Merge ~ack/maas:1947087-vm-host-api-fix-used-counts into maas:master

[Alberto Donato]

LP:1947087 fix query to get used vmhost resources for the API

The previous aggregation was counting memory and cores multiple times if VMs
had more than one disk because of the join with the VirtualMachineDisk table.

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1947087-vm-host-api-fix-used-counts lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: aaed0938fbdbc635d3c1ff4791cb57b672ff7fd4

review: Approve

[Christian Grabowski (cgrabowski)]

+1

review: Approve

diff --git a/src/maasserver/models/tests/test_virtualmachine.py b/src/maasserver/models/tests/test_virtualmachine.py
index 02f3c75..d6654aa 100644
--- a/src/maasserver/models/tests/test_virtualmachine.py
+++ b/src/maasserver/models/tests/test_virtualmachine.py
@@ -807,3 +807,36 @@ class TestGetVMHostUsedResources(MAASServerTestCase):
         self.assertEqual(used_resources.memory, 0)
         self.assertEqual(used_resources.hugepages_memory, 0)
         self.assertEqual(used_resources.storage, 0)
+
+    def test_get_used_resources_multiple_disks(self):
+        project = factory.make_string()
+        vmhost = factory.make_Pod(
+            pod_type="lxd",
+            parameters={"project": project},
+        )
+        pool1 = factory.make_PodStoragePool(pod=vmhost)
+        pool2 = factory.make_PodStoragePool(pod=vmhost)
+        vm1 = factory.make_VirtualMachine(
+            bmc=vmhost,
+            project=project,
+            memory=1024,
+            pinned_cores=[0, 1, 2],
+            hugepages_backed=False,
+        )
+        factory.make_VirtualMachineDisk(vm=vm1, backing_pool=pool1, size=1000)
+        factory.make_VirtualMachineDisk(vm=vm1, backing_pool=pool2, size=2000)
+        vm2 = factory.make_VirtualMachine(
+            bmc=vmhost,
+            project=project,
+            memory=2048,
+            unpinned_cores=2,
+            hugepages_backed=True,
+        )
+        factory.make_VirtualMachineDisk(vm=vm2, backing_pool=pool1, size=1000)
+        factory.make_VirtualMachineDisk(vm=vm2, backing_pool=pool2, size=4000)
+        used_resources = get_vm_host_used_resources(vmhost)
+        self.assertEqual(used_resources.cores, 5)
+        self.assertEqual(used_resources.memory, 1024)
+        self.assertEqual(used_resources.hugepages_memory, 2048)
+        self.assertEqual(used_resources.total_memory, 3072)
+        self.assertEqual(used_resources.storage, 8000)
diff --git a/src/maasserver/models/virtualmachine.py b/src/maasserver/models/virtualmachine.py
index 07a2462..49082cc 100644
--- a/src/maasserver/models/virtualmachine.py
+++ b/src/maasserver/models/virtualmachine.py
@@ -300,10 +300,16 @@ def get_vm_host_used_resources(vmhost) -> VMHostUsedResources:
     counts = VirtualMachine.objects.filter(
         bmc=vmhost, project=vmhost.tracked_project
     ).aggregate(
-        cores=C(Sum("unpinned_cores") + Sum(ArrayLength("pinned_cores"))),
+        cores=C(Sum(F("unpinned_cores") + ArrayLength("pinned_cores"))),
         memory=C(Sum("memory", filter=Q(hugepages_backed=False))),
         hugepages_memory=C(Sum("memory", filter=Q(hugepages_backed=True))),
-        storage=C(Sum("disks_set__size")),
+    )
+    counts.update(
+        VirtualMachineDisk.objects.filter(
+            vm__bmc=vmhost, vm__project=vmhost.tracked_project
+        ).aggregate(
+            storage=C(Sum("size")),
+        )
     )
     return VMHostUsedResources(**counts)