fix(instances): every end of a migration job leaves a Logs row

Only migrate_instance, inside the job's run, wrote the migration's row:
a migration refused by precheck, cancelled while queued, or ended by
recovery after a worker restart left none. The job now has a log entry
for the ends migrate_instance did not log; run marks those it did.

instances/jobs.py

@@ -968,7 +968,6 @@ class MigrateInstance(Kind):
         ctx.record_intent()
         ctx.set_phase(gettext_noop("Migrating the VM"))
         try:
-            # migrate_instance logs the outcome
             utils.migrate_instance(Compute.objects.get(pk=p["target"]), instance, op.user,
                                    disk_pools=p["disk_pools"],
                                    **{k: p[k] for k in MIGRATE_OPTIONS})
@@ -982,8 +981,19 @@ class MigrateInstance(Kind):
             if isinstance(err, util.OperationError):
                 raise
             raise util.OperationError(str(err)) from err
+        finally:
+            # migrate_instance wrote the outcome's Logs row (log_entry)
+            ctx.record_intent(outcome_logged=True)
         return {}
 
+    def log_entry(self, op, state):
+        """A row for an end migrate_instance did not log: refused before it
+        ran, cancelled while queued, or ended by recovery."""
+        if op.intent.get("outcome_logged"):
+            return None
+        target = Compute.objects.filter(pk=op.params["target"]).values_list("name", flat=True).first()
+        return _log(op, state, f"migrate to {target}")
+
     def progress(self, op):
         info = _proxy(_instance(op.params["instance"])).instance.jobInfo()
         return (info[4], info[3]) if info[3] else None

instances/tests/test_migrate_job.py

@@ -213,3 +213,18 @@ class MigrateJobTestCase(TransactionTestCase):
             proxy.return_value.instance.isActive.return_value = False
             get_kind(op.kind).cancel(op)
         proxy.return_value.instance.abortJob.assert_not_called()
+
+    def test_each_end_of_a_migration_leaves_one_logs_row(self):
+        from logs.models import Logs
+
+        op = self.queue(live_migrate="true")
+        ctx = self.start(op)
+        get_kind(op.kind).run(op, ctx)  # migrate_instance writes its row
+        op.refresh_from_db()
+        self.assertIsNone(MigrateInstance().log_entry(op, Operation.SUCCEEDED))
+        self.assertEqual(Logs.objects.filter(instance_uuid=UUID).count(), 1)
+        # ended without migrate_instance: refused, cancelled while queued, or by recovery
+        queued = Operation(params={"instance": self.vm.pk, "target": self.dest.pk}, intent={"uuid": UUID},
+                           resource_label="mig-src/mig-vm")
+        self.assertEqual(MigrateInstance().log_entry(queued, Operation.CANCELLED),
+                         ("mig-src", "mig-vm", UUID, "VM mig-vm: migrate to mig-dst (cancelled)"))