vm-resolver

#! /usr/bin/env python

import glob
import json

DNSMASQ_PATH = '/var/lib/libvirt/dnsmasq/*.status'
HOSTS_PATH = '/etc/hosts'
COMMENT = '# libvirt instances\n'

vms = []

for f in glob.glob(DNSMASQ_PATH):
    with open(f) as st_file:
        data = json.load(st_file)
        for vm in data:
            if 'hostname' in vm:
                vms.append((vm['ip-address'], vm['hostname']))

updated = False

hosts = []

with open(HOSTS_PATH, 'r') as f:
    for line in f.readlines():
        hosts.append(line)
        if 'libvirt instances' in line:
            updated = True
            break


if not updated:
    hosts.append('\n\n')
    hosts.append(COMMENT)

for vm in vms:
    hosts.append('{}\t{}\n'.format(vm[0], vm[1]))

with open(HOSTS_PATH, 'w') as f:
    f.writelines(hosts)