improved logging with sensible defaults (#391)

src/litserve/__init__.py

@@ -18,6 +18,9 @@
 from litserve.loggers import Logger
 from litserve.server import LitServer, Request, Response
 from litserve.specs import OpenAIEmbeddingSpec, OpenAISpec
+from litserve.utils import configure_logging
+
+configure_logging()
 
 __all__ = [
     "LitAPI",

src/litserve/utils.py

@@ -15,6 +15,7 @@
 import dataclasses
 import logging
 import pickle
+import sys
 from contextlib import contextmanager
 from typing import TYPE_CHECKING, AsyncIterator
 
@@ -87,3 +88,46 @@ class WorkerSetupStatus:
     READY: str = "ready"
     ERROR: str = "error"
     FINISHED: str = "finished"
+
+
+def configure_logging(
+    level=logging.INFO, format="%(asctime)s - %(name)s - %(levelname)s - %(message)s", stream=sys.stdout
+):
+    """Configure logging for the entire library with sensible defaults.
+
+    Args:
+        level (int): Logging level (default: logging.INFO)
+        format (str): Log message format string
+        stream (file-like): Output stream for logs
+
+    """
+    # Create a library-wide handler
+    handler = logging.StreamHandler(stream)
+
+    # Set formatter with user-configurable format
+    formatter = logging.Formatter(format)
+    handler.setFormatter(formatter)
+
+    # Configure root library logger
+    library_logger = logging.getLogger("litserve")
+    library_logger.setLevel(level)
+    library_logger.addHandler(handler)
+
+    # Prevent propagation to root logger to avoid duplicate logs
+    library_logger.propagate = False
+
+
+def set_log_level(level):
+    """Allow users to set the global logging level for the library."""
+    logging.getLogger("litserve").setLevel(level)
+
+
+def add_log_handler(handler):
+    """Allow users to add custom log handlers.
+
+    Example usage:
+    file_handler = logging.FileHandler('library_logs.log')
+    add_log_handler(file_handler)
+
+    """
+    logging.getLogger("litserve").addHandler(handler)

tests/test_logging.py

@@ -0,0 +1,60 @@
+import io
+import logging
+
+import pytest
+
+from litserve.utils import add_log_handler, configure_logging, set_log_level
+
+
+@pytest.fixture
+def log_stream():
+    return io.StringIO()
+
+
+def test_configure_logging(log_stream):
+    # Configure logging with test stream
+    configure_logging(level=logging.DEBUG, stream=log_stream)
+
+    # Get logger and log a test message
+    logger = logging.getLogger("litserve")
+    test_message = "Test debug message"
+    logger.debug(test_message)
+
+    # Verify log output
+    log_contents = log_stream.getvalue()
+    assert test_message in log_contents
+    assert "DEBUG" in log_contents
+    assert logger.propagate is False
+
+
+def test_set_log_level():
+    # Set log level to WARNING
+    set_log_level(logging.WARNING)
+
+    # Verify logger level
+    logger = logging.getLogger("litserve")
+    assert logger.level == logging.WARNING
+
+
+def test_add_log_handler():
+    # Create and add a custom handler
+    stream = io.StringIO()
+    custom_handler = logging.StreamHandler(stream)
+    add_log_handler(custom_handler)
+
+    # Verify handler is added
+    logger = logging.getLogger("litserve")
+    assert custom_handler in logger.handlers
+
+    # Test the handler works
+    test_message = "Test handler message"
+    logger.info(test_message)
+    assert test_message in stream.getvalue()
+
+
+@pytest.fixture(autouse=True)
+def cleanup_logger():
+    yield
+    logger = logging.getLogger("litserve")
+    logger.handlers.clear()
+    logger.setLevel(logging.INFO)

tests/test_loops.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import inspect
+import io
 import json
 import threading
 import time
@@ -229,7 +230,9 @@ def test_run_single_loop():
     assert response == ("UUID-001", ({"output": 16.0}, LitAPIStatus.OK))
 
 
-def test_run_single_loop_timeout(caplog):
+def test_run_single_loop_timeout():
+    stream = io.StringIO()
+    ls.configure_logging(stream=stream)
     lit_api = ls.test_examples.SimpleLitAPI()
     lit_api.setup(None)
     lit_api.request_timeout = 0.0001
@@ -248,7 +251,7 @@ def test_run_single_loop_timeout(caplog):
 
     request_queue.put((None, None, None, None))
     loop_thread.join()
-    assert "Request UUID-001 was waiting in the queue for too long" in caplog.text
+    assert "Request UUID-001 was waiting in the queue for too long" in stream.getvalue()
     assert isinstance(response_queues[0].get()[1][0], HTTPException), "Timeout should return an HTTPException"
 
 
@@ -284,7 +287,9 @@ def test_run_batched_loop():
     assert response_2 == ("UUID-002", ({"output": 25.0}, LitAPIStatus.OK))
 
 
-def test_run_batched_loop_timeout(caplog):
+def test_run_batched_loop_timeout():
+    stream = io.StringIO()
+    ls.configure_logging(stream=stream)
     lit_api = ls.test_examples.SimpleBatchedAPI()
     lit_api.setup(None)
     lit_api._sanitize(2, None)
@@ -309,7 +314,7 @@ def test_run_batched_loop_timeout(caplog):
     # Allow some time for the loop to process
     time.sleep(1)
 
-    assert "Request UUID-001 was waiting in the queue for too long" in caplog.text
+    assert "Request UUID-001 was waiting in the queue for too long" in stream.getvalue()
     resp1 = response_queues[0].get(timeout=10)[1]
     resp2 = response_queues[0].get(timeout=10)[1]
     assert isinstance(resp1[0], HTTPException), "First request was timed out"
@@ -348,7 +353,9 @@ def test_run_streaming_loop():
         assert response == {"output": f"{i}: Hello"}
 
 
-def test_run_streaming_loop_timeout(caplog):
+def test_run_streaming_loop_timeout():
+    stream = io.StringIO()
+    ls.configure_logging(stream=stream)
     lit_api = ls.test_examples.SimpleStreamAPI()
     lit_api.setup(None)
     lit_api.request_timeout = 0.1
@@ -370,7 +377,7 @@ def test_run_streaming_loop_timeout(caplog):
     request_queue.put((None, None, None, None))
     loop_thread.join()
 
-    assert "Request UUID-001 was waiting in the queue for too long" in caplog.text
+    assert "Request UUID-001 was waiting in the queue for too long" in stream.getvalue()
     response = response_queues[0].get(timeout=10)[1]
     assert isinstance(response[0], HTTPException), "request was timed out"