diff --git a/unit_tests/utilities/test_zaza_utilities_openstack.py b/unit_tests/utilities/test_zaza_utilities_openstack.py
index 5c344bfdc..308320483 100644
--- a/unit_tests/utilities/test_zaza_utilities_openstack.py
+++ b/unit_tests/utilities/test_zaza_utilities_openstack.py
@@ -1216,3 +1216,33 @@ def test_ovn_present(self):
         self.assertTrue(openstack_utils.ovn_present())
         self.get_application.side_effect = [KeyError, KeyError]
         self.assertFalse(openstack_utils.ovn_present())
+
+    def test_configure_gateway_ext_port(self):
+        # FIXME: this is not a complete unit test for the function as one did
+        # not exist at all I'm adding this to test one bit and we'll add more
+        # as we go.
+        self.patch_object(openstack_utils, 'deprecated_external_networking')
+        self.patch_object(openstack_utils, 'dvr_enabled')
+        self.patch_object(openstack_utils, 'ovn_present')
+        self.patch_object(openstack_utils, 'get_gateway_uuids')
+        self.patch_object(openstack_utils, 'get_admin_net')
+        self.dvr_enabled = False
+        self.ovn_present = False
+        self.get_admin_net.return_value = {'id': 'fakeid'}
+
+        novaclient = mock.MagicMock()
+        neutronclient = mock.MagicMock()
+
+        def _fake_empty_generator(empty=True):
+            if empty:
+                return
+            yield
+
+        self.get_gateway_uuids.side_effect = _fake_empty_generator
+        with self.assertRaises(RuntimeError):
+            openstack_utils.configure_gateway_ext_port(
+                novaclient, neutronclient)
+        # provide a uuid and check that we don't raise RuntimeError
+        self.get_gateway_uuids.side_effect = ['fake-uuid']
+        openstack_utils.configure_gateway_ext_port(
+            novaclient, neutronclient)
diff --git a/zaza/openstack/utilities/openstack.py b/zaza/openstack/utilities/openstack.py
index 47cabf367..ea2a6ba51 100644
--- a/zaza/openstack/utilities/openstack.py
+++ b/zaza/openstack/utilities/openstack.py
@@ -732,6 +732,7 @@ def configure_gateway_ext_port(novaclient, neutronclient, net_id=None,
     if not net_id:
         net_id = get_admin_net(neutronclient)['id']
 
+    ports_created = 0
     for uuid in uuids:
         server = novaclient.servers.get(uuid)
         ext_port_name = "{}_ext-port".format(server.name)
@@ -752,12 +753,19 @@ def configure_gateway_ext_port(novaclient, neutronclient, net_id=None,
                 }
             }
             port = neutronclient.create_port(body=body_value)
+            ports_created += 1
             server.interface_attach(port_id=port['port']['id'],
                                     net_id=None, fixed_ip=None)
             if add_dataport_to_netplan:
                 mac_address = get_mac_from_port(port, neutronclient)
                 add_interface_to_netplan(server.name,
                                          mac_address=mac_address)
+    if not ports_created:
+        # NOTE: uuids is an iterator so testing it for contents or length prior
+        # to iterating over it is futile.
+        raise RuntimeError('Unable to determine UUIDs for machines to attach '
+                           'external networking to.')
+
     ext_br_macs = []
     for port in neutronclient.list_ports(network_id=net_id)['ports']:
         if 'ext-port' in port['name']: