Very simple OpenStack Nova notifier to create/delete PowerDNS records for instances on creation/deletion.

examplenotifier.py

'''
Very simple OpenStack Nova notifier to create/delete PowerDNS records for instances on creation/deletion.

Format of records is %(instance)s.%(project_name).example.com.

To use:
* Install this in a python path (site-packages is easiest)
* Configure nova using notification_driver=examplenotifier
'''
import MySQLdb
import sys
from nova import db
from nova import notifications
from nova.openstack.common import log as logging
from nova.openstack.common.notifier import api as notifier_api

log = logging.getLogger(__name__)
instance_zone = 'example.com'

def notify(context, message):
    event_type = message['event_type']
    if event_type not in ['compute.instance.delete.start',
                            'compute.instance.create.end',
                            'compute.instance.create_ip.end',
                            'compute.instance.delete_ip.end']:
        return

    payload = message['payload']
    instance_name = payload['display_name']
    uuid = payload['instance_id']
    tenant_id = payload['tenant_id']
    project_name = context.project_name
    dns = '%s.%s.%s' % (instance_name.lower(), project_name.lower(), instance_zone)

    db = MySQLdb.connect(host='mysql.example.com', user='pdns',
                            passwd='password', db='pdns')
    cursor = db.cursor()

    if event_type in ['compute.instance.create.end', 'compute.instance.create_ip.end']:
        if not 'fixed_ips' in payload or len(payload['fixed_ips']) == 0:
            log.error('No IPs found for %s', instance_name)
            return
        ip = payload['fixed_ips'][0]['address']
        rev_ip_parts = ip.split('.')
        rev_ip_parts.reverse()
        ptr = "%s.in-addr.arpa" % '.'.join(rev_ip_parts)
        ptr_zone = "%s.in-addr.arpa" % '.'.join(rev_ip_parts[1:])

        log.info('Creating A record %s with ip %s' % (dns, ip))
        cursor.execute('INSERT INTO `records` (domain_id, name, type, content) VALUES ((SELECT `id` FROM `domains` WHERE `name` = %(zone)s LIMIT 0,1), %(dns)s, "A", %(ip)s)', {'dns': dns, 'ip': ip, 'zone': instance_zone})
        db.commit()

        log.info('Creating PTR record %s (%s) with name %s' % (ptr, ptr_zone, dns))
        cursor.execute('INSERT INTO `records` (domain_id, name, type, content) VALUES ((SELECT `id` FROM `domains` WHERE `name` = %(zone)s LIMIT 0,1), %(ptr)s, "PTR", %(name)s)', {'ptr': ptr, 'zone': ptr_zone, 'name': dns})
        db.commit()

    if event_type in ['compute.instance.delete_ip.end', 'compute.instance.delete.start']:
        log.info('Deleting A records for %s' % dns)
        cursor.execute('DELETE `records` FROM `records` LEFT JOIN `domains` on `records`.`domain_id` = `domains`.`id` WHERE `records`.`name` = %(dns)s AND `records`.`type` = "A" AND `domains`.`name` = %(zone)s', {'dns': dns, 'zone': instance_zone})
        db.commit()

        log.info('Deleting PTR records for %s' % dns)
        cursor.execute('DELETE FROM `records` WHERE `records`.`content` = %(dns)s AND `records`.`type` = "PTR"', {'dns': dns})
        db.commit()

    cursor.close()
    db.close()