feat(logs): admin changes and logins are recorded on the Logs page

The Logs page shows who added, changed or deleted a compute, from web
or API, and every login, failed login, lockout and logout, with the
client address and a Result column (Done, Failed, Unknown for older
rows). A failed change is recorded with its reason and the error still
reaches the user; a refused one is recorded too.

- logs.audit.write saves each row in its own savepoint and never
  raises, so a log write cannot break or undo the action it records.
  The audit() context manager writes one row when the change ends.
- Logs gains success and ip; user, host and instance are wider and
  date is indexed. The page orders by date then id.
- A compute edit names the changed fields; an edit that changes
  nothing writes no row, and an empty password field is no change.
- A compute's VMs leaving the panel get a system row each: owners
  kept on the Removed VMs page, moved to another compute, restored,
  left without owners, or the removed record expired.
- Job rows carry the result. A job's log entry that cannot be
  computed is logged and skipped instead of rolling back the finish
  (test_service.py changes this on purpose).
- Logins are recorded by signal receivers; CustomLoginView is removed
  and the plain LoginView is used. A wrong OTP code is a failed login,
  counted by django-axes toward the lockout.

Panel records and host-side objects follow in the next layers.

computes/tests/test_audit_rows.py

@@ -0,0 +1,69 @@
+"""Adding, changing and deleting a compute, on the web and on the API, each write one audit row."""
+
+from django.contrib.auth import get_user_model
+from django.test import TestCase
+from django.urls import reverse
+from logs.models import Logs
+from operations import claims
+from operations.models import Claim
+from operations.utils import busy_message
+
+from computes.models import Compute
+
+
+class ComputeAuditRowTests(TestCase):
+    def setUp(self):
+        self.admin = get_user_model().objects.create_superuser("audit-admin", "audit@example.com", "pw")
+        self.client.force_login(self.admin)
+        Logs.objects.all().delete()  # the login's row
+
+    def messages(self):
+        return list(Logs.objects.order_by("id").values_list("message", flat=True))
+
+    def form_data(self, hostname):
+        return {"name": "c1", "hostname": hostname, "login": "admin", "password": "", "details": "", "type": 1}
+
+    def test_add_change_delete_write_rows(self):
+        self.client.post(reverse("add_tcp_host"), {**self.form_data("192.0.2.5"), "password": "secret"})
+        row = Logs.objects.get()
+        self.assertEqual(
+            (row.message, row.success, row.host, row.ip, row.user),
+            ("Compute c1 (192.0.2.5): add", True, "c1", "127.0.0.1", "audit-admin"),
+        )
+
+        compute = Compute.objects.get()
+        self.client.post(reverse("compute_update", args=[compute.id]), self.form_data("192.0.2.6"))
+        self.assertEqual(self.messages()[1], "Compute c1 (192.0.2.5): change hostname")
+
+        self.client.post(reverse("compute_delete", args=[compute.id]))
+        self.assertEqual(self.messages()[2], "Compute c1 (192.0.2.6): delete")
+        self.assertFalse(Compute.objects.exists())
+
+    def test_an_edit_that_changes_nothing_writes_nothing(self):
+        compute = Compute.objects.create(name="c1", hostname="192.0.2.5", login="admin", password="secret", type=1)
+        self.client.post(reverse("compute_update", args=[compute.id]), self.form_data("192.0.2.5"))
+        self.assertFalse(Logs.objects.exists())
+
+    def test_a_busy_delete_writes_a_failed_row(self):
+        compute = Compute.objects.create(name="c1", hostname="192.0.2.5", login="admin", password="secret", type=1)
+        busy = claims.Busy(None)
+        claims.admit({claims.compute_key(compute.id): Claim.SHARED}, holder="192.0.2.30:1:1")
+        self.client.post(reverse("compute_delete", args=[compute.id]))
+        row = Logs.objects.get()
+        self.assertEqual(row.message, f"Compute c1 (192.0.2.5): delete: {busy_message(busy, self.admin)}")
+        self.assertFalse(row.success)
+        self.assertTrue(Compute.objects.exists())
+
+    def test_the_api_writes_the_same_rows(self):
+        data = {"name": "c1", "hostname": "192.0.2.5", "login": "admin", "password": "secret", "type": 1}
+        res = self.client.post("/api/v1/computes/", data, content_type="application/json")
+        self.assertEqual(res.status_code, 201)
+        pk = res.json()["id"]
+        res = self.client.patch(f"/api/v1/computes/{pk}/", {"hostname": "192.0.2.6"}, content_type="application/json")
+        self.assertEqual(res.status_code, 200)
+        res = self.client.delete(f"/api/v1/computes/{pk}/")
+        self.assertEqual(res.status_code, 204)
+        self.assertEqual(
+            self.messages(),
+            ["Compute c1 (192.0.2.5): add", "Compute c1 (192.0.2.5): change hostname", "Compute c1 (192.0.2.6): delete"],
+        )

computes/tests/test_ownership.py

@@ -11,6 +11,7 @@ from django.test import TestCase, override_settings
 from django.urls import reverse
 from django.utils import timezone
 from instances.models import Instance, InstanceTombstone
+from logs.models import Logs
 from operations import claims
 from operations.models import Claim
 from rest_framework.test import APIClient
@@ -54,6 +55,9 @@ class OwnershipTestCase(TestCase):
         vm = Instance.objects.get(compute=compute, uuid=UUID)
         return vm.is_template, [(ui.user, ui.is_change, ui.is_delete, ui.is_vnc) for ui in vm.userinstance_set.all()]
 
+    def rows(self):
+        return list(Logs.objects.order_by("id").values_list("user", "host", "message"))
+
     def test_vm_that_disappears_and_returns_keeps_its_owners(self):
         self.owned_vm(self.host_a)
         refresh_instance_database(self.host_a)  # undefined for a while
@@ -64,6 +68,15 @@ class OwnershipTestCase(TestCase):
 
         self.assertEqual(self.ownership(self.host_a), (True, [(self.owner, True, False, True)]))
         self.assertFalse(InstanceTombstone.objects.exists())
+        self.assertEqual(self.rows(), [
+            ("-", "host-a", f"VM vm ({UUID}): owners kept on the Removed VMs page"),
+            ("-", "host-a", f"VM vm ({UUID}): owners restored"),
+        ])
+
+    def test_an_ownerless_vm_leaves_a_row(self):
+        Instance.objects.create(compute=self.host_a, name="vm", uuid=UUID)
+        refresh_instance_database(self.host_a)
+        self.assertEqual(self.rows(), [("-", "host-a", f"VM vm ({UUID}): left the panel (no owners)")])
 
     def test_move_seen_on_the_new_host_first(self):
         self.owned_vm(self.host_a)
@@ -75,6 +88,7 @@ class OwnershipTestCase(TestCase):
 
         self.assertEqual(self.ownership(self.host_b), (True, [(self.owner, True, False, True)]))
         self.assertFalse(Instance.objects.filter(compute=self.host_a).exists())
+        self.assertEqual(self.rows(), [("-", "host-a", f"VM vm ({UUID}): owners moved to host-b")])
 
     def test_move_seen_on_the_old_host_first(self):
         self.owned_vm(self.host_a)
@@ -105,6 +119,7 @@ class OwnershipTestCase(TestCase):
 
         self.assertEqual(self.ownership(self.host_a), (False, []))
         self.assertFalse(InstanceTombstone.objects.exists())
+        self.assertIn(("-", "-", f"VM vm ({UUID}): removed record expired"), self.rows())
 
     def test_deleted_users_are_skipped(self):
         self.owned_vm(self.host_a)
@@ -128,6 +143,11 @@ class OwnershipTestCase(TestCase):
         self.owned_vm(self.host_a)
         self.delete(self.host_a)
         self.assertEqual(InstanceTombstone.objects.get().owners[0]["user"], self.owner.id)
+        self.assertEqual(self.rows(), [
+            ("cd-admin", "-", "Login"),
+            ("-", "host-a", f"VM vm ({UUID}): owners kept on the Removed VMs page"),
+            ("cd-admin", "host-a", "Compute host-a (host-a.example): delete"),
+        ])
 
         again = self.compute("host-a-again")
         self.on(again, [("vm", UUID)])