libvirt dynamic inventory

README.md

This asumes that your VM's in your libvirt network, have functioning DNS, using dnsmasq provided by libvirt and your host.

libvirt-inventory.py

#!/usr/bin/env python

import libvirt, json
from sys import stderr, argv
from xml.dom import minidom

### Default (Globals)
# We want this to run on the local system only.
host_domain = 'qemu:///system'

# Initialize the dictionary.  May be a horrible way to deal with it, but deal with it.
inventory = {}
inventory['_meta'] = {}
inventory['_meta']['hostvars'] = {}
inventory['all'] = {}
inventory['all']['children'] = ['active', 'inactive']
inventory['active'] = {}
inventory['inactive'] = {}


def get_doms_network(dom_list):
    dom_networks = []
    for dom in dom_list:
        raw_xml = dom.XMLDesc(0)
        xml = minidom.parseString(raw_xml)

        interfaceTypes = xml.getElementsByTagName('interface')
        for interfaceType in interfaceTypes:
            interfaceNodes = interfaceType.childNodes

            for interfaceNode in interfaceNodes:
                if interfaceNode.nodeName[0:1] != "#":
                    try:
                        dom_networks.append({'domain': dom.name(),
                            'network': interfaceNode.attributes['network'].value})
                    except:
                        # the interfaceNode, does not have the attribute 'network'
                        # hasattr(interfaceNode, 'network')
                        # gennerally this can be ignored, thus pass.
                        pass

    return dom_networks


def get_dom_domain(network_name):
    raw_xml = virthost.networkLookupByName(network_name).XMLDesc(0)
    xml = minidom.parseString(raw_xml)

    return xml.getElementsByTagName('domain')[0].getAttribute('name')


def populate_inventory():
    if virthost == None:
        print('Failed to open connection to {}'.format(host_domain), file=stderr)
        exit(1)

    activedomains = virthost.listAllDomains(libvirt.VIR_CONNECT_LIST_DOMAINS_ACTIVE)
    inactivedomains = virthost.listAllDomains(libvirt.VIR_CONNECT_LIST_DOMAINS_INACTIVE)

    for dom_list in [(activedomains, 'active'), (inactivedomains, 'inactive')]:
        host_list = []
        for d in get_doms_network(dom_list[0]):
            host_list.append("{}.{}".format(d['domain'], get_dom_domain(d['network'])))

        if host_list:
            inventory[dom_list[1]]['hosts'] = host_list
            inventory[dom_list[1]]['vars'] = {}


if __name__ == '__main__':
    if len(argv) == 2 and argv[1] == '--list':
        virthost = libvirt.open(host_domain)
        populate_inventory()
        virthost.close()

        print(json.dumps(inventory, indent=4, sort_keys=True))

    elif len(argv) == 3 and argv[1] == '--host':
        # 1: Host var's are 'empty'; from this script
        # 2: We don't do anything to set these!
        #   TODO: Look a pulling this from domain metadata?
        #   - https://libvirt.org/formatdomain.html#elementsMetadata
        # 3: Ansible docs say return an empty dict '{}'
        #   - https://docs.ansible.com/ansible/latest/dev_guide/developing_inventory.html
        print(json.dumps({}))

    else:
        print("Need an argument, either --list or --host <host>", file=stderr)
        exit(1)