conf: Attempt to resolve TODOs in scheduler.py

There are five options marked with TODOs:

* periodic_task_interval - negative values are valid, making the TODO
  invalid
* host_subset_size - code was in-place to prevent negative values, so
  replace this code with a min parameter
* isolated_images - removing this option requires a little bit of
  thought and would likely require a blueprint. Retain this for now.
* max_instances_per_host, attestation_auth_timeout,
  soft_affinity_weight_multiplier,
  soft_anti_affinity_weight_multiplier - support funky value ranges
  which, semantically speaking, shouldn't be allowed.  Start logging
  any "invalid" values.

Change-Id: I8871b628f0ab892830ceeede68db16948cb293c8

nova/conf/scheduler.py

@@ -99,7 +99,8 @@ be sure to test this with your selected scheduler.
 Possible values:
 
 * An integer, where the integer corresponds to periodic task interval in
-  seconds. A negative value disables periodic tasks.
+  seconds. 0 uses the default interval (60 seconds). A negative value disables
+  periodic tasks.
 
 Related options:
 
@@ -129,9 +130,9 @@ filter_scheduler_group = cfg.OptGroup(name="filter_scheduler",
                            title="Filter scheduler options")
 
 filter_scheduler_opts = [
-    # TODO(sfinucan): Add 'min' paramter
     cfg.IntOpt("host_subset_size",
         default=1,
+        min=1,
         deprecated_name="scheduler_host_subset_size",
         deprecated_group="DEFAULT",
         help="""

nova/scheduler/filter_scheduler.py

@@ -112,7 +112,7 @@ class FilterScheduler(driver.Scheduler):
 
             LOG.debug("Weighed %(hosts)s", {'hosts': weighed_hosts})
 
-            host_subset_size = max(1, CONF.filter_scheduler.host_subset_size)
+            host_subset_size = CONF.filter_scheduler.host_subset_size
             if host_subset_size < len(weighed_hosts):
                 weighed_hosts = weighed_hosts[0:host_subset_size]
             chosen_host = random.choice(weighed_hosts)

nova/scheduler/filters/num_instances_filter.py

@@ -53,6 +53,15 @@ class AggregateNumInstancesFilter(NumInstancesFilter):
 
     def _get_max_instances_per_host(self, host_state, spec_obj):
         max_instances_per_host = CONF.filter_scheduler.max_instances_per_host
+
+        # TODO(sfinucan): Remove this warning when the named config options
+        # gains a 'min' parameter.
+        if max_instances_per_host < 1:
+            LOG.warning(_LW('Future versions of nova will restrict the '
+                '"filter_scheduler.max_instances_per_host" config option to '
+                'values >=0. Update your configuration file to mitigate '
+                'future upgrade issues.'))
+
         aggregate_vals = utils.aggregate_values_from_key(
             host_state,
             'max_instances_per_host')

nova/scheduler/filters/trusted_filter.py

@@ -154,6 +154,14 @@ class ComputeAttestationCache(object):
             host = compute.hypervisor_hostname
             self._init_cache_entry(host)
 
+        # TODO(sfinucan): Remove this warning when the named config options
+        # gains a 'min' parameter.
+        if CONF.trusted_computing.attestation_auth_timeout < 0:
+            LOG.warning(_LW('Future versions of nova will restrict the '
+                '"trusted_computing.attestation_auth_timeout" config option '
+                'to values >=0. Update your configuration file to mitigate '
+                'future upgrade issues.'))
+
     def _cache_valid(self, host):
         cachevalid = False
         if host in self.compute_nodes:

nova/scheduler/weights/affinity.py

@@ -63,7 +63,10 @@ class ServerGroupSoftAffinityWeigher(_SoftAffinityWeigherBase):
             LOG.warning(_LW('For the soft_affinity_weight_multiplier only a '
                             'positive value is meaningful as a negative value '
                             'would mean that the affinity weigher would '
-                            'prefer non-collocating placement.'))
+                            'prefer non-collocating placement. Future '
+                            'versions of nova will restrict the config '
+                            'option to values >=0. Update your configuration '
+                            'file to mitigate future upgrade issues.'))
             self.warning_sent = True
 
         return CONF.filter_scheduler.soft_affinity_weight_multiplier
@@ -79,7 +82,11 @@ class ServerGroupSoftAntiAffinityWeigher(_SoftAffinityWeigherBase):
             LOG.warning(_LW('For the soft_anti_affinity_weight_multiplier '
                             'only a positive value is meaningful as a '
                             'negative value would mean that the anti-affinity '
-                            'weigher would prefer collocating placement.'))
+                            'weigher would prefer collocating placement. '
+                            'Future versions of nova will restrict the '
+                            'config option to values >=0. Update your '
+                            'configuration file to mitigate future upgrade '
+                            'issues.'))
             self.warning_sent = True
 
         return CONF.filter_scheduler.soft_anti_affinity_weight_multiplier