Remove ram/disk sched filters from default list

Since we now use placement to verify basic CPU/RAM/disk resources,
we should default to disabling the equivalent scheduler filters.

Oddly enough, CoreFilter was already disabled so now also disable
RamFilter and DiskFilter.

Closes-Bug: #1709328
Change-Id: Ibe1cee1cb2642f61a8d6bf9c3f6bbee4f2c2f414

nova/conf/scheduler.py

@@ -248,8 +248,6 @@ Related options:
         default=[
           "RetryFilter",
           "AvailabilityZoneFilter",
-          "RamFilter",
-          "DiskFilter",
           "ComputeFilter",
           "ComputeCapabilitiesFilter",
           "ImagePropertiesFilter",
@@ -262,8 +260,7 @@ Related options:
 Filters that the scheduler will use.
 
 An ordered list of filter class names that will be used for filtering
-hosts. Ignore the word 'default' in the name of this option: these filters will
-*always* be applied, and they will be applied in the order they are listed so
+hosts. These filters will be applied in the order they are listed so
 place your most restrictive filters first to make the filtering process more
 efficient.
 

releasenotes/notes/trim-default-sched-filters-e70de3bb4c7b1a1b.yaml

@@ -0,0 +1,10 @@
+---
+upgrade:
+  - |
+    Since we now use Placement to verify basic CPU/RAM/disk resources when
+    using the FilterScheduler, the ``RamFilter`` and ``DiskFilter`` entries are
+    being removed from the default value for the ``enabled_filters`` config
+    option in the ``[filter_scheduler]`` group.  If you are overriding this
+    option, you probably should remove them from your version.  If you are
+    using CachingScheduler you may wish to enable these filters as we will
+    not use Placement in that case.