Add both IPv4 and IPv6 DHCP options if interface has both

It is possible that an interface has both IPv4 and IPv6 addresses,
primarily when using SLAAC with OpenStack Neutron.  When this is
the case, it is very likely that the first fixed IP would be a
SLAAC assigned port and the second IP is the IPv4 address.

In an environment where you are looking to boot via IPv4, no DHCPv6
infrastructure exists as IPv6 connectivity is provided via SLAAC,
you would not be able to use this network to boot off of.

This patch instead grabs all the fixed IP addresses, then inserts
the options that match the IP versions which are attached to the
interface, potentially resulting in both IPv4 and IPv6 options
being included (though the IPv6 ones would be largely omitted).

In environments where only IPv4 or IPv6 is in use on the port, it
will still only insert the options for those specific IP versions.

Story #2008660
Task #41933
Change-Id: I52e4ee022b17cb7f007534cb368136567b139a34

ironic/dhcp/neutron.py

@@ -64,9 +64,8 @@ class NeutronDHCPApi(base.BaseDHCP):
         try:
             neutron_client = neutron.get_client(token=token, context=context)
 
-            fip = None
+            fips = []
             port = neutron_client.get_port(port_id)
-            try:
             if port:
                 # TODO(TheJulia): We need to retool this down the
                 # road so that we handle ports and allow preferences
@@ -77,12 +76,13 @@ class NeutronDHCPApi(base.BaseDHCP):
                 # with UEFI machines, so the support matrix also gets
                 # a little "weird".
                 # Ideally, we should work on this in Victoria.
-                    fip = port.get('fixed_ips')[0]
+                fips = port.get('fixed_ips')
-            except (TypeError, IndexError):
+
-                fip = None
             update_opts = []
-            if fip:
+            if len(fips) != 0:
-                ip_version = ipaddress.ip_address(fip['ip_address']).version
+                for fip in fips:
+                    ip_version = \
+                        ipaddress.ip_address(fip['ip_address']).version
                     for option in dhcp_options:
                         if option.get('ip_version', 4) == ip_version:
                             update_opts.append(option)

ironic/tests/unit/dhcp/test_neutron.py

@@ -119,6 +119,66 @@ class TestNeutron(db_base.DbTestCase):
         update_mock.assert_called_once_with(
             task.context, port_id, expected)
 
+    @mock.patch('ironic.common.neutron.get_client', autospec=True)
+    @mock.patch('ironic.common.neutron.update_neutron_port', autospec=True)
+    def test_update_port_dhcp_opts_v4_and_v6(self, update_mock, client_mock):
+        opts = [{'opt_name': 'bootfile-name',
+                 'opt_value': 'pxelinux.0',
+                 'ip_version': 4},
+                {'opt_name': 'tftp-server',
+                 'opt_value': '1.1.1.1',
+                 'ip_version': 4},
+                {'opt_name': 'server-ip-address',
+                 'opt_value': '1.1.1.1',
+                 'ip_version': 4},
+                {'opt_name': 'bootfile-url',
+                 'opt_value': 'tftp://::1/file.name',
+                 'ip_version': 6}]
+        port_id = 'fake-port-id'
+        expected = {
+            'extra_dhcp_opts': [
+                {
+                    'opt_name': 'bootfile-name',
+                    'opt_value': 'pxelinux.0',
+                    'ip_version': 4
+                },
+                {
+                    'opt_name': 'tftp-server',
+                    'opt_value': '1.1.1.1',
+                    'ip_version': 4
+                },
+                {
+                    'opt_name': 'server-ip-address',
+                    'opt_value': '1.1.1.1',
+                    'ip_version': 4
+                },
+                {
+                    'opt_name': 'bootfile-url',
+                    'opt_value': 'tftp://::1/file.name',
+                    'ip_version': 6
+                }
+            ]
+        }
+        port_data = {
+            "id": port_id,
+            "fixed_ips": [
+                {
+                    "ip_address": "192.168.1.3",
+                },
+                {
+                    "ip_address": "2001:db8::201",
+                }
+            ],
+        }
+        client_mock.return_value.get_port.return_value = port_data
+
+        api = dhcp_factory.DHCPFactory()
+        with task_manager.acquire(self.context, self.node.uuid) as task:
+            api.provider.update_port_dhcp_opts(port_id, opts,
+                                               context=task.context)
+        update_mock.assert_called_once_with(
+            task.context, port_id, expected)
+
     @mock.patch('ironic.common.neutron.get_client', autospec=True)
     @mock.patch('ironic.common.neutron.update_neutron_port', autospec=True)
     def test_update_port_dhcp_opts_with_exception(self, update_mock,

releasenotes/notes/add-dual-stack-dhcp-opts-6dc18ae10aeb599a.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - When using the Neutron DHCP driver, Ironic would only use the first fixed
+    IP address to determine what IP versions are use on the port.  Now, it
+    checks for all the IP addresses and adds DHCP options for all IP versions.