Replace custom lazy loading by stevedore

Change-Id: I0b09e8822af6e8c3ce7299d31eb53f30a50262bc

ironic/common/utils.py

@@ -145,41 +145,6 @@ def random_alnum(size=32):
     return ''.join(random.choice(characters) for _ in range(size))
 
 
-class LazyPluggable(object):
-    """A pluggable backend loaded lazily based on some value."""
-
-    def __init__(self, pivot, config_group=None, **backends):
-        self.__backends = backends
-        self.__pivot = pivot
-        self.__backend = None
-        self.__config_group = config_group
-
-    def __get_backend(self):
-        if not self.__backend:
-            if self.__config_group is None:
-                backend_name = CONF[self.__pivot]
-            else:
-                backend_name = CONF[self.__config_group][self.__pivot]
-            if backend_name not in self.__backends:
-                msg = _('Invalid backend: %s') % backend_name
-                raise exception.IronicException(msg)
-
-            backend = self.__backends[backend_name]
-            if isinstance(backend, tuple):
-                name = backend[0]
-                fromlist = backend[1]
-            else:
-                name = backend
-                fromlist = backend
-
-            self.__backend = __import__(name, None, None, fromlist)
-        return self.__backend
-
-    def __getattr__(self, key):
-        backend = self.__get_backend()
-        return getattr(backend, key)
-
-
 def delete_if_exists(pathname):
     """delete a file, but ignore file not found error."""
 

setup.cfg

@@ -60,6 +60,9 @@ ironic.drivers =
     pxe_drac = ironic.drivers.drac:PXEDracDriver
     pxe_snmp = ironic.drivers.pxe:PXEAndSNMPDriver
 
+ironic.database.migration_backend =
+    sqlalchemy = ironic.db.sqlalchemy.migration
+
 [pbr]
 autodoc_index_modules = True