Make config-download directory a git repository

Initialize the config-download directory as a git repository.
Snapshot and commit any changes to the config-download directory on
subsequent runs.

Change-Id: Ia1ca309cc7476bc84e101a3cd109352de3e0c06c

releasenotes/notes/config-download-git-repo-9a18681afbfb9136.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+     Initialize a git repository in the config-download directory and
+     automatically snapshot changes made to the repository.

tripleo_common/tests/utils/test_config.py

@@ -97,11 +97,13 @@ class TestConfig(base.TestCase):
         mock_mkdir.assert_has_calls(expected_mkdir_calls, any_order=True)
         mock_open.assert_has_calls(expected_calls, any_order=True)
 
+    @patch.object(ooo_config.git, 'Repo')
     @mock.patch('os.mkdir')
     @mock.patch('six.moves.builtins.open')
     @patch.object(ooo_config.shutil, 'rmtree')
     def test_overcloud_config_wrong_config_type(self, mock_rmtree,
-                                                mock_open, mock_mkdir):
+                                                mock_open, mock_mkdir,
+                                                mock_repo):
         args = {'name': 'overcloud', 'config_dir': '/tmp/tht',
                 'config_type': ['bad_config']}
         heat = mock.MagicMock()
@@ -414,6 +416,7 @@ class TestConfig(base.TestCase):
         self.assertRaises(ValueError,
                           self.config.download_config, stack, self.tmp_dir)
 
+    @patch.object(ooo_config.git, 'Repo')
     @patch.object(ooo_config.shutil, 'copyfile')
     @patch.object(ooo_config.Config, '_mkdir')
     @patch.object(ooo_config.Config, '_open_file')
@@ -424,7 +427,8 @@ class TestConfig(base.TestCase):
                                                    mock_rmtree,
                                                    mock_open,
                                                    mock_mkdir,
-                                                   mock_copyfile):
+                                                   mock_copyfile,
+                                                   mock_repo):
         config_type_list = ['config_settings', 'global_config_settings',
                             'logging_sources', 'monitoring_subscriptions',
                             'service_config_settings',

tripleo_common/utils/config.py

@@ -12,6 +12,7 @@
 # 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 git
 import json
 import logging
 import os
@@ -133,6 +134,19 @@ class Config(object):
             yaml.safe_dump(playbook, conf_file, default_flow_style=False)
         return sorted_tasks
 
+    def initialize_git_repo(self, dirname):
+        repo = git.Repo.init(dirname)
+        return repo
+
+    def snapshot_config_dir(self, repo, commit_message):
+        if repo.is_dirty(untracked_files=True):
+            self.log.info('Snapshotting {}'.format(repo.working_dir))
+            repo.index.add('*')
+            commit = repo.index.commit(commit_message)
+            self.log.info('Created commit {}'.format(commit.hexsha))
+        else:
+            self.log.info('No changes to commit')
+
     def _mkdir(self, dirname):
         if not os.path.exists(dirname):
             try:
@@ -390,12 +404,18 @@ class Config(object):
         return config_dir
 
     def download_config(self, name, config_dir, config_type=None,
-                        preserve_config_dir=True):
+                        preserve_config_dir=True, commit_message=None):
+
+        if commit_message is None:
+            commit_message = 'Automatic commit of config-download'
+
         # One step does it all
         stack = self.fetch_config(name)
         self.create_config_dir(config_dir, preserve_config_dir)
         self._mkdir(config_dir)
+        git_repo = self.initialize_git_repo(config_dir)
         self.log.info("Generating configuration under the directory: "
                       "%s" % config_dir)
         self.write_config(stack, name, config_dir, config_type)
+        self.snapshot_config_dir(git_repo, commit_message)
         return config_dir