Validate [designate] ipvN_ptr_zone_prefix_size at config layer

This change re-implements validation of ipvN_ptr_zone_prefix_size at
config definition layer. This brings a few benefits.
 - The validation is executed at an earlier stage
 - The validation can be leveraged by the oslo-config-validator.

Change-Id: Ib72109bcb537b3e44719efb6f33ea46f0d45a1ef

neutron/conf/services/extdns_designate_driver.py

@@ -15,9 +15,35 @@
 
 from keystoneauth1 import loading
 from oslo_config import cfg
+from oslo_config import types
 
 from neutron._i18n import _
 
+
+class ZonePrefixIPv4(types.Integer):
+    def __init__(self):
+        super(ZonePrefixIPv4, self).__init__(
+            min=8, max=24, type_name='IPv4 zone prefix')
+
+    def __call__(self, value):
+        value = super(ZonePrefixIPv4, self).__call__(value)
+        if value % 8 != 0:
+            raise ValueError(_('Should be multiple of 8'))
+        return value
+
+
+class ZonePrefixIPv6(types.Integer):
+    def __init__(self):
+        super(ZonePrefixIPv6, self).__init__(
+            min=4, max=124, type_name='IPv6 zone prefix')
+
+    def __call__(self, value):
+        value = super(ZonePrefixIPv6, self).__call__(value)
+        if value % 4 != 0:
+            raise ValueError(_('Should be multiple of 4'))
+        return value
+
+
 designate_opts = [
     cfg.StrOpt('url',
                help=_('URL for connecting to designate')),
@@ -59,14 +85,16 @@ designate_opts = [
                       'context')),
     cfg.BoolOpt('allow_reverse_dns_lookup', default=True,
                 help=_('Allow the creation of PTR records')),
-    cfg.IntOpt(
+    cfg.Opt(
         'ipv4_ptr_zone_prefix_size', default=24,
+        type=ZonePrefixIPv4(),
         help=_('Number of bits in an IPv4 PTR zone that will be considered '
                'network prefix. It has to align to byte boundary. Minimum '
                'value is 8. Maximum value is 24. As a consequence, range '
                'of values is 8, 16 and 24')),
-    cfg.IntOpt(
+    cfg.Opt(
         'ipv6_ptr_zone_prefix_size', default=120,
+        type=ZonePrefixIPv6(),
         help=_('Number of bits in an IPv6 PTR zone that will be considered '
                'network prefix. It has to align to nyble boundary. Minimum '
                'value is 4. Maximum value is 124. As a consequence, range '

neutron/services/externaldns/drivers/designate/driver.py

@@ -28,11 +28,6 @@ from oslo_log import log
 from neutron.conf.services import extdns_designate_driver
 from neutron.services.externaldns import driver
 
-IPV4_PTR_ZONE_PREFIX_MIN_SIZE = 8
-IPV4_PTR_ZONE_PREFIX_MAX_SIZE = 24
-IPV6_PTR_ZONE_PREFIX_MIN_SIZE = 4
-IPV6_PTR_ZONE_PREFIX_MAX_SIZE = 124
-
 _SESSION = None
 
 CONF = cfg.CONF
@@ -74,26 +69,6 @@ def get_all_projects_client(context):
 class Designate(driver.ExternalDNSService):
     """Driver for Designate."""
 
-    def __init__(self):
-        ipv4_ptr_zone_size = CONF.designate.ipv4_ptr_zone_prefix_size
-        ipv6_ptr_zone_size = CONF.designate.ipv6_ptr_zone_prefix_size
-
-        if (ipv4_ptr_zone_size < IPV4_PTR_ZONE_PREFIX_MIN_SIZE or
-                ipv4_ptr_zone_size > IPV4_PTR_ZONE_PREFIX_MAX_SIZE or
-                (ipv4_ptr_zone_size % 8) != 0):
-            raise dns_exc.InvalidPTRZoneConfiguration(
-                parameter='ipv4_ptr_zone_size', number='8',
-                maximum=str(IPV4_PTR_ZONE_PREFIX_MAX_SIZE),
-                minimum=str(IPV4_PTR_ZONE_PREFIX_MIN_SIZE))
-
-        if (ipv6_ptr_zone_size < IPV6_PTR_ZONE_PREFIX_MIN_SIZE or
-                ipv6_ptr_zone_size > IPV6_PTR_ZONE_PREFIX_MAX_SIZE or
-                (ipv6_ptr_zone_size % 4) != 0):
-            raise dns_exc.InvalidPTRZoneConfiguration(
-                parameter='ipv6_ptr_zone_size', number='4',
-                maximum=str(IPV6_PTR_ZONE_PREFIX_MAX_SIZE),
-                minimum=str(IPV6_PTR_ZONE_PREFIX_MIN_SIZE))
-
     def create_record_set(self, context, dns_domain, dns_name, records):
         designate, designate_admin = get_clients(context)
         v4, v6 = self._classify_records(records)

neutron/tests/unit/services/externaldns/drivers/designate/test_driver.py

@@ -254,25 +254,37 @@ class TestDesignateDriver(base.BaseTestCase):
         )
 
     def test_ipv4_ptr_is_misconfigured(self):
-        cfg.CONF.set_override(
-            'ipv4_ptr_zone_prefix_size', -1, group='designate'
+        self.assertRaises(
+            ValueError,
+            cfg.CONF.set_override,
+            'ipv4_ptr_zone_prefix_size', 0, group='designate'
+        )
+        self.assertRaises(
+            ValueError,
+            cfg.CONF.set_override,
+            'ipv4_ptr_zone_prefix_size', 32, group='designate'
         )
-
         self.assertRaisesRegex(
-            dns_exc.InvalidPTRZoneConfiguration,
-            'Value of ipv4_ptr_zone_size has to be multiple of 8, with '
-            'maximum value of 24 and minimum value of 8',
-            driver.Designate
+            ValueError,
+            'Should be multiple of 8',
+            cfg.CONF.set_override,
+            'ipv4_ptr_zone_prefix_size', 9, group='designate'
         )
 
     def test_ipv6_ptr_is_misconfigured(self):
-        cfg.CONF.set_override(
-            'ipv6_ptr_zone_prefix_size', -1, group='designate'
+        self.assertRaises(
+            ValueError,
+            cfg.CONF.set_override,
+            'ipv6_ptr_zone_prefix_size', 0, group='designate'
+        )
+        self.assertRaises(
+            ValueError,
+            cfg.CONF.set_override,
+            'ipv6_ptr_zone_prefix_size', 128, group='designate'
         )
-
         self.assertRaisesRegex(
-            dns_exc.InvalidPTRZoneConfiguration,
-            'Value of ipv6_ptr_zone_size has to be multiple of 4, with '
-            'maximum value of 124 and minimum value of 4',
-            driver.Designate
+            ValueError,
+            'Should be multiple of 4',
+            cfg.CONF.set_override,
+            'ipv6_ptr_zone_prefix_size', 5, group='designate'
         )