cherrypick #47600 for serve logger fix (#47613)

otherwise `ray start` might exit immediately with no error output.

python/ray/serve/_private/logging_utils.py

@@ -279,6 +279,7 @@ def configure_component_logger(
     component_type: Optional[ServeComponentType] = None,
     max_bytes: Optional[int] = None,
     backup_count: Optional[int] = None,
+    stream_handler_only: bool = False,
 ):
     """Configure a logger to be used by a Serve component.
 
@@ -292,14 +293,22 @@ def configure_component_logger(
     logger.setLevel(logging_config.log_level)
     logger.handlers.clear()
 
-    # Only add stream handler if RAY_SERVE_LOG_TO_STDERR is True.
-    if RAY_SERVE_LOG_TO_STDERR:
+    # Only add stream handler if RAY_SERVE_LOG_TO_STDERR is True or if
+    # `stream_handler_only` is set to True.
+    if RAY_SERVE_LOG_TO_STDERR or stream_handler_only:
         stream_handler = logging.StreamHandler()
         stream_handler.setFormatter(ServeFormatter(component_name, component_id))
         stream_handler.addFilter(log_to_stderr_filter)
         stream_handler.addFilter(ServeContextFilter())
         logger.addHandler(stream_handler)
 
+    # Skip setting up file handler and stdout/stderr redirect if `stream_handler_only`
+    # is set to True. Logger such as default serve logger can be configured outside the
+    # context of a Serve component, we don't want those logs to redirect into serve's
+    # logger and log files.
+    if stream_handler_only:
+        return
+
     if logging_config.logs_dir:
         logs_dir = logging_config.logs_dir
     else:
@@ -344,8 +353,8 @@ def configure_component_logger(
     # Remove unwanted attributes from the log record.
     file_handler.addFilter(ServeLogAttributeRemovalFilter())
 
-    # Redirect print, stdout, and stderr to Serve logger.
-    if not RAY_SERVE_LOG_TO_STDERR:
+    # Redirect print, stdout, and stderr to Serve logger, only when it's on the replica.
+    if not RAY_SERVE_LOG_TO_STDERR and component_type == ServeComponentType.REPLICA:
         builtins.print = redirected_print
         sys.stdout = StreamToLogger(logger, logging.INFO, sys.stdout)
         sys.stderr = StreamToLogger(logger, logging.INFO, sys.stderr)
@@ -362,6 +371,7 @@ def configure_default_serve_logger():
         logging_config=LoggingConfig(),
         max_bytes=LOGGING_ROTATE_BYTES,
         backup_count=LOGGING_ROTATE_BACKUP_COUNT,
+        stream_handler_only=True,
     )
 
 

python/ray/serve/tests/test_logging.py

@@ -27,7 +27,9 @@
     ServeFormatter,
     StreamToLogger,
     configure_component_logger,
+    configure_default_serve_logger,
     get_serve_logs_dir,
+    redirected_print,
 )
 from ray.serve._private.utils import get_component_file_name
 from ray.serve.context import _get_global_client
@@ -871,5 +873,31 @@ def __call__(self):
             assert "cannot pickle" not in f.read()
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="Fail to create temp dir.")
+@pytest.mark.parametrize(
+    "ray_instance",
+    [
+        {"RAY_SERVE_LOG_TO_STDERR": "0"},
+    ],
+    indirect=True,
+)
+def test_configure_default_serve_logger_with_stderr_redirect(
+    serve_and_ray_shutdown, ray_instance, tmp_dir
+):
+    """Test configuring default serve logger with stderr redirect.
+
+    Default serve logger should only be configured with one StreamToLogger handler, and
+    print, stdout, and stderr should NOT be overridden and redirected to the logger.
+    """
+
+    configure_default_serve_logger()
+    serve_logger = logging.getLogger("ray.serve")
+    assert len(serve_logger.handlers) == 1
+    assert isinstance(serve_logger.handlers[0], logging.StreamHandler)
+    assert print != redirected_print
+    assert not isinstance(sys.stdout, StreamToLogger)
+    assert not isinstance(sys.stderr, StreamToLogger)
+
+
 if __name__ == "__main__":
     sys.exit(pytest.main(["-v", "-s", __file__]))