Dynamically load services

Change-Id: I3af2dc14bf15e172c6b10d6b5bbd96edf5baf8e3
Closes-Bug: 1420931

examples/common.py

@@ -119,6 +119,9 @@ class ProfileAction(argparse.Action):
 
     @classmethod
     def set_option(cls, var, values):
+        if var == '--os-extensions':
+            cls.prof.load_extension(values)
+            return
         if var == 'OS_REGION_NAME':
             var = 'region'
         var = var.replace('--os-api-', '')
@@ -246,6 +249,15 @@ def option_parser():
         default=env('OS_ACCESS_INFO'),
         help='Access info (Env: OS_ACCESS_INFO)',
     )
+    parser.add_argument(
+        '--os-extensions',
+        dest='user_preferences',
+        metavar='<namespace>',
+        action=ProfileAction,
+        default=ProfileAction.env('OS_EXTENSIONS'),
+        help='Entry point for namespace for service extensions'
+             ' env[OS_EXTENSIONS]',
+    )
     parser.add_argument(
         '--os-api-name',
         dest='preferences',

openstack/module_loader.py

@@ -18,6 +18,19 @@ from stevedore import extension
 from openstack import exceptions
 
 
+def load_service_extensions(namespace):
+    service_extensions = extension.ExtensionManager(
+        namespace=namespace,
+        invoke_on_load=True,
+    )
+    services = {}
+    for service in service_extensions:
+        service = service.obj
+        service.set_visibility(None)
+        services[service.service_type] = service
+    return services
+
+
 class ModuleLoader(object):
 
     def __init__(self):

openstack/profile.py

@@ -51,6 +51,7 @@ The resulting preference print out would look something like::
     service_type=identity,region=zion,version=v3
 """
 
+import logging
 import six
 
 from openstack.block_store import block_store_service
@@ -63,19 +64,24 @@ from openstack.image import image_service
 from openstack.key_management import key_management_service
 from openstack.message import message_service
 from openstack.metric import metric_service
+from openstack import module_loader
 from openstack.network import network_service
 from openstack.object_store import object_store_service
 from openstack.orchestration import orchestration_service
 from openstack.telemetry import telemetry_service
 
+_logger = logging.getLogger(__name__)
+
 
 class Profile(object):
 
     ALL = "*"
     """Wildcard service identifier representing all services."""
 
-    def __init__(self):
-        """Preferences for each service.
+    def __init__(self, extensions=None):
+        """User preference for each service.
+
+        :param list extensions: List of entry point namespace to load.
 
         Create a new :class:`~openstack.profile.Profile`
         object with no preferences defined, but knowledge of the services.
@@ -129,11 +135,27 @@ class Profile(object):
         serv.set_visibility(None)
         self._services[serv.service_type] = serv
 
+        if extensions:
+            for extension in extensions:
+                self.load_extension(extension)
         self.service_names = sorted(self._services.keys())
 
     def __repr__(self):
         return repr(self._preferences)
 
+    def load_extension(self, namespace):
+        """Load a service extension.
+
+        :param str namespace: Entry point namespace
+        """
+        services = module_loader.load_service_extensions(namespace)
+        for service_type in services:
+            if service_type in self._services:
+                _logger.debug("Overriding %s with %s", service_type,
+                              services[service_type])
+            self._services[service_type] = services[service_type]
+        self.service_names = sorted(self._services.keys())
+
     def get_preference(self, service):
         """Get a service preference.