Hi Cole, On Fri, Apr 11, 2014 at 2:50 PM, Cole Robinson <crobinso@redhat.com> wrote:
On 04/11/2014 07:14 AM, 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.
It's an unavoidable fact that XML is part of the libvirt API. Going down the route of providing APIs that return bits and pieces of the XML is a slippery slope and increases libvirt maintenance burden.
python has a native XML library. To do what you want is pretty straight forward once you understand the concepts. For example this prints every interface mac address for the VM 'f20':
import xml.etree.ElementTree as ET import libvirt
conn = libvirt.open("qemu:///system") dom = conn.lookupByName("f20") xml = dom.XMLDesc(0)
root = ET.fromstring(xml) ifaces = root.findall("./devices/interface/mac") for iface in ifaces: print iface.attrib["address"]
You're right, it's not that hard. I've been using something like the following code for a while now: def get_interfaces(dom): interfaces = {} tree = ElementTree.fromstring(dom.XMLDesc(0)) for interface in tree.findall("devices/interface"): target = interface.find("target") if target is None: continue dev = target.get("dev") mac = interface.find("mac").get("address") if not dev in interfaces: interfaces[dev] = mac return interfaces Kind regards, Ruben