Unify Patroni and Patronictl configuration

A Patroni configuration should be enough for Patronictl
The previous dcs_api url style is still supported.

patroni/ctl.py

@@ -33,6 +33,7 @@ class PatroniCtlException(ClickException):
 def parse_dcs(dcs):
     """
     Break up the provided dcs string
+    >>> parse_dcs(None)
     >>> parse_dcs('localhost') == {'etcd': {'host': 'localhost:4001'}}
     True
     >>> parse_dcs('localhost:8500') == {'consul': {'host': 'localhost:8500'}}
@@ -44,7 +45,7 @@ def parse_dcs(dcs):
     """
 
     if not dcs:
-        return {}
+        return None
 
     parsed = urlparse(dcs)
     scheme = parsed.scheme
@@ -80,8 +81,10 @@ def load_config(path, dcs):
 
     if dcs:
         config['dcs'] = parse_dcs(dcs)
+    elif 'dcs_api' in config:
+        config['dcs'] = parse_dcs(config['dcs_api'])
     else:
-        config['dcs'] = parse_dcs(config.get('dcs_api'))
+        config = {'dcs': config}
 
     return config
 

tests/test_ctl.py

@@ -40,6 +40,8 @@ def test_rw_config():
     load_config(CONFIG_FILE_PATH, None)
     load_config(CONFIG_FILE_PATH, '0.0.0.0')
 
+    store_config({'dcs_api': None}, CONFIG_FILE_PATH)
+    load_config(CONFIG_FILE_PATH, None)
 
 @patch('patroni.ctl.load_config', Mock(return_value={'dcs': {'etcd': {'host': 'localhost:4001'}}}))
 class TestCtl(unittest.TestCase):