Add a DatabasePoolpostgres_connection_info

mypy.ini

@@ -255,3 +255,7 @@ ignore_missing_imports = True
 
 [mypy-ijson.*]
 ignore_missing_imports = True
+
+
+[mypy-psycopg2.*]
+ignore_missing_imports = True

synapse/storage/database.py

@@ -19,6 +19,7 @@ from collections import defaultdict
 from sys import intern
 from time import monotonic as monotonic_time
 from typing import (
+    TYPE_CHECKING,
     Any,
     Callable,
     Collection,
@@ -52,6 +53,9 @@ from synapse.storage.background_updates import BackgroundUpdater
 from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
 from synapse.storage.types import Connection, Cursor
 
+if TYPE_CHECKING:
+    from psycopg2.extensions import ConnectionInfo
+
 # python 3 does not have a maximum int value
 MAX_TXN_ID = 2 ** 63 - 1
 
@@ -395,6 +399,7 @@ class DatabasePool:
         hs,
         database_config: DatabaseConnectionConfig,
         engine: BaseDatabaseEngine,
+        db_conn: LoggingDatabaseConnection,
     ):
         self.hs = hs
         self._clock = hs.get_clock()
@@ -427,6 +432,13 @@ class DatabasePool:
         if isinstance(self.engine, Sqlite3Engine):
             self._unsafe_to_upsert_tables.add("user_directory_search")
 
+        # We store the connection info for later use when using postgres
+        # (primarily to allow things like the state auto compressor to connect
+        # to the DB).
+        self.postgres_connection_info: Optional["ConnectionInfo"] = None
+        if isinstance(self.engine, PostgresEngine):
+            self.postgres_connection_info = db_conn.info
+
         if self.engine.can_native_upsert:
             # Check ASAP (and then later, every 1s) to see if we have finished
             # background updates of tables that aren't safe to update.

synapse/storage/databases/__init__.py

@@ -61,7 +61,7 @@ class Databases:
                     databases=database_config.databases,
                 )
 
-                database = DatabasePool(hs, database_config, engine)
+                database = DatabasePool(hs, database_config, engine, db_conn)
 
                 if "main" in database_config.databases:
                     logger.info(