135 lines
4.1 KiB
Python
135 lines
4.1 KiB
Python
#!/usr/bin/env python
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Command-line utility to get the IP address from the newest DHCP lease.
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It's written for using with vagrant-hostmanager and vagrant-libvirt plugins.
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Vagrant-hostmanager by default fetches only IP addresses from eth0 interfaces
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on VM-s. Therefore, the first purpose of this utility is to be able to fetch
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the address also from the other interfaces.
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Libvirt/virsh only lists all DHCP leases for the given network with timestamps.
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DHCP leases have their expiration time, but are not cleaned up after destroying
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VM. If someone destroys and sets up the VM with the same hostname, we have
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many DHCP leases for the same hostname and we have to look up for timestamp.
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That's the second purpose of this script.
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"""
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import argparse
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import csv
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import functools
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import operator
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import xml.etree.ElementTree as etree
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import libvirt
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class NoPrivateDHCPInterfaceException(Exception):
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pass
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class NoDHCPLeaseException(Exception):
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pass
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def libvirt_conn(f):
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@functools.wraps(f)
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def wrapper(*args, **kwargs):
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conn = libvirt.openReadOnly('qemu:///system')
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return f(conn, *args, **kwargs)
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return wrapper
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@libvirt_conn
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def get_vir_network_dhcp_lease(conn, vm_name):
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"""Libvirt since 1.2.6 version provides DHCPLeases method in virNetwork.
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That's the current official way for getting DHCP leases and this
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information isn't stored anywhere else anymore.
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"""
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domain_name = 'vagrant_' + vm_name
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mac_address = get_mac_address(conn, domain_name)
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network = conn.networkLookupByName('vagrant-private-dhcp')
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dhcp_leases = libvirt.virNetwork.DHCPLeases(network)
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vm_dhcp_leases = filter(lambda lease: lease['mac'] == mac_address,
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dhcp_leases)
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newest_vm_dhcp_lease = sorted(vm_dhcp_leases,
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key=operator.itemgetter('expirytime'),
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reverse=True)[0]['ipaddr']
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return newest_vm_dhcp_lease
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def get_mac_address(conn, domain_name):
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"""Get MAC address from domain XML."""
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domain = conn.lookupByName(domain_name)
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domain_xml = domain.XMLDesc()
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domain_tree = etree.fromstring(domain_xml)
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devices = domain_tree.find('devices')
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interfaces = devices.iterfind('interface')
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for interface in interfaces:
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source = interface.find('source')
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if source is None or source.get('network') != 'vagrant-private-dhcp':
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continue
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mac_element = interface.find('mac')
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mac_address = mac_element.get('address')
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return mac_address
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raise NoPrivateDHCPInterfaceException()
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@libvirt_conn
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def get_dnsmasq_dhcp_lease(conn, vm_name):
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"""In libvirt under 1.2.6 DHCP leases are stored in file.
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There is no API for DHCP leases yet.
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"""
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domain_name = 'vagrant_' + vm_name
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mac_address = get_mac_address(conn, domain_name)
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with open(
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'/var/lib/libvirt/dnsmasq/vagrant-private-dhcp.leases'
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) as leases_file:
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reader = csv.reader(leases_file, delimiter=' ')
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for row in reader:
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lease_mac, lease_ip, lease_vm_name = row[1:4]
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if not (lease_mac == mac_address and lease_vm_name == vm_name):
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continue
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return lease_ip
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raise NoDHCPLeaseException()
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def main():
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parser = argparse.ArgumentParser()
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parser.add_argument('vm_name', help='Name of the virtual machine')
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args = parser.parse_args()
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vm_name = args.vm_name
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if libvirt.getVersion() >= 1002006:
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newest_dhcp_lease = get_vir_network_dhcp_lease(vm_name)
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else:
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newest_dhcp_lease = get_dnsmasq_dhcp_lease(vm_name)
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print(newest_dhcp_lease)
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if __name__ == '__main__':
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main()
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