Simple implementation of DNSMasq backend

The logic is quite simple. All dns zones are stored in separate files.
They are eventually merged into one flat dns zone.
And this file (or any separate zone) should be specified in dnsmasq config file (--addn-hosts=).
Update is also simple, all you need is to send a SIGHUP to dnsmasq to force re-read of the file.

Change-Id: Id634ca2843fd02a8406913881d4989c7c2112249

moniker/backend/impl_dnsmasq.py

@@ -0,0 +1,120 @@
+# Copyright 2012 Managed I.T.
+#
+# Author: Kiall Mac Innes <kiall@managedit.ie>
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+import os
+import shutil
+from moniker.openstack.common import cfg
+from moniker.openstack.common import log as logging
+from moniker import utils
+from moniker.backend import base
+from moniker.context import MonikerContext
+
+LOG = logging.getLogger(__name__)
+
+
+class DnsmasqBackend(base.Backend):
+    __plugin_name__ = 'dnsmasq'
+
+    def start(self):
+        super(DnsmasqBackend, self).start()
+
+        output_folder = os.path.join(os.path.abspath(cfg.CONF.state_path),
+                                     'dnsmasq')
+
+        # Create the output folder tree if necessary
+        if not os.path.exists(output_folder):
+            os.makedirs(output_folder)
+
+        # TODO: This is a hack to ensure the data dir is 100% up to date
+        admin_context = MonikerContext.get_admin_context()
+
+        domains = self.central_service.get_domains(admin_context)
+        for domain in domains:
+            self._sync_domain(domain)
+        self._sync_domains()
+
+    def create_domain(self, context, domain):
+        LOG.debug('Create Domain')
+        self._sync_domain(domain)
+
+    def update_domain(self, context, domain):
+        LOG.debug('Update Domain')
+        self._sync_domain(domain)
+
+    def delete_domain(self, context, domain):
+        LOG.debug('Delete Domain')
+        self._sync_delete_domain(domain)
+
+    def create_record(self, context, domain, record):
+        LOG.debug('Create Record')
+        self._sync_domain(domain)
+
+    def update_record(self, context, domain, record):
+        LOG.debug('Update Record')
+        self._sync_domain(domain)
+
+    def delete_record(self, context, domain, record):
+        LOG.debug('Delete Record')
+        self._sync_domain(domain)
+
+    def _sync_domains(self):
+        """ Sync the list of domains this server handles """
+        LOG.debug('Synchronising domains')
+
+        admin_context = MonikerContext.get_admin_context()
+        domains = self.central_service.get_domains(admin_context)
+
+        output_path = os.path.join(os.path.abspath(cfg.CONF.state_path),
+                                   'dnsmasq', 'flatdns.zone')
+
+        output_file = open(output_path, 'w+')
+        for domain in domains:
+            zone_file = os.path.join(os.path.abspath(cfg.CONF.state_path),
+                                     'dnsmasq', '%s.zone' % domain['id'])
+            LOG.debug('Merging %s' % zone_file)
+            if os.path.exists(zone_file):
+                shutil.copyfileobj(open(zone_file, 'r'), output_file)
+        output_file.close()
+
+        # Send HUP to dnsmasq
+        utils.execute('killall', '-HUP', 'dnsmasq')
+
+    def _sync_delete_domain(self, domain):
+        """ Remove domain zone files rebuild flat zone """
+        LOG.debug('Delete Domain: %s' % domain['id'])
+
+        output_folder = os.path.join(os.path.abspath(cfg.CONF.state_path),
+                                     'dnsmasq')
+
+        output_path = os.path.join(output_folder, '%s.zone' % domain['id'])
+        os.remove(output_path)
+        self._sync_domains()
+
+    def _sync_domain(self, domain):
+        """ Sync a single domain's zone file """
+        LOG.debug('Synchronising Domain: %s' % domain['id'])
+
+        admin_context = MonikerContext.get_admin_context()
+        records = self.central_service.get_records(admin_context, domain['id'])
+
+        output_folder = os.path.join(os.path.abspath(cfg.CONF.state_path),
+                                     'dnsmasq')
+
+        output_path = os.path.join(output_folder, '%s.zone' % domain['id'])
+        utils.render_template_to_file('dnsmasq-zone.jinja2',
+                                      output_path,
+                                      records=records)
+
+        self._sync_domains()

moniker/resources/templates/dnsmasq-zone.jinja2

@@ -0,0 +1,3 @@
+{% for record in records if record.type in ['A', 'AAAA'] %}
+{{record.data}} {{record.name}}
+{%- endfor %}

setup.py

@@ -69,6 +69,7 @@ setup(
         mysqlbind9 = moniker.backend.impl_mysqlbind9:MySQLBind9Backend
         powerdns = moniker.backend.impl_powerdns:PowerDNSBackend
         rpc = moniker.backend.impl_rpc:RPCBackend
+        dnsmasq = moniker.backend.impl_dnsmasq:DnsmasqBackend
         fake = moniker.backend.impl_fake:FakeBackend
 
         [moniker.manage]