Inptroduce postgresql.proxy_address (#2437)

It will be written to member key in DCS as the `proxy_url` and could be used/useful for service discovery.

docs/ENVIRONMENT.rst

@@ -123,6 +123,7 @@ PostgreSQL
 ----------
 -  **PATRONI\_POSTGRESQL\_LISTEN**: IP address + port that Postgres listens to. 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.
 -  **PATRONI\_POSTGRESQL\_CONNECT\_ADDRESS**: IP address + port through which Postgres is accessible from other nodes and applications.
+-  **PATRONI\_POSTGRESQL\_PROXY\_ADDRESS**: IP address + port through which a connection pool (e.g. pgbouncer) running next to Postgres is accessible. The value is written to the member key in DCS as ``proxy_url`` and could be used/useful for service discovery.
 -  **PATRONI\_POSTGRESQL\_DATA\_DIR**: The location of the Postgres data directory, either existing or to be initialized by Patroni.
 -  **PATRONI\_POSTGRESQL\_CONFIG\_DIR**: The location of the Postgres configuration directory, defaults to the data directory. Must be writable by Patroni.
 -  **PATRONI\_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.

docs/SETTINGS.rst

@@ -292,6 +292,7 @@ PostgreSQL
             -  **on\_start**: run this script when the postgres starts.
             -  **on\_stop**: run this script when the postgres stops.
     -  **connect\_address**: IP address + port through which Postgres is accessible from other nodes and applications.
+    -  **proxy\_address**: IP address + port through which a connection pool (e.g. pgbouncer) running next to Postgres is accessible. The value is written to the member key in DCS as ``proxy_url`` and could be used/useful for service discovery.
     -  **create\_replica\_methods**: an ordered list of the create methods for turning a Patroni node into a new replica.
        "basebackup" is the default method; other methods are assumed to refer to scripts, each of which is configured as its
        own config item. See :ref:`custom replica creation methods documentation <custom_replica_creation>` for further explanation.

patroni/config.py

@@ -227,7 +227,8 @@ class Config(object):
                 for name, value in (value or {}).items():
                     if name == 'parameters':
                         config['postgresql'][name].update(self._process_postgresql_parameters(value))
-                    elif name not in ('connect_address', 'listen', 'data_dir', 'pgpass', 'authentication'):
+                    elif name not in ('connect_address', 'proxy_address', 'listen',
+                                      'config_dir', 'data_dir', 'pgpass', 'authentication'):
                         config['postgresql'][name] = deepcopy(value)
             elif name == 'standby_cluster':
                 for name, value in (value or {}).items():
@@ -271,7 +272,8 @@ class Config(object):
                                         'cafile', 'ciphers', 'verify_client', 'http_extra_headers',
                                         'https_extra_headers', 'allowlist', 'allowlist_include_members'])
         _set_section_values('ctl', ['insecure', 'cacert', 'certfile', 'keyfile', 'keyfile_password'])
-        _set_section_values('postgresql', ['listen', 'connect_address', 'config_dir', 'data_dir', 'pgpass', 'bin_dir'])
+        _set_section_values('postgresql', ['listen', 'connect_address', 'proxy_address',
+                                           'config_dir', 'data_dir', 'pgpass', 'bin_dir'])
         _set_section_values('log', ['level', 'traceback_level', 'format', 'dateformat', 'max_queue_size',
                                     'dir', 'file_size', 'file_num', 'loggers'])
         _set_section_values('raft', ['data_dir', 'self_addr', 'partner_addrs', 'password', 'bind_addr'])

patroni/ha.py

@@ -192,6 +192,10 @@ class Ha(object):
                 'version': self.patroni.version
             }
 
+            proxy_url = self.state_handler.proxy_url
+            if proxy_url:
+                data['proxy_url'] = proxy_url
+
             if self.is_leader() and not self._rewind.checkpoint_after_promote():
                 data['checkpoint_after_promote'] = False
             tags = self.get_effective_tags()

patroni/postgresql/config.py

@@ -1017,6 +1017,9 @@ class ConfigHandler(object):
         if not local_connection_address_changed:
             self.resolve_connection_addresses()
 
+        proxy_addr = config.get('proxy_address')
+        self._postgresql.proxy_url = uri('postgres', proxy_addr, self._postgresql.database) if proxy_addr else None
+
         if conf_changed:
             self.write_postgresql_conf()
 

patroni/validator.py

@@ -370,6 +370,7 @@ schema = Schema({
   "postgresql": {
     "listen": validate_host_port_listen_multiple_hosts,
     "connect_address": validate_connect_address,
+    "proxy_address": validate_connect_address,
     "authentication": {
       "replication": userattributes,
       "superuser": userattributes,

postgres0.yml

@@ -99,6 +99,8 @@ bootstrap:
 postgresql:
   listen: 127.0.0.1:5432
   connect_address: 127.0.0.1:5432
+
+#  proxy_address: 127.0.0.1:5433  # The address of connection pool (e.g., pgbouncer) running next to Patroni/Postgres. Only for service discovery.
   data_dir: data/postgresql0
 #  bin_dir:
 #  config_dir:

postgres1.yml

@@ -93,6 +93,7 @@ bootstrap:
 postgresql:
   listen: 127.0.0.1:5433
   connect_address: 127.0.0.1:5433
+#  proxy_address: 127.0.0.1:5434  # The address of connection pool (e.g., pgbouncer) running next to Patroni/Postgres. Only for service discovery.
   data_dir: data/postgresql1
 #  bin_dir:
 #  config_dir:

postgres2.yml

@@ -90,6 +90,7 @@ bootstrap:
 postgresql:
   listen: 127.0.0.1:5434
   connect_address: 127.0.0.1:5434
+#  proxy_address: 127.0.0.1:5435  # The address of connection pool (e.g., pgbouncer) running next to Patroni/Postgres. Only for service discovery.
   data_dir: data/postgresql2
 #  bin_dir:
 #  config_dir:

tests/__init__.py

@@ -188,7 +188,8 @@ class PostgresInit(unittest.TestCase):
         self.p = Postgresql({'name': 'postgresql0', 'scope': 'batman', 'data_dir': data_dir,
                              'config_dir': data_dir, 'retry_timeout': 10,
                              'krbsrvname': 'postgres', 'pgpass': os.path.join(data_dir, 'pgpass0'),
-                             'listen': '127.0.0.2, 127.0.0.3:5432', 'connect_address': '127.0.0.2:5432',
+                             'listen': '127.0.0.2, 127.0.0.3:5432',
+                             'connect_address': '127.0.0.2:5432', 'proxy_address': '127.0.0.2:5433',
                              'authentication': {'superuser': {'username': 'foo', 'password': 'test'},
                                                 'replication': {'username': '', 'password': 'rep-pass'},
                                                 'rewind': {'username': 'rewind', 'password': 'test'}},

tests/test_config.py

@@ -40,6 +40,7 @@ class TestConfig(unittest.TestCase):
             'PATRONI_RESTAPI_ALLOWLIST_INCLUDE_MEMBERS': 'on',
             'PATRONI_POSTGRESQL_LISTEN': '0.0.0.0:5432',
             'PATRONI_POSTGRESQL_CONNECT_ADDRESS': '127.0.0.1:5432',
+            'PATRONI_POSTGRESQL_PROXY_ADDRESS': '127.0.0.1:5433',
             'PATRONI_POSTGRESQL_DATA_DIR': 'data/postgres0',
             'PATRONI_POSTGRESQL_CONFIG_DIR': 'data/postgres0',
             'PATRONI_POSTGRESQL_PGPASS': '/tmp/pgpass0',

tests/test_validator.py

@@ -63,6 +63,7 @@ config = {
     "postgresql": {
         "listen": "127.0.0.2,::1:543",
         "connect_address": "127.0.0.2:543",
+        "proxy_address": "127.0.0.2:5433",
         "authentication": {
             "replication": {"username": "user"},
             "superuser": {"username": "user"},