Merge "Deprecate RetryFilter"

doc/source/admin/configuration/schedulers.rst

@@ -18,14 +18,12 @@ Compute is configured with the following default scheduler options in the
 
    [filter_scheduler]
    available_filters = nova.scheduler.filters.all_filters
-   enabled_filters = RetryFilter, AvailabilityZoneFilter, ComputeFilter, ComputeCapabilitiesFilter, ImagePropertiesFilter, ServerGroupAntiAffinityFilter, ServerGroupAffinityFilter
+   enabled_filters = AvailabilityZoneFilter, ComputeFilter, ComputeCapabilitiesFilter, ImagePropertiesFilter, ServerGroupAntiAffinityFilter, ServerGroupAffinityFilter
 
 By default, the scheduler ``driver`` is configured as a filter scheduler, as
 described in the next section. In the default configuration, this scheduler
 considers hosts that meet all the following criteria:
 
-* Have not been attempted for scheduling purposes (``RetryFilter``).
-
 * Are in the requested availability zone (``AvailabilityZoneFilter``).
 
 * Can service the request (``ComputeFilter``).
@@ -720,13 +718,22 @@ free RAM.
 RetryFilter
 -----------
 
+.. deprecated:: 20.0.0
+
+   Since the 17.0.0 (Queens) release, the scheduler has provided alternate
+   hosts for rescheduling so the scheduler does not need to be called during
+   a reschedule which makes the ``RetryFilter`` useless. See the
+   `Return Alternate Hosts`_ spec for details.
+
 Filters out hosts that have already been attempted for scheduling purposes.  If
 the scheduler selects a host to respond to a service request, and the host
 fails to respond to the request, this filter prevents the scheduler from
 retrying that host for the service request.
 
-This filter is only useful if the ``scheduler_max_attempts`` configuration
-option is set to a value greater than zero.
+This filter is only useful if the :oslo.config:option:`scheduler.max_attempts`
+configuration option is set to a value greater than one.
+
+.. _Return Alternate Hosts: https://specs.openstack.org/openstack/nova-specs/specs/queens/implemented/return-alternate-hosts.html
 
 SameHostFilter
 --------------

doc/source/user/filter-scheduler.rst

@@ -167,8 +167,8 @@ There are many standard filter classes which may be used
   set of instances.
 * |SameHostFilter| - puts the instance on the same host as another instance in
   a set of instances.
-* |RetryFilter| - filters hosts that have been attempted for scheduling.
-  Only passes hosts that have not been previously attempted.
+* |RetryFilter| - DEPRECATED; filters hosts that have been attempted for
+  scheduling. Only passes hosts that have not been previously attempted.
 * |AggregateTypeAffinityFilter| - limits instance_type by aggregate.
    This filter passes hosts if no instance_type key is set or
    the instance_type aggregate metadata value contains the name of the
@@ -300,6 +300,15 @@ exception even if the problem is related to 1:N compute nodes. If you see that
 case in the scheduler logs, then your problem is most likely related to a
 compute problem and you should check the compute logs.
 
+.. note:: The ``RetryFilter`` is deprecated since the 20.0.0 (Train) release
+          and will be removed in an upcoming release. Since the 17.0.0 (Queens)
+          release, the scheduler has provided alternate hosts for rescheduling
+          so the scheduler does not need to be called during a reschedule which
+          makes the ``RetryFilter`` useless. See the `Return Alternate Hosts`_
+          spec for details.
+
+.. _Return Alternate Hosts: https://specs.openstack.org/openstack/nova-specs/specs/queens/implemented/return-alternate-hosts.html
+
 The |NUMATopologyFilter| considers the NUMA topology that was specified for the instance
 through the use of flavor extra_specs in combination with the image properties, as
 described in detail in the related nova-spec document:

nova/conf/scheduler.py

@@ -311,7 +311,6 @@ Related options:
         # Tempest's scheduler_enabled_filters to keep the default values in
         # sync.
         default=[
-          "RetryFilter",
           "AvailabilityZoneFilter",
           "ComputeFilter",
           "ComputeCapabilitiesFilter",

nova/scheduler/filters/retry_filter.py

@@ -29,6 +29,14 @@ class RetryFilter(filters.BaseHostFilter):
     # related to rebuild.
     RUN_ON_REBUILD = False
 
+    def __init__(self):
+        super(RetryFilter, self).__init__()
+        LOG.warning('The RetryFilter is deprecated since the 20.0.0 Train '
+                    'release. Since the 17.0.0 (Queens) release, the '
+                    'scheduler has provided alternate hosts for rescheduling '
+                    'so the scheduler does not need to be called during a '
+                    'reschedule which makes the RetryFilter useless.')
+
     def host_passes(self, host_state, spec_obj):
         """Skip nodes that have already been attempted."""
         retry = spec_obj.retry

nova/tests/unit/scheduler/filters/test_retry_filters.py

@@ -21,6 +21,8 @@ class TestRetryFilter(test.NoDBTestCase):
     def setUp(self):
         super(TestRetryFilter, self).setUp()
         self.filt_cls = retry_filter.RetryFilter()
+        self.assertIn('The RetryFilter is deprecated',
+                      self.stdlog.logger.output)
 
     def test_retry_filter_disabled(self):
         # Test case where retry/re-scheduling is disabled.

releasenotes/notes/deprecate-retry-filter-4d1dba39a2c21836.yaml

@@ -0,0 +1,10 @@
+---
+deprecations:
+  - |
+    The ``RetryFilter`` is deprecated and will be removed in an upcoming
+    release. Since the 17.0.0 (Queens) release, the scheduler has provided
+    alternate hosts for rescheduling so the scheduler does not need to be
+    called during a reschedule which makes the ``RetryFilter`` useless.
+    See the `Return Alternate Hosts`_ spec for details.
+
+    .. _Return Alternate Hosts: https://specs.openstack.org/openstack/nova-specs/specs/queens/implemented/return-alternate-hosts.html