On Fri, Apr 11, 2014 at 1:23 PM, Daniel P. Berrange <berrange@redhat.com> wrote:
On Fri, Apr 11, 2014 at 01:14:50PM +0200, Ruben Kerkhof wrote:
Hi all,
I have a few python scripts which use the libvirt api to get interface and block device statistics. What has been bugging me for a while now that is that there’s no high level api to get a list of all interfaces or block devices for a vm. The list can be retrieved from the xml with a bit of Xpath magic, but this seems to me to break the nice abstraction layer libvirt provides. Ideally, I don’t have to do anything with xml, and add dependencies on xml parsers to my code.
I’ve seen examples of code doing this, for example the collectd libvirt plugin, but there must be many others.
Can I kindly ask for such an API? Unfortunately I don’t have the skills to code this up myself.
The libvirt-glib project provides a set of libraries including libvirt-gconfig which intend to fill the gap you describe. They are accessible from Python using GObject Introspection support. The goal of libvirt-gconfig is to remove the need for apps to know anything about XML at all.
So now instead of having to learn XML parsing I'll have to learn GObject and glib? And instead of a dependency on an xml parser I'll have to add one on glib. Not exactly the easy solution I was hoping for ;-) I still think that a method to get the interfaces for a vm is a gap in the current api, which is working fine for all my other needs. I can get the interfaces for a node, so why not for a vm?
eg,this demo program shows how to build a domain config using the APIs. For parsing you just pass it the XML document and then can use the various getters to access info
#!/usr/bin/python
from gi.repository import LibvirtGConfig;
domain = LibvirtGConfig.Domain.new() domain.set_virt_type(LibvirtGConfig.DomainVirtType.KVM) domain.set_name("foo") domain.set_memory(1024*1024) # 1 GB domain.set_vcpus(2) domain.set_lifecycle(LibvirtGConfig.DomainLifecycleEvent.ON_POWEROFF, LibvirtGConfig.DomainLifecycleAction.DESTROY) domain.set_virt_type(LibvirtGConfig.DomainVirtType.KVM)
clock = LibvirtGConfig.DomainClock.new() clock.set_offset(LibvirtGConfig.DomainClockOffset.UTC) domain.set_clock(clock)
os = LibvirtGConfig.DomainOs.new() os.set_os_type(LibvirtGConfig.DomainOsType.HVM) os.set_arch("x86_64") devices = [ LibvirtGConfig.DomainOsBootDevice.CDROM, LibvirtGConfig.DomainOsBootDevice.NETWORK ] os.set_boot_devices(devices) domain.set_os(os)
disk = LibvirtGConfig.DomainDisk.new() disk.set_type(LibvirtGConfig.DomainDiskType.FILE) disk.set_guest_device_type(LibvirtGConfig.DomainDiskGuestDeviceType.DISK) disk.set_source("/tmp/foo/bar") disk.set_driver_name("qemu") disk.set_driver_format(LibvirtGConfig.DomainDiskFormat.QCOW2) disk.set_target_bus(LibvirtGConfig.DomainDiskBus.IDE) disk.set_target_dev("hda") domain.add_device(disk)
interface = LibvirtGConfig.DomainInterfaceNetwork.new() interface.set_source("default") filterref = LibvirtGConfig.DomainInterfaceFilterref.new() filterref.set_name("clean-traffic") parameter = LibvirtGConfig.DomainInterfaceFilterrefParameter.new() parameter.set_name("IP") parameter.set_value("205.23.12.40") filterref.add_parameter(parameter) interface.set_filterref(filterref) domain.add_device(interface)
interface = LibvirtGConfig.DomainInterfaceUser.new() interface.set_ifname("eth0") interface.set_link_state(LibvirtGConfig.DomainInterfaceLinkState.UP) interface.set_mac("00:11:22:33:44:55") interface.set_model("foo") domain.add_device(interface)
input = LibvirtGConfig.DomainInput.new() input.set_device_type(LibvirtGConfig.DomainInputDeviceType.TABLET) input.set_bus(LibvirtGConfig.DomainInputBus.USB) domain.add_device(input)
graphics = LibvirtGConfig.DomainGraphicsSpice.new() graphics.set_port(1234) domain.add_device(graphics)
video = LibvirtGConfig.DomainVideo.new() video.set_model(LibvirtGConfig.DomainVideoModel.QXL) domain.add_device(video)
console = LibvirtGConfig.DomainConsole.new() pty = LibvirtGConfig.DomainChardevSourcePty.new() console.set_source(pty) domain.add_device(console)
print domain.to_xml()
pool = LibvirtGConfig.StoragePool.new() pool.set_pool_type(LibvirtGConfig.StoragePoolType.DIR)
pool_source = LibvirtGConfig.StoragePoolSource.new() pool_source.set_directory("/foo/bar") pool.set_source(pool_source)
perms = LibvirtGConfig.StoragePermissions.new() perms.set_owner(1001) perms.set_group(1005) perms.set_mode(0744) perms.set_label("virt_image_t")
pool_target = LibvirtGConfig.StoragePoolTarget.new() pool_target.set_path("/dev/disk/by-path") pool_target.set_permissions(perms) pool.set_target(pool_target)
print pool.to_xml()
vol = LibvirtGConfig.StorageVol.new() vol.set_name("my-vol") vol.set_capacity(0xdeadbeef)
vol_target = LibvirtGConfig.StorageVolTarget.new() vol_target.set_format("qcow2") vol_target.set_permissions(perms) vol.set_target(vol_target)
print vol.to_xml()
Thanks for the example, I'll dig into it. I just read https://www.berrange.com/posts/2011/11/22/introducing-the-libvirt-glib-a-map... Is there any documentation available for libvirt-gobject online? Unfortunately I'm still stuck on Scientific Linux 6.5 There are no packages for libvirt-glib in the Scientific Linux repo, are they available for libvirt 0.10 on RHEL 6.5?
Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
Kind regards, Ruben