Refactor DriverBase.get_instance()

scope param is added to allow getting multiple independent instances
of a driver. This is particularly useful for using same VIFPoolDriver
implementation for multiple PodVIFDrivers (eg. NoopVIFPool may be
used for multiple PodVIFDriver types)

Also renames driver_alias to specific_driver to better indicate its
function.

Related-Bug: 1747406
Change-Id: Iea3b65b91f362a18cca6bf9d44d938063a56118b
Signed-off-by: Yash Gupta <y.gupta@samsung.com>

kuryr_kubernetes/controller/drivers/base.py

@@ -51,21 +51,36 @@ class DriverBase(object):
     """
 
     @classmethod
-    def get_instance(cls, driver_alias=None):
+    def get_instance(cls, specific_driver=None, scope='default'):
-        """Get an implementing driver instance."""
+        """Get an implementing driver instance.
+
+        :param specific_driver: Loads a specific driver instead of using conf.
+                                Uses separate manager entry so that loading of
+                                default/other drivers is not affected.
+        :param scope: Loads the driver in the given scope (if independent
+                      instances of a driver are required)
+        """
 
         alias = cls.ALIAS
-        driver_name = alias + '_driver' if not driver_alias else driver_alias
+
+        if specific_driver:
+            driver_key = '{}:{}:{}'.format(alias, specific_driver, scope)
+        else:
+            driver_key = '{}:_from_cfg:{}'.format(alias, scope)
+
         try:
-            manager = _DRIVER_MANAGERS[driver_name]
+            manager = _DRIVER_MANAGERS[driver_key]
         except KeyError:
-            name = (config.CONF.kubernetes[driver_name] if not driver_alias
+            if specific_driver:
-                    else driver_alias)
+                driver_name = specific_driver
+            else:
+                driver_name = config.CONF.kubernetes[alias + '_driver']
+
             manager = stv_driver.DriverManager(
                 namespace="%s.%s" % (_DRIVER_NAMESPACE_BASE, alias),
-                name=name,
+                name=driver_name,
                 invoke_on_load=True)
-            _DRIVER_MANAGERS[driver_name] = manager
+            _DRIVER_MANAGERS[driver_key] = manager
 
         driver = manager.driver
         if not isinstance(driver, cls):

kuryr_kubernetes/controller/drivers/multi_vif.py

@@ -35,7 +35,7 @@ class NPWGMultiVIFDriver(base.MultiVIFDriver):
     def __init__(self):
         super(NPWGMultiVIFDriver, self).__init__()
         self._drv_vif_pool = base.VIFPoolDriver.get_instance(
-            driver_alias='multi_pool')
+            specific_driver='multi_pool')
         self._drv_vif_pool.set_vif_driver()
 
     def request_additional_vifs(self, pod, project_id, security_groups):
@@ -71,7 +71,7 @@ class NPWGMultiVIFDriver(base.MultiVIFDriver):
             else:
                 alias = config[constants.K8S_ANNOTATION_NPWG_CRD_DRIVER_TYPE]
                 vif_drv = base.PodVIFDriver.get_instance(
-                    driver_alias=alias)
+                    specific_driver=alias)
             vif = vif_drv.request_vif(pod, project_id, subnet, security_groups)
             if vif:
                 vifs.append(vif)

kuryr_kubernetes/controller/drivers/vif_pool.py

@@ -774,9 +774,10 @@ class MultiVIFPool(base.VIFPoolDriver):
                 LOG.error("The pool and pod driver selected are not "
                           "compatible. They will be skipped")
                 raise exceptions.MultiPodDriverPoolConfigurationNotSupported()
-            drv_vif = base.PodVIFDriver.get_instance(driver_alias=pod_driver)
+            drv_vif = base.PodVIFDriver.get_instance(
+                specific_driver=pod_driver)
             drv_pool = base.VIFPoolDriver.get_instance(
-                driver_alias=pool_driver)
+                specific_driver=pool_driver)
             drv_pool.set_vif_driver(drv_vif)
             self._vif_drvs[pod_driver] = drv_pool
 

kuryr_kubernetes/controller/handlers/namespace.py

@@ -35,7 +35,7 @@ class NamespaceHandler(k8s_base.ResourceEventHandler):
         self._drv_subnets = drivers.PodSubnetsDriver.get_instance()
         self._drv_sg = drivers.PodSecurityGroupsDriver.get_instance()
         self._drv_vif_pool = drivers.VIFPoolDriver.get_instance(
-            driver_alias='multi_pool')
+            specific_driver='multi_pool')
         self._drv_vif_pool.set_vif_driver()
 
     def on_present(self, namespace):

kuryr_kubernetes/controller/handlers/vif.py

@@ -52,7 +52,7 @@ class VIFHandler(k8s_base.ResourceEventHandler):
         # VIFHandler driver, for now it is aware of the pool driver, but this
         # will be reverted as soon as a mechanism is in place.
         self._drv_vif_pool = drivers.VIFPoolDriver.get_instance(
-            driver_alias='multi_pool')
+            specific_driver='multi_pool')
         self._drv_vif_pool.set_vif_driver()
         self._drv_multi_vif = drivers.MultiVIFDriver.get_enabled_drivers()
 

kuryr_kubernetes/tests/unit/controller/drivers/test_base.py

@@ -51,6 +51,7 @@ class TestDriverBase(test_base.TestCase):
     def test_get_instance_not_loaded(self, m_stv_mgr, m_cfg, m_mgrs):
         alias = _TestDriver.ALIAS
         cfg_name = '%s_driver' % (alias)
+        mgr_key = '%s:_from_cfg:default' % (alias)
         drv_name = 'driver_impl'
         namespace = '%s.%s' % (d_base._DRIVER_NAMESPACE_BASE, alias)
         m_cfg.kubernetes.__getitem__.return_value = drv_name
@@ -64,7 +65,7 @@ class TestDriverBase(test_base.TestCase):
         m_cfg.kubernetes.__getitem__.assert_called_with(cfg_name)
         m_stv_mgr.assert_called_with(namespace=namespace, name=drv_name,
                                      invoke_on_load=True)
-        m_mgrs.__setitem__.assert_called_once_with(cfg_name, m_mgr)
+        m_mgrs.__setitem__.assert_called_once_with(mgr_key, m_mgr)
 
     @mock.patch.object(d_base, '_DRIVER_MANAGERS')
     @mock.patch('kuryr_kubernetes.config.CONF')

kuryr_kubernetes/tests/unit/controller/drivers/test_multi_vif.py

@@ -132,7 +132,7 @@ class TestNPWGMultiVIFDriver(test_base.TestCase):
         m_drv = multi_vif.NPWGMultiVIFDriver()
         self.assertEqual(self._vif_pool_drv, m_drv._drv_vif_pool)
         m_get_vif_pool_driver.assert_called_once_with(
-            driver_alias='multi_pool')
+            specific_driver='multi_pool')
         m_set_vifs_driver.assert_called_once()
 
     @mock.patch('kuryr_kubernetes.utils.get_subnet')