Extensions handler for Nailgun

Added new API handler /extensions/ which returns a list of available
extensions.

Co-Authored-By: Sylwester Brzeczkowski <sbrzeczkowski@mirantis.com>

Change-Id: I072f3e4d9cd8f71498a20312af7c2016e951456d
Implements: blueprint extensions-management
Partial-Bug: #1614526

nailgun/nailgun/api/v1/handlers/extension.py

@@ -0,0 +1,30 @@
+#    Copyright 2016 Mirantis, Inc.
+#
+#    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.
+
+from nailgun.api.v1.handlers.base import BaseHandler
+from nailgun.api.v1.handlers.base import serialize
+
+from nailgun.extensions import get_all_extensions
+
+
+class ExtensionHandler(BaseHandler):
+    """Exception Handler"""
+
+    @serialize
+    def GET(self):
+        """:returns: JSONized list of available extensions.
+
+        :http: * 200 (OK)
+        """
+        return [ext.to_dict() for ext in get_all_extensions()]

nailgun/nailgun/api/v1/urls.py

@@ -55,6 +55,8 @@ from nailgun.api.v1.handlers.cluster_plugin_link \
 from nailgun.api.v1.handlers.deployment_history \
     import DeploymentHistoryCollectionHandler
 
+from nailgun.api.v1.handlers.extension import ExtensionHandler
+
 from nailgun.api.v1.handlers.logs import LogEntryCollectionHandler
 from nailgun.api.v1.handlers.logs import LogPackageDefaultConfig
 from nailgun.api.v1.handlers.logs import LogPackageHandler
@@ -252,6 +254,8 @@ urls = (
     r'/clusters/(?P<cluster_id>\d+)/plugin_links/(?P<obj_id>\d+)/?$',
     ClusterPluginLinkHandler,
 
+    r'/extensions/?$',
+    ExtensionHandler,
     r'/clusters/(?P<cluster_id>\d+)/extensions/?$',
     ClusterExtensionsHandler,
 

nailgun/nailgun/extensions/base.py

@@ -248,3 +248,11 @@ class BaseExtension(object):
     def on_before_provisioning_serialization(cls, cluster, nodes,
                                              ignore_customized):
         """Callback which gets executed before provisioning serialization"""
+
+    def to_dict(self):
+        return {
+            "name": self.name,
+            "version": self.version,
+            "description": self.description,
+            "provides": self.provides,
+        }

nailgun/nailgun/test/integration/test_extension_handler.py

@@ -0,0 +1,69 @@
+#    Copyright 2016 Mirantis, Inc.
+#
+#    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 mock
+
+from nailgun import extensions
+from nailgun.test.base import BaseTestCase
+from nailgun.utils import reverse
+
+
+class TestExtensionHandler(BaseTestCase):
+
+    def test_get_extensions_list(self):
+        class FakeExtension(extensions.BaseExtension):
+            @property
+            def name(self):
+                return self._name
+
+            @property
+            def version(self):
+                return self._version
+
+            @property
+            def description(self):
+                return self._description
+
+            def __init__(self, name, version, description, provides):
+                self._name = name
+                self._version = version
+                self._description = description
+                self.provides = provides
+
+        exts = [FakeExtension('ex1', '1.0.1', 'descr #1', ['method_call_1']),
+                FakeExtension('ex2', '1.2.3', 'descr #2', ['method_call_2'])]
+
+        with mock.patch('nailgun.api.v1.handlers.extension.get_all_extensions',
+                        return_value=exts):
+
+            resp = self.app.get(
+                reverse('ExtensionHandler'),
+                headers=self.default_headers,
+            )
+
+        self.assertEqual(resp.status_code, 200)
+        expected_body = [
+            {'name': 'ex1',
+             'version': '1.0.1',
+             'description': 'descr #1',
+             'provides': ['method_call_1'],
+             },
+            {'name': 'ex2',
+             'version': '1.2.3',
+             'description': 'descr #2',
+             'provides': ['method_call_2'],
+             },
+        ]
+        self.assertEqual(len(resp.json_body), 2)
+        self.assertEqual(expected_body, resp.json_body)

nailgun/nailgun/test/unit/test_extensions.py

@@ -53,6 +53,13 @@ class BaseExtensionCase(BaseTestCase):
 
 class TestBaseExtension(BaseExtensionCase):
 
+    def test_extension_to_dict(self):
+        serialized = self.extension.to_dict()
+        self.assertEqual('ext_name', serialized['name'])
+        self.assertEqual('1.0.0', serialized['version'])
+        self.assertEqual('ext description', serialized['description'])
+        self.assertEqual([], serialized['provides'])
+
     def test_alembic_table_version(self):
         self.assertEqual(
             self.extension.alembic_table_version(),