vm_tags.py

import logging
from functools import wraps
from xml.etree import cElementTree as et
from StringIO import StringIO

import libvirt

from ccnode.tags import ttl, refresh


logger = logging.getLogger(__name__)


def _vir_tag(func):
    """Catches libvirt related exception.

    Decorator used for tag declarations that interacts with libvirt.

    """
    @wraps(func)
    def decorated(dom):
        if not dom.hypervisor.handler.virt_connected:
            return
        try:
            func(dom)
        except libvirt.libvirtError:
            logger.exception('Unexpected libvirt error')
            dom.hypervisor.handler.virt_connect_restart()

    return decorated


def uuid(dom):
    """Unique identifier of the domain."""
    return dom.uuid


@ttl(5)
def status(dom):
    return dom.state


def hv(dom):
    #FIXME: what shoud be the value of this tag ?
    return dom.hypervisor.name


def htype(dom):
    return dom.hypervisor.type


@_vir_tag
def arch(dom):
    """VM CPU architecture."""
    try:
        return dict(i686='x86', x86_64='x64')[et.ElementTree().parse(
            StringIO(dom.lv_dom.XMLDesc(0))).find('os/type').get('arch')]
    except Exception:
        logger.exception('Error while get Architecture tag')


def h(dom):
    """Name of the VM."""
    return dom.name


@_vir_tag
def cpu(dom):
    """Number of CPU of the VM."""
    return dom.lv_dom.info()[3]


@ttl(10)
@refresh(5)
def cpuuse():
    pass


@_vir_tag
def mem(dom):
    """Memory currently allocated."""
    return dom.lv_dom.info()[2] * 1024


@_vir_tag
def memmax(dom):
    """Maximum memory allocation."""
    return dom.lv_dom.info()[1] * 1024


@_vir_tag
def vncport(dom):
    """VNC port for the VM console access."""
    try:
        return et.ElementTree().parse(
            StringIO(dom.lv_dom.XMLDesc(0))
        ).find('devices/graphics').get('port')
    except Exception:
        logger.exception('VNCPort')


@ttl(10)
@refresh(10)
@_vir_tag
def disk(dom):
    """Get backend disks."""
    return u' '.join(map(str, xrange(len(dom.disks)))) or None


@ttl(10)
@refresh(10)
@_vir_tag
def nic(dom):
    """VM network interfaces."""
    return u' '.join(map(str, xrange(len(dom.nics)))) or None