Extend list of postgres parameters controlled by Patroni

These parameters usually must be the same across all cluster nodes and
therefore must be set only via global configuration and always passed as
a list of postgres arguments (via pg_ctl) to make it not possible
accidentally change them by 'ALTER SYSTEM'

patroni/config.py

@@ -37,7 +37,7 @@ class Config(object):
         'ttl': 30, 'loop_wait': 10, 'retry_timeout': 10,
         'maximum_lag_on_failover': 1048576,
         'postgresql': {
-            'parameters': Postgresql.CMDLINE_OPTIONS
+            'parameters': {p: v[0] for p, v in Postgresql.CMDLINE_OPTIONS.items()}
         }
     }
 
@@ -133,11 +133,7 @@ class Config(object):
     def _process_postgresql_parameters(self, parameters, is_local=False):
         ret = {}
         for name, value in (parameters or {}).items():
-            if (is_local and name not in self.__DEFAULT_CONFIG['postgresql']['parameters']) \
-                or not ((name == 'wal_level' and value not in ('hot_standby', 'logical')) or
-                        (name in ('max_replication_slots', 'max_wal_senders', 'wal_keep_segments') and
-                         int(value) < self.__DEFAULT_CONFIG['postgresql']['parameters'][name]) or
-                        name in ('hot_standby', 'wal_log_hints')):
+            if name not in Postgresql.CMDLINE_OPTIONS or not is_local and Postgresql.CMDLINE_OPTIONS[name][1](value):
                 ret[name] = value
         return ret
 

patroni/postgresql.py

@@ -8,7 +8,7 @@ import tempfile
 import time
 
 from patroni.exceptions import PostgresConnectionException, PostgresException
-from patroni.utils import compare_values, parse_int, Retry, RetryFailedError
+from patroni.utils import compare_values, parse_bool, parse_int, Retry, RetryFailedError
 from six import string_types
 from six.moves.urllib_parse import urlparse
 from threading import Lock
@@ -48,15 +48,28 @@ class Postgresql(object):
     # These parameters could be changed only globally, i.e. via DCS.
     # P.S. 'listen_addresses' and 'port' are added here just for convenience, to mark them
     # as a parameters which should always be passed through command line.
+    #
+    # Format:
+    #  key - parameter name
+    #  value - tuple(default_value, check_function, min_version)
+    #    default_value -- some sane default value
+    #    check_function -- if the new value is not correct must return `!False`
+    #    min_version -- major version of PostgreSQL when parameter was introduced
     CMDLINE_OPTIONS = {
-        'listen_addresses': None,
-        'port': None,
-        'wal_level': 'hot_standby',
-        'hot_standby': 'on',
-        'max_wal_senders': 5,
-        'wal_keep_segments': 8,
-        'max_replication_slots': 5,
-        'wal_log_hints': 'on'
+        'listen_addresses': (None, lambda _: False, 9.1),
+        'port': (None, lambda _: False, 9.1),
+        'cluster_name': (None, lambda _: False, 9.5),
+        'wal_level': ('hot_standby', lambda v: v.lower() in ('hot_standby', 'logical'), 9.1),
+        'hot_standby': ('on', lambda _: False, 9.1),
+        'max_connections': (100, lambda v: int(v) >= 100, 9.1),
+        'max_wal_senders': (5, lambda v: int(v) >= 5, 9.1),
+        'wal_keep_segments': (8, lambda v: int(v) >= 8, 9.1),
+        'max_prepared_transactions': (0, lambda v: int(v) >= 0, 9.1),
+        'max_locks_per_transaction': (64, lambda v: int(v) >= 64, 9.1),
+        'track_commit_timestamp': ('off', lambda v: parse_bool(v) is not None, 9.5),
+        'max_replication_slots': (5, lambda v: int(v) >= 5, 9.4),
+        'max_worker_processes': (8, lambda v: int(v) >= 8, 9.4),
+        'wal_log_hints': ('on', lambda _: False, 9.4)
     }
 
     def __init__(self, config):
@@ -127,11 +140,10 @@ class Postgresql(object):
                 logger.exception('Failed to read PG_VERSION from %s', self._data_dir)
         return 0.0
 
-    @staticmethod
-    def get_server_parameters(config):
+    def get_server_parameters(self, config):
         parameters = config['parameters'].copy()
         listen_addresses, port = (config['listen'] + ':5432').split(':')[:2]
-        parameters.update({'listen_addresses': listen_addresses, 'port': port})
+        parameters.update({'cluster_name': self.scope, 'listen_addresses': listen_addresses, 'port': port})
         return parameters
 
     def resolve_connection_addresses(self):
@@ -496,8 +508,8 @@ class Postgresql(object):
         self._write_postgresql_conf()
         self.resolve_connection_addresses()
 
-        options = ' '.join("--{0}='{1}'".format(p, self._server_parameters[p]) for p in self.CMDLINE_OPTIONS
-                           if not (self._major_version < 9.4 and p in ('max_replication_slots', 'wal_log_hints')))
+        options = ' '.join("--{0}='{1}'".format(p, self._server_parameters[p]) for p, v in self.CMDLINE_OPTIONS.items()
+                           if self._major_version >= v[2])
 
         ret = subprocess.call(self._pg_ctl + ['start', '-o', options], env=env, preexec_fn=os.setsid) == 0
         self._pending_restart = False

tests/test_postgresql.py

@@ -153,8 +153,10 @@ def fake_listdir(path):
 @patch('subprocess.call', Mock(return_value=0))
 @patch('psycopg2.connect', psycopg2_connect)
 class TestPostgresql(unittest.TestCase):
-    _PARAMETERS = {'wal_level': 'hot_standby', 'max_replication_slots': 5, 'f.oo': 'bar', 'search_path': 'public',
-                   'hot_standby': 'on', 'max_wal_senders': 5, 'wal_keep_segments': 8, 'wal_log_hints': 'on'}
+    _PARAMETERS = {'wal_level': 'hot_standby', 'max_replication_slots': 5, 'f.oo': 'bar',
+                   'search_path': 'public', 'hot_standby': 'on', 'max_wal_senders': 5,
+                   'wal_keep_segments': 8, 'wal_log_hints': 'on', 'max_locks_per_transaction': 64,
+                   'max_worker_processes': 8, 'max_connections': 100, 'max_prepared_transactions': 0}
 
     @patch('subprocess.call', Mock(return_value=0))
     @patch('psycopg2.connect', psycopg2_connect)