Merge ~adam-collard/maas:2.9-pod-hints-average into maas:2.9

[Adam Collard]

Change PodHints CPU speed to be mean-average of nodes'

Previous implementation seemed to be a naive implementation of an
average with "cpu_speed = (cpu_speed + node.cpu_speed) / 2" which
falls down with 3 or more nodes.

Cherry-pick 4ace066772f093d8b4b367d9becf43cde748825b

[Adam Collard (adam-collard)]

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b 2.9-pod-hints-average lp:~adam-collard/maas/+git/maas into -b 2.9 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/8812/consoleText

[MAAS Lander (maas-lander)]

LANDING
-b 2.9-pod-hints-average lp:~adam-collard/maas/+git/maas into -b 2.9 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/8815/consoleText

diff --git a/src/maasserver/models/bmc.py b/src/maasserver/models/bmc.py
index 5fe306b..95f3f1a 100644
--- a/src/maasserver/models/bmc.py
+++ b/src/maasserver/models/bmc.py
@@ -6,6 +6,7 @@
 
 from functools import partial
 import re
+from statistics import mean
 
 from django.contrib.postgres.fields import ArrayField, JSONField
 from django.core.exceptions import PermissionDenied, ValidationError
@@ -1548,7 +1549,7 @@ class Pod(BMC):
         podlog.info("%s: finished syncing discovered information" % self.name)
 
     def sync_hints_from_nodes(self):
-        """Sync the hints based on discovered data from assoicated nodes."""
+        """Sync the hints based on discovered data from associated nodes."""
         try:
             hints = self.hints
         except PodHints.DoesNotExist:
@@ -1558,6 +1559,7 @@ class Pod(BMC):
         self.memory = hints.memory = 0
         self.local_disks = hints.local_disks = 0
         self.iscsi_storage = hints.iscsi_storage = 0
+        cpu_speeds = []
         # Set the hints for the Pod to the total amount for all nodes in a
         # cluster.
         for node in hints.nodes.all().prefetch_related(
@@ -1569,11 +1571,7 @@ class Pod(BMC):
                 hints.memory += numa.memory
                 self.memory += numa.memory
             if node.cpu_speed != 0:
-                if hints.cpu_speed != 0:
-                    hints.cpu_speed = (hints.cpu_speed + node.cpu_speed) / 2
-                else:
-                    hints.cpu_speed = node.cpu_speed
-                self.cpu_speed = hints.cpu_speed
+                cpu_speeds.append(node.cpu_speed)
             for bd in node.blockdevice_set.all():
                 if bd.type == "physical":
                     hints.local_disks += 1
@@ -1581,6 +1579,9 @@ class Pod(BMC):
                 elif bd.type == "iscsi":
                     hints.iscsi_storage += bd.size
                     self.iscsi_storage += bd.size
+        self.cpu_speed = hints.cpu_speed = (
+            mean(cpu_speeds) if cpu_speeds else 0
+        )
         hints.save()
         self.save()
 
diff --git a/src/maasserver/models/tests/test_bmc.py b/src/maasserver/models/tests/test_bmc.py
index 249a093..76216e9 100644
--- a/src/maasserver/models/tests/test_bmc.py
+++ b/src/maasserver/models/tests/test_bmc.py
@@ -5,6 +5,7 @@
 
 
 import random
+from statistics import mean
 from unittest.mock import Mock, sentinel
 
 from crochet import wait_for
@@ -2475,7 +2476,7 @@ class TestPod(MAASServerTestCase):
         pod.sync_hints_from_nodes()
 
         cores = 0
-        cpu_speed = 0
+        cpu_speeds = []
         memory = 0
         local_storage = 0
         iscsi_storage = 0
@@ -2483,10 +2484,7 @@ class TestPod(MAASServerTestCase):
             for numa in node.numanode_set.all():
                 cores += len(numa.cores)
                 memory += numa.memory
-            if cpu_speed == 0:
-                cpu_speed = node.cpu_speed
-            else:
-                cpu_speed = (cpu_speed + node.cpu_speed) / 2
+            cpu_speeds.append(node.cpu_speed)
             for bd in node.blockdevice_set.all():
                 if bd.type == "physical":
                     local_storage += bd.size
@@ -2494,7 +2492,11 @@ class TestPod(MAASServerTestCase):
                     iscsi_storage += bd.size
 
         self.assertEquals(pod.hints.cores, cores)
-        self.assertEquals(pod.hints.cpu_speed, int(cpu_speed))
+        self.assertEquals(
+            pod.hints.cpu_speed,
+            int(mean(cpu_speeds)),
+            f"Wrong hint ({pod.hints.cpu_speed}) for CPU speed. CPU speeds of nodes: {cpu_speeds}",
+        )
         self.assertEquals(pod.hints.memory, memory)
         self.assertEquals(pod.hints.local_disks, len(nodes))
         self.assertEquals(pod.hints.iscsi_storage, iscsi_storage)
diff --git a/src/maasserver/triggers/tests/test_system_listener.py b/src/maasserver/triggers/tests/test_system_listener.py
index be1d117..1573f02 100644
--- a/src/maasserver/triggers/tests/test_system_listener.py
+++ b/src/maasserver/triggers/tests/test_system_listener.py
@@ -3834,7 +3834,9 @@ class TestDNSStaticIPAddressListener(
                 "ip": old_ip,
             },
         )
-        new_ip = factory.pick_ip_in_network(subnet.get_ipnetwork())
+        new_ip = factory.pick_ip_in_network(
+            subnet.get_ipnetwork(), but_not=[old_ip]
+        )
         yield self.capturePublication()
         dv = DeferredValue()
         listener = self.make_listener_without_delay()
@@ -3875,7 +3877,9 @@ class TestDNSStaticIPAddressListener(
                 "ip": old_ip,
             },
         )
-        new_ip = factory.pick_ip_in_network(subnet.get_ipnetwork())
+        new_ip = factory.pick_ip_in_network(
+            subnet.get_ipnetwork(), but_not=[old_ip]
+        )
         yield self.capturePublication()
         dv = DeferredValue()
         listener = self.make_listener_without_delay()