DigitalOcean: bind resolvers to loopback interface.

This change makes the DigitalOcean datasource consistent with OpenStack and
Joyent by binding the resolver addresses to the loopback interface. This _is_
a work-around to bug 1675571.

Part of bug 1676908.

2 files changed, 34 insertions, 30 deletions

diff --git a/cloudinit/sources/helpers/digitalocean.py b/cloudinit/sources/helpers/digitalocean.py
index 72f7bde4..6423c8ef 100644
--- a/cloudinit/sources/helpers/digitalocean.py
+++ b/cloudinit/sources/helpers/digitalocean.py
@@ -107,15 +107,12 @@ def convert_network_configuration(config, dns_servers):
         }
     """
 
-    def _get_subnet_part(pcfg, nameservers=None):
+    def _get_subnet_part(pcfg):
         subpart = {'type': 'static',
                    'control': 'auto',
                    'address': pcfg.get('ip_address'),
                    'gateway': pcfg.get('gateway')}
 
-        if nameservers:
-            subpart['dns_nameservers'] = nameservers
-
         if ":" in pcfg.get('ip_address'):
             subpart['address'] = "{0}/{1}".format(pcfg.get('ip_address'),
                                                   pcfg.get('cidr'))
@@ -157,13 +154,8 @@ def convert_network_configuration(config, dns_servers):
                 continue
 
             sub_part = _get_subnet_part(raw_subnet)
-            if nic_type == 'public' and 'anchor' not in netdef:
-                # add DNS resolvers to the public interfaces only
-                sub_part = _get_subnet_part(raw_subnet, dns_servers)
-            else:
-                # remove the gateway any non-public interfaces
-                if 'gateway' in sub_part:
-                    del sub_part['gateway']
+            if netdef in ('private', 'anchor_ipv4', 'anchor_ipv6'):
+                del sub_part['gateway']
 
             subnets.append(sub_part)
 
@@ -171,6 +163,10 @@ def convert_network_configuration(config, dns_servers):
         nic_configs.append(ncfg)
         LOG.debug("nic '%s' configuration: %s", if_name, ncfg)
 
+    if dns_servers:
+        LOG.debug("added dns servers: %s", dns_servers)
+        nic_configs.append({'type': 'nameserver', 'address': dns_servers})
+
     return {'version': 1, 'config': nic_configs}
 
 
diff --git a/tests/unittests/test_datasource/test_digitalocean.py b/tests/unittests/test_datasource/test_digitalocean.py
index 61d6e001..a11166a9 100644
--- a/tests/unittests/test_datasource/test_digitalocean.py
+++ b/tests/unittests/test_datasource/test_digitalocean.py
@@ -197,7 +197,8 @@ class TestNetworkConvert(TestCase):
     @mock.patch('cloudinit.net.get_interfaces_by_mac')
     def _get_networking(self, m_get_by_mac):
         m_get_by_mac.return_value = {
-            '04:01:57:d1:9e:01': 'ens1', '04:01:57:d1:9e:02': 'ens2',
+            '04:01:57:d1:9e:01': 'ens1',
+            '04:01:57:d1:9e:02': 'ens2',
             'b8:ae:ed:75:5f:9a': 'enp0s25',
             'ae:cc:08:7c:88:00': 'meta2p1'}
         netcfg = digitalocean.convert_network_configuration(
@@ -208,18 +209,33 @@ class TestNetworkConvert(TestCase):
     def test_networking_defined(self):
         netcfg = self._get_networking()
         self.assertIsNotNone(netcfg)
+        dns_defined = False
 
-        for nic_def in netcfg.get('config'):
-            print(json.dumps(nic_def, indent=3))
-            n_type = nic_def.get('type')
-            n_subnets = nic_def.get('type')
-            n_name = nic_def.get('name')
-            n_mac = nic_def.get('mac_address')
+        for part in netcfg.get('config'):
+            n_type = part.get('type')
+            print("testing part ", n_type, "\n", json.dumps(part, indent=3))
+
+            if n_type == 'nameserver':
+                n_address = part.get('address')
+                self.assertIsNotNone(n_address)
+                self.assertEqual(len(n_address), 3)
+
+                dns_resolvers = DO_META["dns"]["nameservers"]
+                for x in n_address:
+                    self.assertIn(x, dns_resolvers)
+                dns_defined = True
 
-            self.assertIsNotNone(n_type)
-            self.assertIsNotNone(n_subnets)
-            self.assertIsNotNone(n_name)
-            self.assertIsNotNone(n_mac)
+            else:
+                n_subnets = part.get('type')
+                n_name = part.get('name')
+                n_mac = part.get('mac_address')
+
+                self.assertIsNotNone(n_type)
+                self.assertIsNotNone(n_subnets)
+                self.assertIsNotNone(n_name)
+                self.assertIsNotNone(n_mac)
+
+        self.assertTrue(dns_defined)
 
     def _get_nic_definition(self, int_type, expected_name):
         """helper function to return if_type (i.e. public) and the expected
@@ -260,12 +276,6 @@ class TestNetworkConvert(TestCase):
         self.assertEqual(meta_def.get('mac'), nic_def.get('mac_address'))
         self.assertEqual('physical', nic_def.get('type'))
 
-    def _check_dns_nameservers(self, subn_def):
-        self.assertIn('dns_nameservers', subn_def)
-        expected_nameservers = DO_META['dns']['nameservers']
-        nic_nameservers = subn_def.get('dns_nameservers')
-        self.assertEqual(expected_nameservers, nic_nameservers)
-
     def test_public_interface_ipv6(self):
         """test public ipv6 addressing"""
         (nic_def, meta_def) = self._get_nic_definition('public', 'eth0')
@@ -280,7 +290,6 @@ class TestNetworkConvert(TestCase):
 
         self.assertEqual(cidr_notated_address, subn_def.get('address'))
         self.assertEqual(ipv6_def.get('gateway'), subn_def.get('gateway'))
-        self._check_dns_nameservers(subn_def)
 
     def test_public_interface_ipv4(self):
         """test public ipv4 addressing"""
@@ -293,7 +302,6 @@ class TestNetworkConvert(TestCase):
 
         self.assertEqual(ipv4_def.get('netmask'), subn_def.get('netmask'))
         self.assertEqual(ipv4_def.get('gateway'), subn_def.get('gateway'))
-        self._check_dns_nameservers(subn_def)
 
     def test_public_interface_anchor_ipv4(self):
         """test public ipv4 addressing"""