Tag Archives: Python

Reseting, restarting or rebooting virtual machine

May 30, 2012 23:15 ⋅ Leave a Comment ⋅ Łukasz Oleś

Libvirt gives you a several ways to reboot virtual machine:

reboot – by default it sends ACPI request to VM. It can be ignored(acpid daemon required in vm)
reset – emulates the power reset button on a machine
send ctrl-alt-del keys

Some examples in python:
Reboot

import libvirt

conn = libvirt.open("qemu:///system")
dom = conn.lookupByName('test_vm')
dom.reboot(0)

import libvirt

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName('test_vm')

dom.reboot(0)

Reset:

import libvirt

conn = libvirt.open("qemu:///system")
dom = conn.lookupByName('test_vm')
dom.reset(0)

import libvirt

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName('test_vm')

dom.reset(0)

Send ctrl-alt-del:

import libvirt

conn = libvirt.open("qemu:///system")
dom = conn.lookupByName('test_vm')
#29 - LEFT_CTRL, 56 - LEFT_ALT, 111 - DELETE
dom.sendKey(0, 0, [29, 56, 111], 3, 0)

import libvirt

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName('test_vm')

#29 - LEFT_CTRL, 56 - LEFT_ALT, 111 - DELETE

dom.sendKey(0, 0, [29, 56, 111], 3, 0)

Posted in: Virtualization ⋅ Tagged: libvirt, python

Get network stats for virtual machine

May 23, 2012 16:29 ⋅ Leave a Comment ⋅ Łukasz Oleś

from xml.etree import ElementTree as ET

import libvirt

def dom_network_stats(name):
    stats = {}
    conn = libvirt.open("qemu:///system")
    dom = conn.lookupByName(name)
    xe = ET.fromstring(dom.XMLDesc(0))
    for iface in xe.findall('.//devices/interface'):
        mac = iface.find('mac').get('address')
        iface_name = iface.find('target').get('dev')
        rx, _, _, _, tx, _, _, _ = dom.interfaceStats(iface_name)
        stats[mac] = {'rx' : rx, 'tx' : tx}
    return stats

from xml.etree import ElementTree as ET

import libvirt

def dom_network_stats(name):

stats = {}

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName(name)

xe = ET.fromstring(dom.XMLDesc(0))

for iface in xe.findall('.//devices/interface'):

mac = iface.find('mac').get('address')

iface_name = iface.find('target').get('dev')

rx, _, _, _, tx, _, _, _ = dom.interfaceStats(iface_name)

stats[mac] = {'rx' : rx, 'tx' : tx}

return stats

It retunrs values in bytes.

Read more about interfaceStats in libvirt C API docs.

Posted in: Virtualization ⋅ Tagged: libvirt, network, python

Getting disk space usage from running VM.

May 16, 2012 18:11 ⋅ 1 Comment ⋅ Łukasz Oleś

There is amazing tool which may help in many administrative tasks. It is called libguestfs. To get information about disk space usage you can use program virt-df.
To get disks stats from all running vms just run(libvirt required):

virt-df

virt-df

To get disks stats from specific vm:

virt-df -d <vm_name>

1	virt-df -d <vm_name>

If you do not have libvirt, you can manually specify disk

virt-df -a <path_to_disk>

1	virt-df -a <path_to_disk>

Libguestfs is mainly written in C, but it provides bindings for other languages : C++, Erlang, Java, OCaml, Perl, Python, Ruby.
For example to get disk stats in python you can use this code:

from xml.etree import ElementTree as ET

import guestfs
import libvirt

def df(name):
    stats = {}
    g = guestfs.GuestFS()
    c = libvirt.open('qemu:///system')
    dom = c.lookupByName(name)
    dom_info = ET.fromstring(dom.XMLDesc(0))
    disks = xml_disks = dom_info.findall('.//disk')
    for disk in disks:
        disk_path = disk.find('source').get('file')
        g.add_drive_opts(disk_path, format='raw', readonly=1)
    g.launch()
    file_systems = g.list_filesystems()
    for fs in file_systems:
       if fs[1] not in ['', 'swap', 'unknown']:
           g.mount(fs[0], '/')
           stats[fs[0]] = g.statvfs('/')
           g.umount_all()
    g.close()
    return stats

if __name__ == '__main__':
    print df('vm_name')

from xml.etree import ElementTree as ET

import guestfs

import libvirt

def df(name):

stats = {}

g = guestfs.GuestFS()

c = libvirt.open('qemu:///system')

dom = c.lookupByName(name)

dom_info = ET.fromstring(dom.XMLDesc(0))

disks = xml_disks = dom_info.findall('.//disk')

for disk in disks:

disk_path = disk.find('source').get('file')

g.add_drive_opts(disk_path, format='raw', readonly=1)

g.launch()

file_systems = g.list_filesystems()

for fs in file_systems:

if fs[1] not in ['', 'swap', 'unknown']:

g.mount(fs[0], '/')

stats[fs[0]] = g.statvfs('/')

g.umount_all()

g.close()

return stats

if __name__ == '__main__':

print df('vm_name')

Posted in: Virtualization ⋅ Tagged: libguestfs, libvirt, python

Attaching disk via libvirt using python

May 9, 2012 08:00 ⋅ 4 Comments ⋅ Łukasz Oleś

from xml.etree import ElementTree as ET

import libvirt

DISK_TEMPLATE = \
'''<disk type="file" device="disk">
        <driver name="qemu" type="raw" />
        <source file="{path}"/>
        <target bus='virtio' dev="{dev}"/>
</disk>
'''

def attach_disk(domain, path, dev):
    conn = libvirt.open("qemu:///system")
    dom = conn.lookupByName(domain)
    template = DISK_TEMPLATE.format(path=path, dev=dev)
    dom.attachDevice(template)

attach_disk('vm1', '/mnt/big.img', 'vdb')

from xml.etree import ElementTree as ET

import libvirt

DISK_TEMPLATE = \

'''<disk type="file" device="disk">

</disk>

'''

def attach_disk(domain, path, dev):

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName(domain)

template = DISK_TEMPLATE.format(path=path, dev=dev)

dom.attachDevice(template)

attach_disk('vm1', '/mnt/big.img', 'vdb')

In VM load modules acpiphp, pci_hotplug. Read more on KVM site

Posted in: Virtualization ⋅ Tagged: libvirt, python, qemu, tips

Changing qemu VNC password via libvirt using python

May 8, 2012 22:47 ⋅ 3 Comments ⋅ Łukasz Oleś

from xml.etree import ElementTree as ET

import libvirt

def set_vnc_passwd(domain, passwd):
    conn = libvirt.open("qemu:///system")
    dom = conn.lookupByName(domain)
    xml = ET.fromstring(dom.XMLDesc(0))
    graphic_element = xml.find('.//graphics')
    graphic_element.attrib['passwd'] = passwd
    dom.updateDeviceFlags(ET.tostring(graphic_element), 0)

from xml.etree import ElementTree as ET

import libvirt

def set_vnc_passwd(domain, passwd):

conn = libvirt.open("qemu:///system")

dom = conn.lookupByName(domain)

xml = ET.fromstring(dom.XMLDesc(0))

graphic_element = xml.find('.//graphics')

graphic_element.attrib['passwd'] = passwd

dom.updateDeviceFlags(ET.tostring(graphic_element), 0)

Posted in: Virtualization ⋅ Tagged: libvirt, python, qemu, tips

Tag Archives: Python

Reseting, restarting or rebooting virtual machine

Get network stats for virtual machine

Getting disk space usage from running VM.

Attaching disk via libvirt using python

Changing qemu VNC password via libvirt using python

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