Add option to force hosts to scheduler

Change-Id: I7364115e247ebeb441fa838ac66db5ef5f608b55

nova/compute/api.py

@@ -284,6 +284,20 @@ def _create_instance(self, context, instance_type,
         root_device_name = block_device.properties_root_device_name(
             image['properties'])
 
+        # NOTE(vish): We have a legacy hack to allow admins to specify hosts
+        #             via az using az:host. It might be nice to expose an
+        #             api to specify specific hosts to force onto, but for
+        #             now it just supports this legacy hack.
+        host = None
+        if availability_zone:
+            availability_zone, _x, host = availability_zone.partition(':')
+        if not availability_zone:
+            availability_zone = FLAGS.default_schedule_zone
+        if context.is_admin and host:
+            filter_properties = {'force_hosts': [host]}
+        else:
+            filter_properties = {}
+
         base_options = {
             'reservation_id': reservation_id,
             'image_ref': image_href,
@@ -343,7 +357,8 @@ def _create_instance(self, context, instance_type,
                 availability_zone, injected_files,
                 admin_password, image,
                 num_instances, requested_networks,
-                block_device_mapping, security_group)
+                block_device_mapping, security_group,
+                filter_properties)
 
         if create_instance_here:
             return ([instance], reservation_id)
@@ -516,7 +531,8 @@ def _schedule_run_instance(self,
             num_instances,
             requested_networks,
             block_device_mapping,
-            security_group):
+            security_group,
+            filter_properties):
         """Send a run_instance request to the schedulers for processing."""
 
         pid = context.project_id
@@ -525,8 +541,6 @@ def _schedule_run_instance(self,
         LOG.debug(_("Sending create to scheduler for %(pid)s/%(uid)s's") %
                 locals())
 
-        filter_properties = {}
-
         request_spec = {
             'image': image,
             'instance_properties': base_options,

nova/flags.py

@@ -467,3 +467,5 @@ def _get_my_ip():
 
 DEFINE_integer('service_down_time', 60,
         'maximum time since last check-in for up service')
+DEFINE_string('default_schedule_zone', None,
+              'zone to use when user doesnt specify one')

nova/scheduler/host_manager.py

@@ -117,6 +117,9 @@ def passes_filters(self, filter_fns, filter_properties):
 
         if self.host in filter_properties.get('ignore_hosts', []):
             return False
+        force_hosts = filter_properties.get('force_hosts', [])
+        if force_hosts:
+            return self.host in force_hosts
         for filter_fn in filter_fns:
             if not filter_fn(self, filter_properties):
                 return False

nova/scheduler/simple.py

@@ -35,8 +35,6 @@
                      "maximum number of volume gigabytes to allow per host")
 flags.DEFINE_integer("max_networks", 1000,
                      "maximum number of networks to allow per host")
-flags.DEFINE_string('default_schedule_zone', None,
-                    'zone to use when user doesnt specify one')
 flags.DEFINE_list('isolated_images', [], 'Images to run on isolated host')
 flags.DEFINE_list('isolated_hosts', [], 'Host reserved for specific images')
 flags.DEFINE_boolean('skip_isolated_core_check', True,

nova/tests/scheduler/test_host_manager.py

@@ -18,8 +18,6 @@
 
 import datetime
 
-import mox
-
 from nova import db
 from nova import exception
 from nova import log as logging
@@ -364,3 +362,21 @@ def test_host_state_passes_filters_fails_from_ignore(self):
         result = fake_host.passes_filters(filter_fns, filter_properties)
         self.mox.VerifyAll()
         self.assertFalse(result)
+
+    def test_host_state_passes_filters_skipped_from_force(self):
+        fake_host = host_manager.HostState('host1', 'compute')
+        filter_properties = {'force_hosts': ['host1']}
+
+        cls1 = ComputeFilterClass1()
+        cls2 = ComputeFilterClass2()
+        self.mox.StubOutWithMock(cls1, 'host_passes')
+        self.mox.StubOutWithMock(cls2, 'host_passes')
+        filter_fns = [cls1.host_passes, cls2.host_passes]
+
+        # cls[12].host_passes() not called because of short circuit
+        # with matching host to force
+
+        self.mox.ReplayAll()
+        result = fake_host.passes_filters(filter_fns, filter_properties)
+        self.mox.VerifyAll()
+        self.assertTrue(result)