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#!/usr/bin/python
import ConfigParser
import datetime
import os
import logging
from subprocess import check_call
from kombu import Connection, Exchange, Queue
from novaclient.v1_1 import client
CONFIG_FILE = '/etc/serverstack-dns/dns.conf'
logging.basicConfig(level=logging.DEBUG)
def get_config():
config_in = ConfigParser.SafeConfigParser()
if not config_in.read(CONFIG_FILE):
raise Exception('Couldnt load config @ %s.' % CONFIG_FILE)
def _get(setting):
return config_in.get('DEFAULT', setting)
conf = {
'os_username': os.getenv('OS_USERNAME') or _get('os_username'),
'os_password': os.getenv('OS_PASSWORD') or _get('os_password'),
'os_tenant_name': (os.getenv('OS_TENANT_NAME') or
_get('os_tenant_name')),
'os_auth_url': os.getenv('OS_AUTH_URL') or _get('os_auth_url'),
'rabbit_user': _get('rabbit_user'),
'rabbit_password': _get('rabbit_password'),
'rabbit_host': _get('rabbit_host'),
'rabbit_vhost': _get('rabbit_vhost'),
'rabbit_exchange': _get('rabbit_exchange'),
'rabbit_topic': _get('rabbit_topic'),
'include_tenants': _get('include_tenants'),
'hosts_file': _get('hosts_file'),
'domain': _get('domain'),
'upstream_dns': _get('upstream_dns')
}
missing = [k for k in conf.iterkeys() if conf[k] is None]
if missing:
logging.error('Missing config: %s' % missing)
raise Exception('Missing config: %s')
return conf
config = get_config()
def managed_tenants():
with open(config['include_tenants']) as inc:
included = inc.readlines()
return [i.strip() for i in included if not i.startswith('#')]
_client = None
def add_host_entry(hostname, ip, port_id):
hostname = '%s.%s' % (hostname, config['domain'])
entry = '%s %s #port %s' % (ip, hostname, port_id)
with open(config['hosts_file']) as hosts:
hostnames = hosts.readlines()
hostnames = [host.strip() for host in hostnames
if not host.startswith('#')]
out = []
# remove stale entries
for hostname in hostnames:
_hostname = hostname.split(' ')
ip = _hostname[0]
hn = _hostname[1]
p = _hostname[2]
if hn == hostname or p == port_id:
continue
out.append(hostname)
out.append(entry)
with open(config['hosts_file'], 'wb') as cn:
cn.write('# Generated %s\n' % datetime.datetime.utcnow())
cn.write('\n'.join(out))
def remove_host_entry(port_id):
with open(config['hosts_file']) as hosts:
hosts = hosts.readlines()
hosts = [host.strip() for host in hosts if not host.startswith('#')]
out = []
for host in hosts:
if not host.endswith(port_id):
out.append(host)
with open(config['hosts_file'], 'wb') as cn:
cn.write('# Generated %s\n' % datetime.datetime.utcnow())
cn.write('\n'.join(out))
def get_nova_client():
global _client
if _client is not None:
return _client
_client = client.Client(config['os_username'], config['os_password'],
config['os_tenant_name'], config['os_auth_url'],
service_type='compute')
return _client
def get_instance_hostname(instance_id):
client = get_nova_client()
try:
instance = client.servers.get(instance_id)
return instance.name.replace(' ', '-')
except:
logging.error('Could not get server name for instance %s.' %
instance_id)
def manage_dns(body, message):
tenant_ids = [body['_context_tenant_id']]
try:
tenant_ids.append(body['payload']['port']['tenant_id'])
except KeyError:
pass
if not set(managed_tenants()).issubset(set(tenant_ids)):
logging.debug('Skipping event, not managing DNS for tenant %s.' %
tenant_ids)
message.requeue()
return
if body['event_type'] == 'port.create.end':
ip = body['payload']['port']['fixed_ips'][0]['ip_address']
instance_id = body['payload']['port']['device_id']
port_id = body['payload']['port']['id']
hostname = get_instance_hostname(instance_id)
if not hostname:
logging.info('Skipping creation of DNS entry for instance %s.' %
instance_id)
return
logging.info('Creating DNS entry: %s to instance %s with hostname %s.'
% (ip, instance_id, hostname))
add_host_entry(hostname, ip, port_id)
ensure_dnsmasq()
if body['event_type'] == 'port.delete.end':
port_id = body['payload']['port_id']
logging.info('Deleting DNS entry for port %s.' % port_id)
remove_host_entry(port_id)
ensure_dnsmasq()
message.ack()
def process_msg(body, message):
try:
manage_dns(body, message)
except Exception as e:
logging.error('Failed to process notification: %s' % e)
def listen():
nova_x = Exchange(config['rabbit_exchange'], type='topic', durable=False)
info_q = Queue(config['rabbit_topic'], exchange=nova_x, durable=False,
routing_key=config['rabbit_topic'])
conn_url = 'amqp://%s:%s@%s/%s' % (config['rabbit_user'],
config['rabbit_password'],
config['rabbit_host'],
config['rabbit_vhost'])
logging.info('Connecting to rabbit @ %s.' % conn_url)
with Connection(conn_url) as conn:
with conn.Consumer(info_q, callbacks=[process_msg]):
while True:
try:
conn.drain_events()
except KeyboardInterrupt:
break
def ensure_dnsmasq():
pid_file = os.path.join('/var/run/dnsmasq/', config['domain'] + '.pid')
cmd = ['dnsmasq', '--strict-order', '--conf-file=', '--bind-interfaces',
'--domain=%s' % config['domain'], '--no-hosts',
'--addn-hosts=%s' % config['hosts_file'], '-E', '--pid-file=%s' %
pid_file, '-S', config['upstream_dns']]
if os.path.isfile(pid_file):
pid = open(pid_file).read().strip()
proc_cmd = os.path.join('/proc', pid, 'cmdline')
if os.path.isfile(proc_cmd):
logging.info('HUPing running dnsmasq (pid: %s)' % pid)
cmd = ['kill', '-HUP', pid]
check_call(cmd)
return
logging.info('Starting new dnsmasq: %s' % ' '.join(cmd))
check_call(cmd)
if __name__ == '__main__':
if not os.path.isfile(config['hosts_file']):
with open(config['hosts_file'], 'wb'):
pass
ensure_dnsmasq()
listen()
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