Add VM Provider factory

To be able to easy extend VM Providers, and use multiple VMProviders
in the same time

So to extend VM provider by your own you have to do couple of simple things

Add new subclass of rally.vmprovider.VMProviderFactory to any modules in
rally.vmprovider.VMProvider.providers.some_module, and implement 4 next methods:

1) upload_image()
2) destroy_image()
3) create_vms()
4) destroy_vms()

rally/exceptions.py

@@ -92,5 +92,9 @@ class NoSuchEngine(NotFoundException):
     msg_fmt = _("There is no engine with name `%(engine_name)s`.")
 
 
+class NoSuchVMProvider(NotFoundException):
+    msg_fmt = _("There is no vm provider with name `%(vm_provider_name)s`.")
+
+
 class TaskNotFound(NotFoundException):
     msg_fmt = _("Task with uuid=%(uuid)s not found.")

rally/vmprovider/provider.py

@@ -0,0 +1,74 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2013: Mirantis Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import abc
+
+from rally import exceptions
+from rally import utils
+
+
+class VMProviderFactory(object):
+    """rally.vmprovider.provider.VMProviderFactory is base class for providers
+
+    All provider should be added to rally.vmprovider.providers.some_moduule.py
+    and implement 4 methods:
+        *) upload_image
+        *) destroy_image
+        *) create_vms
+        *) destroy_vms.
+    """
+    __metaclass__ = abc.ABCMeta
+
+    @staticmethod
+    def get_provider(name, config):
+        """Returns instance of vm provider by name."""
+        for provider in utils.itersubclasses(VMProviderFactory):
+            if name == provider.__name__:
+                return provider(config)
+        raise exceptions.NoSuchVMProvider(vm_provider_name=name)
+
+    @staticmethod
+    def get_available_providers():
+        """Returns list of names of available engines."""
+        return [e.__name__ for e in utils.itersubclasses(VMProviderFactory)]
+
+    @abc.abstractmethod
+    def upload_image(self, image):
+        """Upload image that could be used in creating new vms.
+        :image: Image file
+        Returns uuid of added image.
+        """
+        pass
+
+    @abc.abstractmethod
+    def destroy_image(self, image_uuid):
+        """Destroy image by image_uuid."""
+        pass
+
+    @abc.abstractmethod
+    def create_vms(self, image_uuid=None, amount=1):
+        """Create VMs with chosen image.
+        :param image_uuid: Indetificator of image
+        :param amount: amount of required VMs
+        Returns list of VMs uuids.
+        """
+        pass
+
+    @abc.abstractmethod
+    def destroy_vms(self, vm_uuids):
+        """Destroy already created vms by vm_uuids."""
+        pass

tests/vmprovider/test_vm_provider.py

@@ -0,0 +1,73 @@
+
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2013: Mirantis Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+"""Test for vm providers."""
+
+from rally import exceptions
+from rally import test
+from rally.vmprovider import provider as vm_provider
+
+
+class VMProviderTestCase(test.NoDBTestCase):
+
+    def test_get_provider_not_found(self):
+        self.assertRaises(exceptions.NoSuchVMProvider,
+                          vm_provider.VMProviderFactory.get_provider,
+                          "non_existing", None)
+
+    def _create_fake_providers(self):
+        class ProviderMixIn(object):
+            def upload_image(self, image):
+                pass
+
+            def destroy_image(self, image_uuid):
+                pass
+
+            def create_vms(self, image_uuid=None, amount=1):
+                pass
+
+            def destroy_vms(self, vm_uuids):
+                pass
+
+        class ProviderA(ProviderMixIn, vm_provider.VMProviderFactory):
+            def __init__(self, config):
+                pass
+
+        class ProviderB(ProviderMixIn, vm_provider.VMProviderFactory):
+            def __init__(self, config):
+                pass
+
+        class ProviderC(ProviderB):
+            def __init__(self, config):
+                pass
+
+        return [ProviderA, ProviderB, ProviderC]
+
+    def test_get_provider(self):
+        for p in self._create_fake_providers():
+                p_inst = vm_provider.VMProviderFactory.get_provider(p.__name__,
+                                                                    None)
+                # TODO(boris-42): make it work through assertIsInstance
+                self.assertEqual(str(type(p_inst)), str(p))
+
+    def test_get_all_provider(self):
+        provider = [p.__name__ for p in self._create_fake_providers()]
+        real_provider = vm_provider.VMProviderFactory.get_available_providers()
+        self.assertEqual(sorted(provider), sorted(real_provider))
+
+    def test_vm_prvoider_factory_is_abstract(self):
+            self.assertRaises(TypeError, vm_provider.VMProviderFactory)