ironic: partition compute services by conductor group

This uses ironic’s conductor group feature to limit the subset of nodes
which a nova-compute service will manage. This allows for partitioning
nova-compute services to a particular location (building, aisle, rack,
etc), and provides a way for operators to manage the failure domain of a
given nova-compute service.

This adds two config options to the [ironic] config group:
* partition_key: the key to match with the conductor_group property on
  ironic nodes to limit the subset of nodes which can be managed.
* peer_list: a list of other compute service hostnames which manage the
  same partition_key, used when building the hash ring.

Change-Id: I1b184ff37948dc403fe38874613cd4d870c644fd
Implements: blueprint ironic-conductor-groups

nova/conf/ironic.py

@@ -79,6 +79,28 @@ Related options:
         min=0,
         help='Timeout (seconds) to wait for node serial console state '
              'changed. Set to 0 to disable timeout.'),
+    cfg.StrOpt(
+        'partition_key',
+        default=None,
+        mutable=True,
+        max_length=255,
+        regex=r'^[a-zA-Z0-9_.-]*$',
+        help='Case-insensitive key to limit the set of nodes that may be '
+             'managed by this service to the set of nodes in Ironic which '
+             'have a matching conductor_group property. If unset, all '
+             'available nodes will be eligible to be managed by this '
+             'service. Note that setting this to the empty string (``""``) '
+             'will match the default conductor group, and is different than '
+             'leaving the option unset.'),
+    cfg.ListOpt(
+        'peer_list',
+        default=[],
+        mutable=True,
+        help='List of hostnames for other nova-compute services with the same '
+             'partition_key config value. Nodes matching the partition_key '
+             'value will be distributed between this service and the other '
+             'services specified here. If partition_key is unset, this option '
+             'is ignored.'),
 ]
 
 deprecated_opts = {

nova/exception.py

@@ -2314,6 +2314,11 @@ class VirtDriverNotReady(NovaException):
     msg_fmt = _("Virt driver is not ready.")
 
 
+class InvalidPeerList(NovaException):
+    msg_fmt = _("Configured nova-compute peer list for the ironic virt "
+                "driver is invalid on host %(host)s")
+
+
 class InstanceDiskMappingFailed(NovaException):
     msg_fmt = _("Failed to map boot disk of instance %(instance_name)s to "
                 "the management partition from any Virtual I/O Server.")

nova/tests/unit/virt/ironic/test_client_wrapper.py

@@ -81,12 +81,12 @@ class IronicClientWrapperTestCase(test.NoDBTestCase):
         # nova.utils.get_ksa_adapter().get_endpoint()
         self.get_ksa_adapter.assert_called_once_with(
             'baremetal', ksa_auth=self.get_auth_plugin.return_value,
-            ksa_session='session', min_version=(1, 38),
+            ksa_session='session', min_version=(1, 46),
             max_version=(1, ksa_disc.LATEST))
         expected = {'session': 'session',
             'max_retries': CONF.ironic.api_max_retries,
             'retry_interval': CONF.ironic.api_retry_interval,
-            'os_ironic_api_version': ['1.38', '1.37'],
+            'os_ironic_api_version': ['1.46', '1.37'],
             'endpoint':
                 self.get_ksa_adapter.return_value.get_endpoint.return_value}
         mock_ir_cli.assert_called_once_with(1, **expected)
@@ -106,13 +106,13 @@ class IronicClientWrapperTestCase(test.NoDBTestCase):
         # nova.utils.get_endpoint_data
         self.get_ksa_adapter.assert_called_once_with(
             'baremetal', ksa_auth=self.get_auth_plugin.return_value,
-            ksa_session='session', min_version=(1, 38),
+            ksa_session='session', min_version=(1, 46),
             max_version=(1, ksa_disc.LATEST))
         # When get_endpoint_data raises any ServiceNotFound, None is returned.
         expected = {'session': 'session',
                     'max_retries': CONF.ironic.api_max_retries,
                     'retry_interval': CONF.ironic.api_retry_interval,
-                    'os_ironic_api_version': ['1.38', '1.37'],
+                    'os_ironic_api_version': ['1.46', '1.37'],
                     'endpoint': None}
         mock_ir_cli.assert_called_once_with(1, **expected)
 
@@ -130,7 +130,7 @@ class IronicClientWrapperTestCase(test.NoDBTestCase):
         expected = {'session': 'session',
                     'max_retries': CONF.ironic.api_max_retries,
                     'retry_interval': CONF.ironic.api_retry_interval,
-                    'os_ironic_api_version': ['1.38', '1.37'],
+                    'os_ironic_api_version': ['1.46', '1.37'],
                     'endpoint': endpoint}
         mock_ir_cli.assert_called_once_with(1, **expected)
 

nova/tests/unit/virt/ironic/test_driver.py

@@ -3254,9 +3254,11 @@ class HashRingTestCase(test.NoDBTestCase):
     @mock.patch.object(hash_ring, 'HashRing')
     @mock.patch.object(objects.ServiceList, 'get_all_computes_by_hv_type')
     def _test__refresh_hash_ring(self, services, expected_hosts, mock_services,
-                                 mock_hash_ring):
+                                 mock_hash_ring, uncalled=None):
+        uncalled = uncalled or []
         services = [_make_compute_service(host) for host in services]
-        is_up_calls = [mock.call(svc) for svc in services]
+        is_up_calls = [mock.call(svc) for svc in services
+                       if svc.host not in uncalled]
         self.flags(host='host1')
         mock_services.return_value = services
         mock_hash_ring.return_value = SENTINEL
@@ -3299,6 +3301,66 @@ class HashRingTestCase(test.NoDBTestCase):
         self.mock_is_up.side_effect = [True, True, False, True]
         self._test__refresh_hash_ring(services, expected_hosts)
 
+    @mock.patch.object(ironic_driver.IronicDriver, '_can_send_version')
+    def test__refresh_hash_ring_peer_list(self, mock_can_send):
+        services = ['host1', 'host2', 'host3']
+        expected_hosts = {'host1', 'host2'}
+        self.mock_is_up.return_value = True
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=['host1', 'host2'], group='ironic')
+        self._test__refresh_hash_ring(services, expected_hosts,
+                                      uncalled=['host3'])
+        mock_can_send.assert_called_once_with(min_version='1.46')
+
+    @mock.patch.object(ironic_driver.IronicDriver, '_can_send_version')
+    def test__refresh_hash_ring_peer_list_old_api(self, mock_can_send):
+        mock_can_send.side_effect = (
+            exception.IronicAPIVersionNotAvailable(version='1.46'))
+        services = ['host1', 'host2', 'host3']
+        expected_hosts = {'host1', 'host2', 'host3'}
+        self.mock_is_up.return_value = True
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=['host1', 'host2'], group='ironic')
+        self._test__refresh_hash_ring(services, expected_hosts,
+                                      uncalled=['host3'])
+        mock_can_send.assert_called_once_with(min_version='1.46')
+
+    @mock.patch.object(ironic_driver, 'LOG', autospec=True)
+    def test__check_peer_list(self, mock_log):
+        self.flags(host='host1')
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=['host1', 'host2'], group='ironic')
+        ironic_driver._check_peer_list()
+        # happy path, nothing happens
+        self.assertFalse(mock_log.error.called)
+        self.assertFalse(mock_log.warning.called)
+
+    @mock.patch.object(ironic_driver, 'LOG', autospec=True)
+    def test__check_peer_list_empty(self, mock_log):
+        self.flags(host='host1')
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=[], group='ironic')
+        self.assertRaises(exception.InvalidPeerList,
+                          ironic_driver._check_peer_list)
+        self.assertTrue(mock_log.error.called)
+
+    @mock.patch.object(ironic_driver, 'LOG', autospec=True)
+    def test__check_peer_list_missing_self(self, mock_log):
+        self.flags(host='host1')
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=['host2'], group='ironic')
+        self.assertRaises(exception.InvalidPeerList,
+                          ironic_driver._check_peer_list)
+        self.assertTrue(mock_log.error.called)
+
+    @mock.patch.object(ironic_driver, 'LOG', autospec=True)
+    def test__check_peer_list_only_self(self, mock_log):
+        self.flags(host='host1')
+        self.flags(partition_key='not-none', group='ironic')
+        self.flags(peer_list=['host1'], group='ironic')
+        ironic_driver._check_peer_list()
+        self.assertTrue(mock_log.warning.called)
+
 
 class NodeCacheTestCase(test.NoDBTestCase):
 
@@ -3314,24 +3376,34 @@ class NodeCacheTestCase(test.NoDBTestCase):
         self.host = 'host1'
         self.flags(host=self.host)
 
+    @mock.patch.object(ironic_driver.IronicDriver, '_can_send_version')
     @mock.patch.object(ironic_driver.IronicDriver, '_refresh_hash_ring')
     @mock.patch.object(hash_ring.HashRing, 'get_nodes')
     @mock.patch.object(ironic_driver.IronicDriver, '_get_node_list')
     @mock.patch.object(objects.InstanceList, 'get_uuids_by_host')
     def _test__refresh_cache(self, instances, nodes, hosts, mock_instances,
-                             mock_nodes, mock_hosts, mock_hash_ring):
+                             mock_nodes, mock_hosts, mock_hash_ring,
+                             mock_can_send, partition_key=None,
+                             can_send_146=True):
         mock_instances.return_value = instances
         mock_nodes.return_value = nodes
         mock_hosts.side_effect = hosts
+        if not can_send_146:
+            mock_can_send.side_effect = (
+                exception.IronicAPIVersionNotAvailable(version='1.46'))
         self.driver.node_cache = {}
         self.driver.node_cache_time = None
 
+        kwargs = {}
+        if partition_key is not None and can_send_146:
+            kwargs['conductor_group'] = partition_key
+
         self.driver._refresh_cache()
 
         mock_hash_ring.assert_called_once_with(mock.ANY)
         mock_instances.assert_called_once_with(mock.ANY, self.host)
         mock_nodes.assert_called_once_with(fields=ironic_driver._NODE_FIELDS,
-                                           limit=0)
+                                           limit=0, **kwargs)
         self.assertIsNotNone(self.driver.node_cache_time)
 
     def test__refresh_cache(self):
@@ -3352,6 +3424,49 @@ class NodeCacheTestCase(test.NoDBTestCase):
         expected_cache = {n.uuid: n for n in nodes}
         self.assertEqual(expected_cache, self.driver.node_cache)
 
+    def test__refresh_cache_partition_key(self):
+        # normal operation, one compute service
+        instances = []
+        nodes = [
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+        ]
+        hosts = [self.host, self.host, self.host]
+        partition_key = 'some-group'
+        self.flags(partition_key=partition_key, group='ironic')
+
+        self._test__refresh_cache(instances, nodes, hosts,
+                                  partition_key=partition_key)
+
+        expected_cache = {n.uuid: n for n in nodes}
+        self.assertEqual(expected_cache, self.driver.node_cache)
+
+    def test__refresh_cache_partition_key_old_api(self):
+        # normal operation, one compute service
+        instances = []
+        nodes = [
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+            _get_cached_node(
+                uuid=uuidutils.generate_uuid(), instance_uuid=None),
+        ]
+        hosts = [self.host, self.host, self.host]
+        partition_key = 'some-group'
+        self.flags(partition_key=partition_key, group='ironic')
+
+        self._test__refresh_cache(instances, nodes, hosts,
+                                  partition_key=partition_key,
+                                  can_send_146=False)
+
+        expected_cache = {n.uuid: n for n in nodes}
+        self.assertEqual(expected_cache, self.driver.node_cache)
+
     def test__refresh_cache_multiple_services(self):
         # normal operation, many compute services
         instances = []

nova/virt/ironic/client_wrapper.py

@@ -32,7 +32,7 @@ ironic = None
 IRONIC_GROUP = nova.conf.ironic.ironic_group
 
 # The API version required by the Ironic driver
-IRONIC_API_VERSION = (1, 38)
+IRONIC_API_VERSION = (1, 46)
 # NOTE(TheJulia): This version should ALWAYS be the _last_ release
 # supported version of the API version used by nova. If a feature
 # needs 1.38 to be negotiated to operate properly, then the version

nova/virt/ironic/driver.py

@@ -131,6 +131,27 @@ def _log_ironic_polling(what, node, instance):
               instance=instance)
 
 
+def _check_peer_list():
+    # these configs are mutable; need to check at runtime and init
+    if CONF.ironic.partition_key is not None:
+        peer_list = set(CONF.ironic.peer_list)
+        if not peer_list:
+            LOG.error('FATAL: Peer list is not configured in the '
+                      '[ironic]/peer_list option; cannot map '
+                      'ironic nodes to compute services.')
+            raise exception.InvalidPeerList(host=CONF.host)
+        if CONF.host not in peer_list:
+            LOG.error('FATAL: Peer list does not contain this '
+                      'compute service hostname (%s); add it to '
+                      'the [ironic]/peer_list option.', CONF.host)
+            raise exception.InvalidPeerList(host=CONF.host)
+        if set([CONF.host]) == peer_list:
+            LOG.warning('This compute service (%s) is the only service '
+                        'present in the [ironic]/peer_list option. '
+                        'Are you sure this should not include more '
+                        'hosts?', CONF.host)
+
+
 class IronicDriver(virt_driver.ComputeDriver):
     """Hypervisor driver for Ironic - bare metal provisioning."""
 
@@ -667,10 +688,37 @@ class IronicDriver(virt_driver.ComputeDriver):
             return False
 
     def _refresh_hash_ring(self, ctxt):
+        peer_list = None
+        # NOTE(jroll) if this is set, we need to limit the set of other
+        # compute services in the hash ring to hosts that are currently up
+        # and specified in the peer_list config option, as there's no way
+        # to check which partition_key other compute services are using.
+        if CONF.ironic.partition_key is not None:
+            try:
+                # NOTE(jroll) first we need to make sure the Ironic API can
+                # filter by conductor_group. If it cannot, limiting to
+                # peer_list could end up with a node being managed by multiple
+                # compute services.
+                self._can_send_version(min_version='1.46')
+
+                peer_list = set(CONF.ironic.peer_list)
+                # these configs are mutable; need to check at runtime and init.
+                # luckily, we run this method from init_host.
+                _check_peer_list()
+                LOG.debug('Limiting peer list to %s', peer_list)
+            except exception.IronicAPIVersionNotAvailable:
+                pass
+
+        # TODO(jroll) optimize this to limit to the peer_list
         service_list = objects.ServiceList.get_all_computes_by_hv_type(
             ctxt, self._get_hypervisor_type())
         services = set()
         for svc in service_list:
+            # NOTE(jroll) if peer_list is None, we aren't partitioning by
+            # conductor group, so we check all compute services for liveness.
+            # if we have a peer_list, don't check liveness for compute
+            # services that aren't in the list.
+            if peer_list is None or svc.host in peer_list:
                 is_up = self.servicegroup_api.service_is_up(svc)
                 if is_up:
                     services.add(svc.host)
@@ -690,7 +738,31 @@ class IronicDriver(virt_driver.ComputeDriver):
         instances = objects.InstanceList.get_uuids_by_host(ctxt, CONF.host)
         node_cache = {}
 
-        for node in self._get_node_list(fields=_NODE_FIELDS, limit=0):
+        def _get_node_list(**kwargs):
+            return self._get_node_list(fields=_NODE_FIELDS, limit=0, **kwargs)
+
+        # NOTE(jroll) if partition_key is set, we need to limit nodes that
+        # can be managed to nodes that have a matching conductor_group
+        # attribute. If the API isn't new enough to support conductor groups,
+        # we fall back to managing all nodes. If it is new enough, we can
+        # filter it in the API.
+        partition_key = CONF.ironic.partition_key
+        if partition_key is not None:
+            try:
+                self._can_send_version(min_version='1.46')
+                nodes = _get_node_list(conductor_group=partition_key)
+                LOG.debug('Limiting manageable ironic nodes to conductor '
+                          'group %s', partition_key)
+            except exception.IronicAPIVersionNotAvailable:
+                LOG.error('Required Ironic API version 1.46 is not '
+                          'available to filter nodes by conductor group. '
+                          'All nodes will be eligible to be managed by '
+                          'this compute service.')
+                nodes = _get_node_list()
+        else:
+            nodes = _get_node_list()
+
+        for node in nodes:
             # NOTE(jroll): we always manage the nodes for instances we manage
             if node.instance_uuid in instances:
                 node_cache[node.uuid] = node

releasenotes/notes/ironic-partition-compute-nodes-fc60a6557fae9c5e.yaml

@@ -0,0 +1,12 @@
+---
+features:
+  - |
+    In deployments with Ironic, adds the ability for compute services to manage
+    a subset of Ironic nodes. If the ``[ironic]/partition_key`` configuration
+    option is set, the compute service will only consider nodes with a matching
+    ``conductor_group`` attribute for management. Setting the
+    ``[ironic]/peer_list`` configuration option allows this subset of nodes to
+    be distributed among the compute services specified to further reduce
+    failure domain. This feature is useful to co-locate nova-compute services
+    with ironic-conductor services managing the same nodes, or to better
+    control failure domain of a given compute service.