.vir_event_loop.remove_timer,
        )

        self.vir_con = libvirt.open('qemu:///system')  # currently only support KVM

        # findout storage
        self.storage = StorageIndex(self.vir_con)

        logger.debug('Storages: %s', self.storage.paths)

        #: domains: vms, containers...
        self.domains = dict()
        # find defined domains
        for dom_name in self.vir_con.listDefinedDomains():
            dom = self.vir_con.lookupByName(dom_name)
            self.domains[dom.name()] = VirtualMachine(dom, self)
        # find started domains
        for dom_id in self.vir_con.listDomainsID():
            dom = self.vir_con.lookupByID(dom_id)
            self.domains[dom.name()] = VirtualMachine(dom, self)

        logger.debug('Domains: %s', self.domains)

        self.vir_con.domainEventRegister(self.vir_cb, None)  # TODO find out args

    def stop(self):
        self.vir_event_loop.stop()
        # unregister callback
        try:
            self.vir_con.domainEventDeregister(self.vir_cb)
        except libvirt.libvirtError:
            # in case the libvirt connection is broken, it will raise the error
            pass
        ret = self.vir_con.close()
        logger.debug('Libvirt still handling %s ref connections', ret)
        # TODO delet objects

    def vir_error_cb(self, ctxt, err):
        """Libvirt error callback.

        See http://libvirt.org/errors.html for more informations.

        :param ctxt: arbitrary context data (not needed because context is
            givent by self
        :param err: libvirt error code
        """
        logger.error('Libvirt error %s', err)

    def vir_cb(self, conn, dom, event, detail, opaque):
        """Callback for libvirt event loop."""
        logger.debug('Received event %s on domain %s, detail %s', event,
                     dom.name(), detail)

        event = EVENTS[event]

        if event == 'Added':
            vm = VirtualMachine(dom, self)
            logger.info('Created domain %s', vm.name)
            self.domains[vm.name] = vm
            self.handler.tag_db.add_sub_object(vm.name, vm.tags.itervalues())
        elif event == 'Removed':
            vm = self.domains.pop(dom.name())
            logger.info('Removed domain %s', vm.name)
            self.handler.tag_db.remove_sub_object(vm.name)
        elif event in ('Started', 'Suspended', 'Resumed', 'Stopped', 'Saved',
                       'Restored'):
            vm = self.domains.get(dom.name())
            # sometimes libvirt sent a start event before a created event so be
            # careful
            if vm is not None:
                state = DOMAIN_STATES[dom.info()[0]]
                logger.info('Domain change state from %s to %s', vm.state,
                             state)
                vm.state = state

        # update domain state counts
        for tag in ('nvm', 'vmpaused', 'vmstarted', 'vmstopped'):
            # TODO tag announcement
            self.handler.tag_db['__main__'][tag].calculate_value()

    def vm_define(self, xml_desc):
        """Create a VM on the Hypervisor
        :param str xml_desc: XML description in libvirt format
        :return: VM name created
        """
        try:
            return self.vir_con.defineXML(xml_desc).name()
        except libvirt.libvirtError:
            logger.exception('Error while creating domain')
            # reraise exception for the cc-server
            raise

    def _count_domain(self, filter=lambda d: True):
        count = 0

        for dom in self.domains.itervalues():
            if filter(dom):
                count += 1

        return count

    @property
    def vm_started(self):
        """Number of VMs started."""
        return self._count_domain(lambda d: d.state == 'running')

    @property
    def vm_stopped(self):
        """Number of VMs stopped."""
        return self._count_domain(lambda d: d.state == 'stopped')

    @property
    def vm_paused(self):
        """Number of VMs paused."""
        return self._count_domain(lambda d: d.state == 'paused')

    @property
    def vm_total(self):
        """Total number of VMs on the hypervisor."""
        return self._count_domain()


class StorageIndex(object):
    """Keep an index of all storage volume paths."""
    def __init__(self, lv_con):
        """
        :param lv_con: Libvirt connection
        """
        self.storages = dict(
            (s.name, s) for s in imap(
                Storage,
                imap(
                    lv_con.storagePoolLookupByName,
                    chain(
                        lv_con.listDefinedStoragePools(),
                        lv_con.listStoragePools(),
                    ),
                ),
            ),
        )

        self.paths = dict(
            (v.path, v) for v in chain.from_iterable(map(
                lambda s: s.volumes,
                self.storages.itervalues(),
            )),
        )

    def get_volume(self, path):
        return self.paths.get(path)

    def get_storage(self, name):
        return self.Storage.get(name)


class Storage(object):
    """Storage abstraction."""
    def __init__(self, lv_storage):
        """
        :param lv_storage: Libvirt pool storage instance
        """
        self.uuid = lv_storage.UUID()
        self.name = lv_storage.name()

        self.state, self.capacity, self.allocation, self.available = lv_storage.info()
        self.state = STORAGE_STATES[self.state]

        self.volumes = map(
            Volume,
            (lv_storage.storageVolLookupByName(n) for n in
            lv_storage.listVolumes()),
        )


class Volume(object):
    """Volume abstraction."""
    def __init__(self, lv_volume):
        """
        :param lv_volume: Libvirt volume instance
        """
        self.storage = lv_volume.storagePoolLookupByVolume().name()
        self.path = lv_volume.path()
        self.name = lv_volume.name()
        self.capacity, self.allocation = lv_volume.info()[1:]