[DPE-4032] Exposed passwords on postgresql SQL queries logging (#495)

* add integration test

* bump postgresql.py lib to 28

lib/charms/postgresql_k8s/v0/postgresql.py

@@ -36,7 +36,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 26
+LIBPATCH = 28
 
 INVALID_EXTRA_USER_ROLE_BLOCKING_MESSAGE = "invalid role(s) for extra user roles"
 
@@ -111,20 +111,19 @@ def __init__(
         self.system_users = system_users
 
     def _connect_to_database(
-        self, database: str = None, connect_to_current_host: bool = False
+        self, database: str = None, database_host: str = None
     ) -> psycopg2.extensions.connection:
         """Creates a connection to the database.
 
         Args:
             database: database to connect to (defaults to the database
                 provided when the object for this class was created).
-            connect_to_current_host: whether to connect to the current host
-                instead of the primary host.
+            database_host: host to connect to instead of the primary host.
 
         Returns:
              psycopg2 connection object.
         """
-        host = self.current_host if connect_to_current_host else self.primary_host
+        host = database_host if database_host is not None else self.primary_host
         connection = psycopg2.connect(
             f"dbname='{database if database else self.database}' user='{self.user}' host='{host}'"
             f"password='{self.password}' connect_timeout=1"
@@ -231,7 +230,10 @@ def create_user(
                 user_definition += f"WITH {'NOLOGIN' if user == 'admin' else 'LOGIN'}{' SUPERUSER' if admin else ''} ENCRYPTED PASSWORD '{password}'{'IN ROLE admin CREATEDB' if admin_role else ''}"
                 if privileges:
                     user_definition += f' {" ".join(privileges)}'
+                cursor.execute(sql.SQL("BEGIN;"))
+                cursor.execute(sql.SQL("SET LOCAL log_statement = 'none';"))
                 cursor.execute(sql.SQL(f"{user_definition};").format(sql.Identifier(user)))
+                cursor.execute(sql.SQL("COMMIT;"))
 
                 # Add extra user roles to the new user.
                 if roles:
@@ -388,7 +390,7 @@ def get_postgresql_text_search_configs(self) -> Set[str]:
             Set of PostgreSQL text search configs.
         """
         with self._connect_to_database(
-            connect_to_current_host=True
+            database_host=self.current_host
         ) as connection, connection.cursor() as cursor:
             cursor.execute("SELECT CONCAT('pg_catalog.', cfgname) FROM pg_ts_config;")
             text_search_configs = cursor.fetchall()
@@ -401,7 +403,7 @@ def get_postgresql_timezones(self) -> Set[str]:
             Set of PostgreSQL timezones.
         """
         with self._connect_to_database(
-            connect_to_current_host=True
+            database_host=self.current_host
         ) as connection, connection.cursor() as cursor:
             cursor.execute("SELECT name FROM pg_timezone_names;")
             timezones = cursor.fetchall()
@@ -434,7 +436,7 @@ def is_tls_enabled(self, check_current_host: bool = False) -> bool:
         """
         try:
             with self._connect_to_database(
-                connect_to_current_host=check_current_host
+                database_host=self.current_host if check_current_host else None
             ) as connection, connection.cursor() as cursor:
                 cursor.execute("SHOW ssl;")
                 return "on" in cursor.fetchone()[0]
@@ -502,24 +504,32 @@ def set_up_database(self) -> None:
             if connection is not None:
                 connection.close()
 
-    def update_user_password(self, username: str, password: str) -> None:
+    def update_user_password(
+        self, username: str, password: str, database_host: str = None
+    ) -> None:
         """Update a user password.
 
         Args:
             username: the user to update the password.
             password: the new password for the user.
+            database_host: the host to connect to.
 
         Raises:
             PostgreSQLUpdateUserPasswordError if the password couldn't be changed.
         """
         connection = None
         try:
-            with self._connect_to_database() as connection, connection.cursor() as cursor:
+            with self._connect_to_database(
+                database_host=database_host
+            ) as connection, connection.cursor() as cursor:
+                cursor.execute(sql.SQL("BEGIN;"))
+                cursor.execute(sql.SQL("SET LOCAL log_statement = 'none';"))
                 cursor.execute(
                     sql.SQL("ALTER USER {} WITH ENCRYPTED PASSWORD '" + password + "';").format(
                         sql.Identifier(username)
                     )
                 )
+                cursor.execute(sql.SQL("COMMIT;"))
         except psycopg2.Error as e:
             logger.error(f"Failed to update user password: {e}")
             raise PostgreSQLUpdateUserPasswordError()
@@ -610,7 +620,7 @@ def validate_date_style(self, date_style: str) -> bool:
         """
         try:
             with self._connect_to_database(
-                connect_to_current_host=True
+                database_host=self.current_host
             ) as connection, connection.cursor() as cursor:
                 cursor.execute(
                     sql.SQL(

tests/integration/test_password_rotation.py

@@ -19,6 +19,7 @@
     get_primary,
     get_unit_address,
     restart_patroni,
+    run_command_on_unit,
     set_password,
 )
 
@@ -178,3 +179,18 @@ async def test_no_password_change_on_invalid_password(ops_test: OpsTest) -> None
     password2 = await get_password(ops_test, unit_name=leader, username="replication")
     # The password didn't change
     assert password1 == password2
+
+
+@pytest.mark.group(1)
+async def test_no_password_exposed_on_logs(ops_test: OpsTest) -> None:
+    """Test that passwords don't get exposed on postgresql logs."""
+    for unit in ops_test.model.applications[APP_NAME].units:
+        try:
+            logs = await run_command_on_unit(
+                ops_test,
+                unit.name,
+                "grep PASSWORD /var/snap/charmed-postgresql/common/var/log/postgresql/postgresql-*.log",
+            )
+        except Exception:
+            continue
+        assert len(logs) == 0, f"Sensitive information detected on {unit.name} logs"