models.py

# -*- coding: utf-8 -*-

# Copyright 2014 Budapest University of Technology and Economics (BME IK)
#
# This file is part of CIRCLE Cloud.
#
# CIRCLE is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# CIRCLE is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along
# with CIRCLE.  If not, see <http://www.gnu.org/licenses/>.

from __future__ import unicode_literals

import logging
from os.path import join
import uuid

from celery.contrib.abortable import AbortableAsyncResult
from django.db.models import (Model, BooleanField, CharField, DateTimeField,
                              ForeignKey)
from django.utils import timezone
from django.utils.translation import ugettext_lazy as _
from model_utils.models import TimeStampedModel
from sizefield.models import FileSizeField

from .tasks import local_tasks, storage_tasks
from celery.exceptions import TimeoutError
from common.models import WorkerNotFound

logger = logging.getLogger(__name__)


class DataStore(Model):

    """Collection of virtual disks.
    """
    name = CharField(max_length=100, unique=True, verbose_name=_('name'))
    path = CharField(max_length=200, unique=True, verbose_name=_('path'))
    hostname = CharField(max_length=40, unique=True,
                         verbose_name=_('hostname'))

    class Meta:
        ordering = ['name']
        verbose_name = _('datastore')
        verbose_name_plural = _('datastores')

    def __unicode__(self):
        return u'%s (%s)' % (self.name, self.path)

    def get_remote_queue_name(self, queue_id, priority=None,
                              check_worker=True):
        logger.debug("Checking for storage queue %s.%s",
                     self.hostname, queue_id)
        if not check_worker or local_tasks.check_queue(self.hostname,
                                                       queue_id,
                                                       priority):
            queue_name = self.hostname + '.' + queue_id
            if priority is not None:
                queue_name = queue_name + '.' + priority
            return queue_name
        else:
            raise WorkerNotFound()

    def get_deletable_disks(self):
        return [disk.filename for disk in
                self.disk_set.filter(
                    destroyed__isnull=False) if disk.is_deletable]


class Disk(TimeStampedModel):

    """A virtual disk.
    """
    TYPES = [('qcow2-norm', 'qcow2 normal'), ('qcow2-snap', 'qcow2 snapshot'),
             ('iso', 'iso'), ('raw-ro', 'raw read-only'), ('raw-rw', 'raw')]
    name = CharField(blank=True, max_length=100, verbose_name=_("name"))
    filename = CharField(max_length=256, unique=True,
                         verbose_name=_("filename"))
    datastore = ForeignKey(DataStore, verbose_name=_("datastore"),
                           help_text=_("The datastore that holds the disk."))
    type = CharField(max_length=10, choices=TYPES)
    size = FileSizeField(null=True, default=None)
    base = ForeignKey('self', blank=True, null=True,
                      related_name='derivatives')
    dev_num = CharField(default='a', max_length=1,
                        verbose_name=_("device number"))
    destroyed = DateTimeField(blank=True, default=None, null=True)

    is_ready = BooleanField(default=False)

    class Meta:
        ordering = ['name']
        verbose_name = _('disk')
        verbose_name_plural = _('disks')
        permissions = (
            ('create_empty_disk', _('Can create an empty disk.')),
            ('download_disk', _('Can download a disk.')))

    class WrongDiskTypeError(Exception):

        def __init__(self, type, message=None):
            if message is None:
                message = ("Operation can't be invoked on a disk of type '%s'."
                           % type)

            Exception.__init__(self, message)

            self.type = type

    class DiskInUseError(Exception):

        def __init__(self, disk, message=None):
            if message is None:
                message = ("The requested operation can't be performed on "
                           "disk '%s (%s)' because it is in use." %
                           (disk.name, disk.filename))

            Exception.__init__(self, message)

            self.disk = disk

    class DiskIsNotReady(Exception):

        """ Exception for operations that need a deployed disk.
        """

        def __init__(self, disk, message=None):
            if message is None:
                message = ("The requested operation can't be performed on "
                           "disk '%s (%s)' because it has never been"
                           "deployed." % (disk.name, disk.filename))

            Exception.__init__(self, message)

            self.disk = disk

    @property
    def path(self):
        """The path where the files are stored.
        """
        return join(self.datastore.path, self.filename)

    @property
    def vm_format(self):
        """Returns the proper file format for different type of images.
        """
        return {
            'qcow2-norm': 'qcow2',
            'qcow2-snap': 'qcow2',
            'iso': 'raw',
            'raw-ro': 'raw',
            'raw-rw': 'raw',
        }[self.type]

    @property
    def format(self):
        """Returns the proper file format for different types of images.
        """
        return {
            'qcow2-norm': 'qcow2',
            'qcow2-snap': 'qcow2',
            'iso': 'iso',
            'raw-ro': 'raw',
            'raw-rw': 'raw',
        }[self.type]

    @property
    def device_type(self):
        """Returns the proper device prefix for different types of images.
        """
        return {
            'qcow2-norm': 'vd',
            'qcow2-snap': 'vd',
            'iso': 'sd',
            'raw-ro': 'vd',
            'raw-rw': 'vd',
        }[self.type]

    @property
    def device_bus(self):
        """Returns the proper device prefix for different types of images.
        """
        return {
            'qcow2-norm': 'virtio',
            'qcow2-snap': 'virtio',
            'iso': 'scsi',
            'raw-ro': 'virtio',
            'raw-rw': 'virtio',
        }[self.type]

    @property
    def is_deletable(self):
        """True if the associated file can be deleted.
        """
        # Check if all children and the disk itself is destroyed.
        return (self.destroyed is not None) and self.children_deletable

    @property
    def children_deletable(self):
        """True if all children of the disk are deletable.
        """
        return all(i.is_deletable for i in self.derivatives.all())

    @property
    def is_in_use(self):
        """True if disk is attached to an active VM.

        'In use' means the disk is attached to a VM which is not STOPPED, as
        any other VMs leave the disk in an inconsistent state.
        """
        return any(i.state != 'STOPPED' for i in self.instance_set.all())

    def get_appliance(self):
        """Return the Instance or InstanceTemplate object where the disk
        is used
        """
        from vm.models import Instance
        try:
            return self.instance_set.get()
        except Instance.DoesNotExist:
            return self.template_set.get()

    def get_exclusive(self):
        """Get an instance of the disk for exclusive usage.

        This method manipulates the database only.
        """
        type_mapping = {
            'qcow2-norm': 'qcow2-snap',
            'iso': 'iso',
            'raw-ro': 'raw-rw',
        }

        if self.type not in type_mapping.keys():
            raise self.WrongDiskTypeError(self.type)

        new_type = type_mapping[self.type]

        return Disk.create(base=self, datastore=self.datastore,
                           name=self.name, size=self.size,
                           type=new_type)

    def get_vmdisk_desc(self):
        """Serialize disk object to the vmdriver.
        """
        return {
            'source': self.path,
            'driver_type': self.vm_format,
            'driver_cache': 'none',
            'target_device': self.device_type + self.dev_num,
            'target_bus': self.device_bus,
            'disk_device': 'cdrom' if self.type == 'iso' else 'disk'
        }

    def get_disk_desc(self):
        """Serialize disk object to the storage driver.
        """
        return {
            'name': self.filename,
            'dir': self.datastore.path,
            'format': self.format,
            'size': self.size,
            'base_name': self.base.filename if self.base else None,
            'type': 'snapshot' if self.base else 'normal'
        }

    def get_remote_queue_name(self, queue_id='storage', priority=None,
                              check_worker=True):
        """Returns the proper queue name based on the datastore.
        """
        if self.datastore:
            return self.datastore.get_remote_queue_name(queue_id, priority,
                                                        check_worker)
        else:
            return None

    def __unicode__(self):
        return u"%s (#%d)" % (self.name, self.id or 0)

    def clean(self, *args, **kwargs):
        if (self.size is None or "") and self.base:
            self.size = self.base.size
        super(Disk, self).clean(*args, **kwargs)

    def deploy(self, user=None, task_uuid=None, timeout=15):
        """Reify the disk model on the associated data store.

        :param self: the disk model to reify
        :type self: storage.models.Disk

        :param user: The user who's issuing the command.
        :type user: django.contrib.auth.models.User

        :param task_uuid: The task's UUID, if the command is being executed
                          asynchronously.
        :type task_uuid: str

        :return: True if a new reification of the disk has been created;
                 otherwise, False.
        :rtype: bool
        """
        if self.destroyed:
            self.destroyed = None
            self.save()

        if self.is_ready:
            return True
        if self.base and not self.base.is_ready:
            raise Exception("Base image is not ready.")
        queue_name = self.get_remote_queue_name('storage', priority="fast")
        disk_desc = self.get_disk_desc()
        if self.base is not None:
            storage_tasks.snapshot.apply_async(args=[disk_desc],
                                               queue=queue_name
                                               ).get(timeout=timeout)
        else:
            storage_tasks.create.apply_async(args=[disk_desc],
                                             queue=queue_name
                                             ).get(timeout=timeout)

        self.is_ready = True
        self.save()
        return True

    @classmethod
    def create(cls, user=None, **params):
        disk = cls.__create(user, params)
        disk.clean()
        disk.save()
        logger.debug("Disk created: %s", params)
        return disk

    @classmethod
    def __create(cls, user, params):
        datastore = params.pop('datastore', DataStore.objects.get())
        filename = params.pop('filename', str(uuid.uuid4()))
        disk = cls(filename=filename, datastore=datastore, **params)
        return disk

    @classmethod
    def download(cls, url, task, user=None, **params):
        """Create disk object and download data from url synchronusly.

        :param url: image url to download.
        :type url: url
        :param instance: Instance or template attach the Disk to.
        :type instance: vm.models.Instance or InstanceTemplate or NoneType
        :param user: owner of the disk
        :type user: django.contrib.auth.User
        :param task_uuid: UUID of the local task
        :param abortable_task: UUID of the remote running abortable task.

        :return: The created Disk object
        :rtype: Disk
        """
        params.setdefault('name', url.split('/')[-1])
        params.setdefault('type', 'iso')
        params.setdefault('size', None)
        disk = cls.__create(params=params, user=user)
        queue_name = disk.get_remote_queue_name('storage', priority='slow')
        remote = storage_tasks.download.apply_async(
            kwargs={'url': url, 'parent_id': task.request.id,
                    'disk': disk.get_disk_desc()},
            queue=queue_name)
        while True:
            try:
                result = remote.get(timeout=5)
                break
            except TimeoutError:
                if task is not None and task.is_aborted():
                    AbortableAsyncResult(remote.id).abort()
                    raise Exception("Download aborted by user.")
        disk.size = result['size']
        disk.type = result['type']
        disk.is_ready = True
        disk.save()
        return disk

    def destroy(self, user=None, task_uuid=None):
        if self.destroyed:
            return False

        self.destroyed = timezone.now()
        self.save()
        return True

    def restore(self, user=None, task_uuid=None, timeout=15):
        """Recover destroyed disk from trash if possible.
        """
        queue_name = self.datastore.get_remote_queue_name(
            'storage', priority='slow')
        logger.info("Image: %s at Datastore: %s recovered from trash." %
                    (self.filename, self.datastore.path))
        storage_tasks.recover_from_trash.apply_async(
            args=[self.datastore.path, self.filename],
            queue=queue_name).get(timeout=timeout)

    def save_as(self, task=None, user=None, task_uuid=None, timeout=300):
        """Save VM as template.

        Based on disk type:
        qcow2-norm, qcow2-snap --> qcow2-norm
        iso                    --> iso (with base)

        VM must be in STOPPED state to perform this action.
        The timeout parameter is not used now.
        """
        mapping = {
            'qcow2-snap': ('qcow2-norm', None),
            'qcow2-norm': ('qcow2-norm', None),
            'iso': ("iso", self),
        }
        if self.type not in mapping.keys():
            raise self.WrongDiskTypeError(self.type)

        if self.is_in_use:
            raise self.DiskInUseError(self)

        if not self.is_ready:
            raise self.DiskIsNotReady(self)

        # from this point on, the caller has to guarantee that the disk is not
        # going to be used until the operation is complete

        new_type, new_base = mapping[self.type]

        disk = Disk.create(datastore=self.datastore,
                           base=new_base,
                           name=self.name, size=self.size,
                           type=new_type, dev_num=self.dev_num)

        queue_name = self.get_remote_queue_name("storage", priority="slow")
        remote = storage_tasks.merge.apply_async(kwargs={
            "old_json": self.get_disk_desc(),
            "new_json": disk.get_disk_desc()},
            queue=queue_name
        )  # Timeout
        while True:
            try:
                remote.get(timeout=5)
                break
            except TimeoutError:
                if task is not None and task.is_aborted():
                    AbortableAsyncResult(remote.id).abort()
                    disk.destroy()
                    raise Exception("Save as aborted by use.")
        disk.is_ready = True
        disk.save()
        return disk