Move compute_driver into nova.virt.driver

Commit 9102f80 moved compute_driver from nova.compute.manager into
nova.config. We're trying to get away from so many global options,
so where to put it?

The config option is used for two things - loading the driver and,
in a bunch of random places, checking if it matches a specific
value.

It seems to make perfect to sense to encapsulate both as functions
in nova.virt.driver and move the option there.

blueprint: scope-config-opts
Change-Id: I28a71df5b682c6bd381401f63da49d91fb187125

nova/block_device.py

@@ -17,10 +17,7 @@
 
 import re
 
-from nova.openstack.common import cfg
-
-CONF = cfg.CONF
-CONF.import_opt('compute_driver', 'nova.config')
+from nova.virt import driver
 
 DEFAULT_ROOT_DEV_NAME = '/dev/sda1'
 _DEFAULT_MAPPINGS = {'ami': 'sda1',
@@ -95,7 +92,7 @@ def instance_block_mapping(instance, bdms):
     root_device_name = instance['root_device_name']
     # NOTE(clayg): remove this when xenapi is setting default_root_device
     if root_device_name is None:
-        if CONF.compute_driver.endswith('xenapi.XenAPIDriver'):
+        if driver.compute_driver_matches('xenapi.XenAPIDriver'):
             root_device_name = '/dev/xvda'
         else:
             return _DEFAULT_MAPPINGS

nova/compute/manager.py

@@ -29,8 +29,6 @@ terminating it.
 
 :instances_path:  Where instances are kept on disk
 :base_dir_name:  Where cached images are stored under instances_path
-:compute_driver:  Name of class that is used to handle virtualization, loaded
-                  by :func:`nova.openstack.common.importutils.import_object`
 
 """
 
@@ -177,7 +175,6 @@ CONF.register_opts(interval_opts)
 CONF.register_opts(timeout_opts)
 CONF.register_opts(running_deleted_opts)
 CONF.import_opt('allow_resize_to_same_host', 'nova.compute.api')
-CONF.import_opt('compute_driver', 'nova.config')
 CONF.import_opt('console_topic', 'nova.config')
 CONF.import_opt('host', 'nova.config')
 CONF.import_opt('my_ip', 'nova.config')
@@ -313,27 +310,8 @@ class ComputeManager(manager.SchedulerDependentManager):
 
     def __init__(self, compute_driver=None, *args, **kwargs):
         """Load configuration options and connect to the hypervisor."""
-        # TODO(vish): sync driver creation logic with the rest of the system
-        #             and re-document the module docstring
-        if not compute_driver:
-            compute_driver = CONF.compute_driver
-
-        if not compute_driver:
-            LOG.error(_("Compute driver option required, but not specified"))
-            sys.exit(1)
-
         self.virtapi = ComputeVirtAPI(self)
-
-        LOG.info(_("Loading compute driver '%s'") % compute_driver)
-        try:
-            self.driver = utils.check_isinstance(
-                    importutils.import_object_ns('nova.virt', compute_driver,
-                                                 self.virtapi),
-                    driver.ComputeDriver)
-        except ImportError as e:
-            LOG.error(_("Unable to load the virtualization driver: %s") % (e))
-            sys.exit(1)
-
+        self.driver = driver.load_compute_driver(self.virtapi, compute_driver)
         self.network_api = network.API()
         self.volume_api = volume.API()
         self.network_manager = importutils.import_object(

nova/compute/utils.py

@@ -30,9 +30,9 @@ from nova.openstack.common import cfg
 from nova.openstack.common import log
 from nova.openstack.common.notifier import api as notifier_api
 from nova import utils
+from nova.virt import driver
 
 CONF = cfg.CONF
-CONF.import_opt('compute_driver', 'nova.config')
 CONF.import_opt('host', 'nova.config')
 LOG = log.getLogger(__name__)
 
@@ -88,7 +88,7 @@ def get_device_name_for_instance(context, instance, device):
     except (TypeError, AttributeError, ValueError):
         raise exception.InvalidDevicePath(path=mappings['root'])
     # NOTE(vish): remove this when xenapi is setting default_root_device
-    if CONF.compute_driver.endswith('xenapi.XenAPIDriver'):
+    if driver.compute_driver_matches('xenapi.XenAPIDriver'):
         prefix = '/dev/xvd'
     if req_prefix != prefix:
         LOG.debug(_("Using %(prefix)s instead of %(req_prefix)s") % locals())
@@ -103,7 +103,7 @@ def get_device_name_for_instance(context, instance, device):
 
     # NOTE(vish): remove this when xenapi is properly setting
     #             default_ephemeral_device and default_swap_device
-    if CONF.compute_driver.endswith('xenapi.XenAPIDriver'):
+    if driver.compute_driver_matches('xenapi.XenAPIDriver'):
         instance_type_id = instance['instance_type_id']
         instance_type = instance_types.get_instance_type(instance_type_id)
         if instance_type['ephemeral_gb']:

nova/config.py

@@ -294,11 +294,6 @@ global_opts = [
     cfg.StrOpt('auth_strategy',
                default='noauth',
                help='The strategy to use for auth: noauth or keystone.'),
-    cfg.StrOpt('compute_driver',
-               help='Driver to use for controlling virtualization. Options '
-                   'include: libvirt.LibvirtDriver, xenapi.XenAPIDriver, '
-                   'fake.FakeDriver, baremetal.BareMetalDriver, '
-                   'vmwareapi.VMWareESXDriver'),
 ]
 
 cfg.CONF.register_opts(global_opts)

nova/tests/api/ec2/test_cinder_cloud.py

@@ -37,6 +37,7 @@ from nova.tests import matchers
 from nova import volume
 
 CONF = cfg.CONF
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 CONF.import_opt('default_instance_type', 'nova.config')
 CONF.import_opt('use_ipv6', 'nova.config')
 LOG = logging.getLogger(__name__)

nova/tests/api/ec2/test_cloud.py

@@ -49,6 +49,7 @@ from nova.virt import fake as fake_virt
 from nova import volume
 
 CONF = cfg.CONF
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 CONF.import_opt('default_image', 'nova.config')
 CONF.import_opt('default_instance_type', 'nova.config')
 CONF.import_opt('use_ipv6', 'nova.config')

nova/tests/api/ec2/test_ec2_validate.py

@@ -33,6 +33,7 @@ from nova.tests import fake_network
 from nova.tests.image import fake
 
 CONF = cfg.CONF
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 LOG = logging.getLogger(__name__)
 
 

nova/tests/compute/test_compute_utils.py

@@ -38,6 +38,7 @@ from nova import utils
 LOG = logging.getLogger(__name__)
 CONF = cfg.CONF
 CONF.import_opt('compute_manager', 'nova.config')
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 
 
 class ComputeValidateDeviceTestCase(test.TestCase):

nova/tests/compute/test_multiple_nodes.py

@@ -28,6 +28,7 @@ from nova.virt import fake
 
 CONF = cfg.CONF
 CONF.import_opt('compute_manager', 'nova.config')
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 
 
 class BaseTestCase(test.TestCase):

nova/tests/fake_flags.py

@@ -20,12 +20,12 @@ from nova.openstack.common import cfg
 
 CONF = cfg.CONF
 CONF.import_opt('state_path', 'nova.config')
-
 CONF.import_opt('scheduler_driver', 'nova.scheduler.manager')
 CONF.import_opt('fake_network', 'nova.network.manager')
 CONF.import_opt('network_size', 'nova.network.manager')
 CONF.import_opt('num_networks', 'nova.network.manager')
 CONF.import_opt('policy_file', 'nova.policy')
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 
 
 def set_defaults(conf):

nova/tests/test_notifications.py

@@ -26,12 +26,15 @@ from nova import context
 from nova import db
 from nova.network import api as network_api
 from nova import notifications
+from nova.openstack.common import cfg
 from nova.openstack.common import log as logging
 from nova.openstack.common.notifier import api as notifier_api
 from nova.openstack.common.notifier import test_notifier
 from nova import test
 from nova.tests import fake_network
 
+CONF = cfg.CONF
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 LOG = logging.getLogger(__name__)
 
 

nova/tests/test_quota.py

@@ -35,6 +35,7 @@ import nova.tests.image.fake
 
 CONF = cfg.CONF
 CONF.import_opt('scheduler_topic', 'nova.config')
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 
 
 class QuotaIntegrationTestCase(test.TestCase):

nova/tests/test_xenapi.py

@@ -58,6 +58,7 @@ LOG = logging.getLogger(__name__)
 
 CONF = cfg.CONF
 CONF.import_opt('compute_manager', 'nova.config')
+CONF.import_opt('compute_driver', 'nova.virt.driver')
 CONF.import_opt('host', 'nova.config')
 CONF.import_opt('network_manager', 'nova.config')
 CONF.import_opt('node_availability_zone', 'nova.config')

nova/virt/driver.py

@@ -22,8 +22,23 @@ Driver base-classes:
     types that support that contract
 """
 
-from nova.openstack.common import log as logging
+import sys
 
+from nova.openstack.common import cfg
+from nova.openstack.common import importutils
+from nova.openstack.common import log as logging
+from nova import utils
+
+driver_opts = [
+    cfg.StrOpt('compute_driver',
+               help='Driver to use for controlling virtualization. Options '
+                   'include: libvirt.LibvirtDriver, xenapi.XenAPIDriver, '
+                   'fake.FakeDriver, baremetal.BareMetalDriver, '
+                   'vmwareapi.VMWareESXDriver'),
+]
+
+CONF = cfg.CONF
+CONF.register_opts(driver_opts)
 LOG = logging.getLogger(__name__)
 
 
@@ -751,3 +766,39 @@ class ComputeDriver(object):
         if not isinstance(stats, list):
             stats = [stats]
         return [s['hypervisor_hostname'] for s in stats]
+
+
+def load_compute_driver(virtapi, compute_driver=None):
+    """Load a compute driver module.
+
+    Load the compute driver module specified by the compute_driver
+    configuration option or, if supplied, the driver name supplied as an
+    argument.
+
+    Compute drivers constructors take a VirtAPI object as their first object
+    and this must be supplied.
+
+    :param virtapi: a VirtAPI instance
+    :param compute_driver: a compute driver name to override the config opt
+    :returns: a ComputeDriver instance
+    """
+    if not compute_driver:
+        compute_driver = CONF.compute_driver
+
+    if not compute_driver:
+        LOG.error(_("Compute driver option required, but not specified"))
+        sys.exit(1)
+
+    LOG.info(_("Loading compute driver '%s'") % compute_driver)
+    try:
+        driver = importutils.import_object_ns('nova.virt',
+                                              compute_driver,
+                                              virtapi)
+        return utils.check_isinstance(driver, ComputeDriver)
+    except ImportError as e:
+        LOG.error(_("Unable to load the virtualization driver: %s") % (e))
+        sys.exit(1)
+
+
+def compute_driver_matches(match):
+    return CONF.compute_driver.endswith(match)