Move cfg file creation to driver

Added code to load the file backend as a driver in engine __init__,
and a function in FileBackend to create cfg files.

Also added extra field in engine.cfg to specify what kind of backend
to use.

Change-Id: I6d3f24d4f676c72c94afff2c4c7f54a35cf1d4b1

entropy/__main__.py

@@ -102,8 +102,6 @@ def start_engine(args):
         }
     }
     utils.write_yaml(cfg, engine_cfg)
-    # create cfg files
-    utils.create_files([cfg_data['audit_cfg'], cfg_data['repair_cfg']])
     LOG.info('Added %s to engine cfg', args.name)
     entropy_engine = Engine(args.name, **cfg_data)
     entropy_engine.run()

entropy/backends/file_backend.py

@@ -11,13 +11,21 @@
 # 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 os
-
 from entropy.backends import base
+from entropy import utils
 
 
 class FileBackend(base.Backend):
     """A directory based backend."""
     def __init__(self, conf):
-        super(FileBackend, self).__init(conf)
-        self.path = os.path.abspath(conf['path'])
+        super(FileBackend, self).__init__(conf)
+        self.setup()
+
+    def setup(self):
+        utils.create_files([self._conf['audit_cfg'], self._conf['repair_cfg']])
+
+    def open(self):
+        pass
+
+    def close(self):
+        pass

entropy/engine.py

@@ -27,6 +27,7 @@ from kombu import Exchange
 from kombu import Queue
 import pause
 import six
+from stevedore import driver
 
 from entropy import exceptions
 from entropy import utils
@@ -40,6 +41,7 @@ class Engine(object):
         Engine.set_logger(**cfg_data)
         # constants
         # TODO(praneshp): Hardcode for now, could/should be cmdline input
+        self._engine_cfg_data = cfg_data
         self.max_workers = 8
         self.audit_type = 'audit'
         self.repair_type = 'repair'
@@ -52,6 +54,8 @@ class Engine(object):
         self.serializer_schedule = cfg_data['serializer_schedule']
         self.engine_timeout = cfg_data['engine_timeout']
         # TODO(praneshp): Assuming cfg files are in 1 dir. Change later
+        self._backend = cfg_data['backend']
+        self._backend_driver = self.get_backend()
         self.cfg_dir = os.path.dirname(self.audit_cfg)
         self.log_file = cfg_data['log_file']
         self.executor = cf.ThreadPoolExecutor(max_workers=self.max_workers)
@@ -73,6 +77,15 @@ class Engine(object):
         LOG.addHandler(log_to_file)
         LOG.propagate = False
 
+    def get_backend(self):
+        backend = driver.DriverManager(
+            namespace='entropy.backend',
+            name=self._backend,
+            invoke_on_load=True,
+            invoke_args=(self._engine_cfg_data,),
+        )
+        return backend.driver
+
     def run(self):
         LOG.info('Starting Scheduler for %s', self.name)
         self.start_scheduler()
@@ -189,7 +202,7 @@ class Engine(object):
         try:
             pause.until(execution_time)
             LOG.info("Time: %s, Starting %s", execution_time, audit_list)
-            audits = utils.load_yaml(self.audit_cfg)
+            audits = self._backend_driver.get_audits()
             audit_futures = []
             for audit in audit_list:
                 audit_name = audit['name']

entropy/examples/cfg/test.cfg

@@ -5,4 +5,4 @@ test:
     log_format: "%(filename)s %(lineno)s %(message)s"
     serializer_schedule: "*/2 * * * *"
     engine_timeout: "25"
-    backend: EntropyFileBackend
+    backend: file