Add support for patroni replication user socket connection (#1865)

Close #1866

docs/SETTINGS.rst

@@ -293,6 +293,7 @@ PostgreSQL
     -  **bin\_dir**: Path to PostgreSQL binaries (pg_ctl, pg_rewind, pg_basebackup, postgres). The default value is an empty string meaning that PATH environment variable will be used to find the executables.
     -  **listen**: IP address + port that Postgres listens to; must be accessible from other nodes in the cluster, if you're using streaming replication. Multiple comma-separated addresses are permitted, as long as the port component is appended after to the last one with a colon, i.e. ``listen: 127.0.0.1,127.0.0.2:5432``. Patroni will use the first address from this list to establish local connections to the PostgreSQL node.
     -  **use\_unix\_socket**: specifies that Patroni should prefer to use unix sockets to connect to the cluster. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
+    -  **use\_unix\_socket\_repl**: specifies that Patroni should prefer to use unix sockets for replication user cluster connection. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
     -  **pgpass**: path to the `.pgpass <https://www.postgresql.org/docs/current/static/libpq-pgpass.html>`__ password file. Patroni creates this file before executing pg\_basebackup, the post_init script and under some other circumstances. The location must be writable by Patroni.
     -  **recovery\_conf**: additional configuration settings written to recovery.conf when configuring follower.
     -  **custom\_conf** : path to an optional custom ``postgresql.conf`` file, that will be used in place of ``postgresql.base.conf``. The file must exist on all cluster nodes, be readable by PostgreSQL and will be included from its location on the real ``postgresql.conf``. Note that Patroni will not monitor this file for changes, nor backup it. However, its settings can still be overridden by Patroni's own configuration facilities - see :ref:`dynamic configuration <dynamic_configuration>` for details.

features/environment.py

@@ -180,6 +180,7 @@ class PatroniController(AbstractController):
         config['postgresql']['data_dir'] = self._data_dir
         config['postgresql']['basebackup'] = [{'checkpoint': 'fast'}]
         config['postgresql']['use_unix_socket'] = os.name != 'nt'  # windows doesn't yet support unix-domain sockets
+        config['postgresql']['use_unix_socket_repl'] = os.name != 'nt'  # windows doesn't yet support unix-domain sockets
         config['postgresql']['pgpass'] = os.path.join(tempfile.gettempdir(), 'pgpass_' + name)
         config['postgresql']['parameters'].update({
             'logging_collector': 'on', 'log_destination': 'csvlog', 'log_directory': self._output_dir,

patroni/postgresql/config.py

@@ -877,25 +877,21 @@ class ConfigHandler(object):
     def resolve_connection_addresses(self):
         port = self._server_parameters['port']
         tcp_local_address = self._get_tcp_local_address()
-
-        local_address = {'port': port}
-        if self._config.get('use_unix_socket'):
-            unix_socket_directories = self._server_parameters.get('unix_socket_directories')
-            if unix_socket_directories is not None:
-                # fallback to tcp if unix_socket_directories is set, but there are no sutable values
-                local_address['host'] = self._get_unix_local_address(unix_socket_directories) or tcp_local_address
-
-            # if unix_socket_directories is not specified, but use_unix_socket is set to true - do our best
-            # to use default value, i.e. don't specify a host neither in connection url nor arguments
-        else:
-            local_address['host'] = tcp_local_address
-
-        self._local_address = local_address
-        self.local_replication_address = {'host': tcp_local_address, 'port': port}
-
         netloc = self._config.get('connect_address') or tcp_local_address + ':' + port
-        self._postgresql.connection_string = uri('postgres', netloc, self._postgresql.database)
 
+        unix_socket_directories = self._server_parameters.get('unix_socket_directories')
+        # fallback to tcp if unix_socket_directories is set, but there are no sutable values
+        unix_local_address = unix_socket_directories and\
+            self._get_unix_local_address(unix_socket_directories) or tcp_local_address
+
+        tcp_local_address = {'host': tcp_local_address, 'port': port}
+        unix_local_address = {'host': unix_local_address, 'port': port}
+
+        self._local_address = unix_local_address if self._config.get('use_unix_socket') else tcp_local_address
+        self.local_replication_address = unix_local_address\
+            if self._config.get('use_unix_socket_repl') else tcp_local_address
+
+        self._postgresql.connection_string = uri('postgres', netloc, self._postgresql.database)
         self._postgresql.set_connection_kwargs(self.local_connect_kwargs)
 
     def _get_pg_settings(self, names):

tests/test_postgresql.py

@@ -475,7 +475,8 @@ class TestPostgresql(BaseTestPostgresql):
         parameters = self._PARAMETERS.copy()
         parameters.pop('f.oo')
         parameters['wal_buffers'] = '512'
-        config = {'pg_hba': [''], 'pg_ident': [''], 'use_unix_socket': True, 'authentication': {},
+        config = {'pg_hba': [''], 'pg_ident': [''], 'use_unix_socket': True, 'use_unix_socket_repl': True,
+                  'authentication': {},
                   'retry_timeout': 10, 'listen': '*', 'krbsrvname': 'postgres', 'parameters': parameters}
         self.p.reload_config(config)
         mock_fetchone.side_effect = Exception