Send IP advertisements when plugging a new member subnet

When plugging a new subnet, the amphora sends a packet advertising the
IP address of the port. In case previously deallocated IP addresses are
re-used, it helps the other resources on the same L2 network to flush
the old ARP entries.

Closes-Bug: #2015572

Change-Id: Iecedb9e9c8f293cd4c067900e1696f5050769ee8

octavia/amphorae/backends/agent/api_server/plug.py

@@ -24,6 +24,7 @@ import pyroute2
 import webob
 from werkzeug import exceptions
 
+from octavia.amphorae.backends.agent.api_server import util
 from octavia.common import constants as consts
 
 
@@ -196,6 +197,8 @@ class Plug(object):
                     fixed_ips=fixed_ips,
                     mtu=mtu)
                 self._osutils.bring_interface_up(existing_interface, 'network')
+
+            util.send_member_advertisements(fixed_ips)
             return webob.Response(json={
                 'message': "OK",
                 'details': "Updated existing interface {interface}".format(
@@ -236,6 +239,7 @@ class Plug(object):
                      IFLA_IFNAME=netns_interface)
 
         self._osutils.bring_interface_up(netns_interface, 'network')
+        util.send_member_advertisements(fixed_ips)
 
         return webob.Response(json={
             'message': "OK",

octavia/amphorae/backends/agent/api_server/util.py

@@ -17,6 +17,7 @@ import os
 import re
 import stat
 import subprocess
+import typing as tp
 
 import jinja2
 from oslo_config import cfg
@@ -411,3 +412,23 @@ def send_vip_advertisements(lb_id):
     except Exception as e:
         LOG.debug('Send VIP advertisement failed due to :%s. '
                   'This amphora may not be the MASTER. Ignoring.', str(e))
+
+
+def send_member_advertisements(fixed_ips: tp.Iterable[tp.Dict[str, str]]):
+    """Sends advertisements for each fixed_ip of a list
+
+    This method will send either GARP (IPv4) or neighbor advertisements (IPv6)
+    for the addresses of the subnets of the members.
+
+    :param fixed_ips: a list of dicts that contain 'ip_address' elements
+    :returns: None
+    """
+    try:
+        for fixed_ip in fixed_ips:
+            ip_address = fixed_ip[consts.IP_ADDRESS]
+            interface = network_utils.get_interface_name(
+                ip_address, net_ns=consts.AMPHORA_NAMESPACE)
+            ip_advertisement.send_ip_advertisement(
+                interface, ip_address, net_ns=consts.AMPHORA_NAMESPACE)
+    except Exception as e:
+        LOG.debug('Send member advertisement failed due to: %s', str(e))

octavia/tests/unit/amphorae/backends/agent/api_server/test_plug.py

@@ -265,7 +265,10 @@ class TestPlug(base.TestCase):
                 "BaseOS.write_port_interface_file")
     @mock.patch("octavia.amphorae.backends.agent.api_server.osutils."
                 "BaseOS.bring_interface_up")
-    def test_plug_network(self, mock_if_up, mock_write_port_interface,
+    @mock.patch("octavia.amphorae.backends.agent.api_server.util."
+                "send_member_advertisements")
+    def test_plug_network(self, mock_send_member_adv,
+                          mock_if_up, mock_write_port_interface,
                           mock_netns, mock_iproute,
                           mock_by_mac, mock_interface_exists, mock_webob):
         fixed_ips = [
@@ -284,6 +287,7 @@ class TestPlug(base.TestCase):
         mock_write_port_interface.assert_called_once_with(
             interface='eth0', fixed_ips=fixed_ips, mtu=mtu)
         mock_if_up.assert_called_once_with('eth0', 'network')
+        mock_send_member_adv.assert_called_once_with(fixed_ips)
 
         mock_webob.Response.assert_any_call(
             json={'message': 'OK',
@@ -300,7 +304,10 @@ class TestPlug(base.TestCase):
                 "BaseOS.write_port_interface_file")
     @mock.patch("octavia.amphorae.backends.agent.api_server.osutils."
                 "BaseOS.bring_interface_up")
-    def test_plug_network_existing_interface(self, mock_if_up,
+    @mock.patch("octavia.amphorae.backends.agent.api_server.util."
+                "send_member_advertisements")
+    def test_plug_network_existing_interface(self, mock_send_member_adv,
+                                             mock_if_up,
                                              mock_write_port_interface,
                                              mock_netns, mock_by_mac,
                                              mock_interface_exists,
@@ -327,6 +334,7 @@ class TestPlug(base.TestCase):
         mock_write_port_interface.assert_called_once_with(
             interface=FAKE_INTERFACE, fixed_ips=fixed_ips, mtu=mtu)
         mock_if_up.assert_called_once_with(FAKE_INTERFACE, 'network')
+        mock_send_member_adv.assert_called_once_with(fixed_ips)
 
         mock_webob.Response.assert_any_call(
             json={'message': 'OK',
@@ -344,8 +352,10 @@ class TestPlug(base.TestCase):
                 "BaseOS.write_vip_interface_file")
     @mock.patch("octavia.amphorae.backends.agent.api_server.osutils."
                 "BaseOS.bring_interface_up")
+    @mock.patch("octavia.amphorae.backends.agent.api_server.util."
+                "send_member_advertisements")
     def test_plug_network_on_vip(
-            self, mock_if_up, mock_write_vip_interface,
+            self, mock_send_member_adv, mock_if_up, mock_write_vip_interface,
             mock_netns, mock_by_mac, mock_interface_exists, mock_webob):
         fixed_ips = [
             {'ip_address': FAKE_IP_IPV4,
@@ -394,6 +404,7 @@ class TestPlug(base.TestCase):
             fixed_ips=fixed_ips, mtu=mtu)
 
         mock_if_up.assert_called_once_with(FAKE_INTERFACE, 'vip')
+        mock_send_member_adv.assert_called_once_with(fixed_ips)
 
         mock_webob.Response.assert_any_call(
             json={'message': 'OK',

octavia/tests/unit/amphorae/backends/agent/api_server/test_util.py

@@ -406,3 +406,38 @@ class TestUtil(base.TestCase):
         util.send_vip_advertisements(LB_ID1)
         mock_get_int_name.assert_not_called()
         mock_send_advert.assert_not_called()
+
+    @mock.patch('octavia.amphorae.backends.utils.ip_advertisement.'
+                'send_ip_advertisement')
+    @mock.patch('octavia.amphorae.backends.utils.network_utils.'
+                'get_interface_name')
+    def test_send_member_advertisements(self, mock_get_int_name,
+                                        mock_send_advert):
+        # IPv4 fixed_ips
+        mock_get_int_name.side_effect = ['fake0', 'fake1']
+        fixed_ips = [{'ip_address': '192.0.2.1'},
+                     {'ip_address': '192.2.0.2'}]
+        util.send_member_advertisements(fixed_ips)
+        mock_send_advert.assert_has_calls(
+            [mock.call('fake0', fixed_ips[0]['ip_address'],
+                       net_ns=consts.AMPHORA_NAMESPACE),
+             mock.call('fake1', fixed_ips[1]['ip_address'],
+                       net_ns=consts.AMPHORA_NAMESPACE)])
+
+        # Mixed IPv4/IPv6
+        mock_send_advert.reset_mock()
+        mock_get_int_name.side_effect = ['fake0', 'fake1']
+        fixed_ips = [{'ip_address': '192.0.2.1'},
+                     {'ip_address': '2001:db8::2'}]
+        util.send_member_advertisements(fixed_ips)
+        mock_send_advert.assert_has_calls(
+            [mock.call('fake0', fixed_ips[0]['ip_address'],
+                       net_ns=consts.AMPHORA_NAMESPACE),
+             mock.call('fake1', fixed_ips[1]['ip_address'],
+                       net_ns=consts.AMPHORA_NAMESPACE)])
+
+        # Exception
+        mock_send_advert.reset_mock()
+        mock_get_int_name.side_effect = Exception('ERROR')
+        util.send_member_advertisements(fixed_ips)
+        mock_send_advert.assert_not_called()

releasenotes/notes/members-subnet-ip-advertisements-af2264844079ef6b.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    When plugging a new member subnet, the amphora sends an IP advertisement of
+    the newly allocated IP. It allows the servers on the same L2 network to
+    flush the ARP entries of a previously allocated IP address.