fix: leave an unchanged Kea reservation and Kea alone

create_dhcp_reservation rewrote an existing reservation and called
service/reconfigure even when it already held exactly what was asked, e.g.
on a retried provisioning job. reconfigure stops and starts Kea (the Kea
service controller keeps reconfigureForceRestart() = true and configd has no
reload action), which once left a firewall without DHCP. A reservation whose
subnet, MAC (normalised), IP, hostname and description already match is now
left alone.

Refs NetOrk/netork#1187

tests/unit/test_driver.py

@@ -1787,6 +1787,83 @@ class TestCreateDhcpReservation:
             == "https://opnsense.example.com/api/kea/dhcpv4/setReservation/existing-uuid-456"
         )
 
+    # A reconfigure stops and starts Kea (ApiMutableServiceControllerBase,
+    # reconfigureForceRestart() is true for Kea). Writing a reservation that
+    # is already there, and restarting the daemon for it, once left a
+    # firewall without DHCP (#1187) -- so an unchanged one is not touched.
+
+    @pytest.mark.parametrize(
+        "subnet",
+        ["172.22.8.0/24", "6854cab3-ebb5-4031-b987-0edcc6723546"],
+        ids=["subnet-as-cidr", "subnet-as-uuid"],
+    )
+    def test_unchanged_reservation_is_neither_written_nor_reconfigured(self, driver, subnet):
+        driver.session.get.return_value = _make_json_response(KEA_SUBNETS_RESPONSE)
+        driver.session.post.side_effect = [
+            _make_json_response(
+                {
+                    "rows": [
+                        {
+                            "uuid": "existing-uuid-456",
+                            "subnet": subnet,
+                            "ip_address": "172.22.8.253",
+                            # Kea keeps the MAC as it was entered -- case and
+                            # separator do not make it a different reservation.
+                            "hw_address": "02-AA-BB-CC-DD-EE",
+                            "hostname": "new-vm",
+                            "description": "[netork]",
+                        }
+                    ]
+                }
+            ),
+        ]
+
+        driver.create_dhcp_reservation(
+            mac="02:aa:bb:cc:dd:ee", ip="172.22.8.253", hostname="new-vm"
+        )
+
+        # searchReservation only -- no setReservation, no service/reconfigure.
+        assert driver.session.post.call_count == 1
+
+    @pytest.mark.parametrize(
+        "field, live_value",
+        [
+            ("hw_address", "02:aa:bb:cc:dd:ff"),
+            ("hostname", "old-vm"),
+            ("description", "made by hand"),
+            ("subnet", "172.22.0.0/24"),
+        ],
+    )
+    def test_reservation_differing_in_one_field_is_written_and_reconfigured(
+        self, driver, field, live_value
+    ):
+        row = {
+            "uuid": "existing-uuid-456",
+            "subnet": "172.22.8.0/24",
+            "ip_address": "172.22.8.253",
+            "hw_address": "02:aa:bb:cc:dd:ee",
+            "hostname": "new-vm",
+            "description": "[netork]",
+        }
+        row[field] = live_value
+        driver.session.get.return_value = _make_json_response(KEA_SUBNETS_RESPONSE)
+        driver.session.post.side_effect = [
+            _make_json_response({"rows": [row]}),
+            _make_json_response({"result": "saved", "uuid": "existing-uuid-456"}),
+            _make_json_response({"status": "ok"}),
+        ]
+
+        driver.create_dhcp_reservation(
+            mac="02:aa:bb:cc:dd:ee", ip="172.22.8.253", hostname="new-vm"
+        )
+
+        paths = [c.args[0] for c in driver.session.post.call_args_list]
+        assert paths == [
+            "https://opnsense.example.com/api/kea/dhcpv4/searchReservation",
+            "https://opnsense.example.com/api/kea/dhcpv4/setReservation/existing-uuid-456",
+            "https://opnsense.example.com/api/kea/service/reconfigure",
+        ]
+
     def test_raises_when_ip_not_in_any_kea_subnet(self, driver):
         driver.session.get.return_value = _make_json_response(KEA_SUBNETS_RESPONSE)