fix(instances): clone name and MAC read the same dhcpd.conf

An optional dhcpd.conf next to the application supplies clone names and
their MAC addresses. get_dhcp_mac_address read it from BASE_DIR, but
guess_clone_name from a fixed /srv/webvirtcloud/dhcpd.conf, so on any
other install path the Guess button found no name while the MAC lookup
still worked. Both use utils.dhcpd_conf() (BASE_DIR) now.

instances/test_clone_permission.py

@@ -2,18 +2,21 @@
 Cloning another user's VM must require change permission on it (templates
 excepted), and the clone data must not be taken blindly from the POST body.
 """
+import tempfile
 from contextlib import contextmanager
+from pathlib import Path
 from unittest.mock import patch
 
 from django.contrib.auth import get_user_model
 from django.contrib.auth.models import Permission
-from django.test import TestCase
+from django.test import TestCase, override_settings
 from django.urls import reverse
 
 from accounts.models import UserInstance
 from appsettings.settings import app_settings
 from computes.models import Compute
 from instances.models import Instance
+from instances.utils import get_dhcp_mac_address
 
 SRC_DISK = {
     "dev": "vda",
@@ -201,3 +204,19 @@ class ClonePermissionTestCase(TestCase):
         self.assertEqual(
             proxy.clone_instance.call_args[0][0]["disk-vda"], "my-disk-2-clone.qcow2"
         )
+
+
+class DhcpdConfTestCase(TestCase):
+    """Clone name and MAC come from the same dhcpd.conf, next to the app."""
+
+    def test_guess_clone_name_and_mac_read_the_app_directory(self):
+        self.client.force_login(get_user_model().objects.create_superuser("dhcp_admin", "d@example.com", "pw"))
+        with tempfile.TemporaryDirectory() as tmp, override_settings(BASE_DIR=Path(tmp)):
+            Path(tmp, "dhcpd.conf").write_text(
+                "host clone7.example.com {\n  hardware ethernet 52:54:00:00:07:07;\n}\n"
+            )
+            with patch("instances.views.app_settings") as app_settings:
+                app_settings.CLONE_INSTANCE_DEFAULT_PREFIX = "clone"
+                response = self.client.get(reverse("instances:guess_clone_name"))
+            self.assertEqual(response.json(), {"name": "clone7"})
+            self.assertEqual(get_dhcp_mac_address("clone7"), "52:54:00:00:07:07")

instances/utils.py

@@ -231,8 +231,14 @@ def refr(compute):
     refresh_instance_database(compute)
 
 
+def dhcpd_conf():
+    """Optional dhcpd.conf in the application directory; clone names and MAC
+    addresses are taken from its host entries when it exists."""
+    return os.path.join(str(settings.BASE_DIR), "dhcpd.conf")
+
+
 def get_dhcp_mac_address(vname):
-    dhcp_file = str(settings.BASE_DIR) + "/dhcpd.conf"
+    dhcp_file = dhcpd_conf()
     mac = ""
     if os.path.isfile(dhcp_file):
         with open(dhcp_file, "r") as f:

instances/views.py

@@ -273,7 +273,7 @@ def random_mac_address(request):
 
 @superuser_only
 def guess_clone_name(request):
-    dhcp_file = "/srv/webvirtcloud/dhcpd.conf"
+    dhcp_file = utils.dhcpd_conf()
     prefix = app_settings.CLONE_INSTANCE_DEFAULT_PREFIX
     if os.path.isfile(dhcp_file):
         instance_names = [