Re: [libvirt] API calls to get interfaces and block devices

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.

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()

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 :|