Merge pull request #504 from jlowin/uvicorn-config

src/fastmcp/server/server.py

@@ -760,24 +760,24 @@ class FastMCP(Generic[LifespanResultT]):
             path: Path for the endpoint (defaults to settings.streamable_http_path or settings.sse_path)
             uvicorn_config: Additional configuration for the Uvicorn server
         """
-        uvicorn_config = uvicorn_config or {}
-        uvicorn_config.setdefault("timeout_graceful_shutdown", 0)
-        # lifespan is required for streamable http
-        uvicorn_config["lifespan"] = "on"
-
         host = host or self.settings.host
         port = port or self.settings.port
-        log_level = log_level or self.settings.log_level.lower()
+        default_log_level_to_use = log_level or self.settings.log_level.lower()
 
         app = self.http_app(path=path, transport=transport, middleware=middleware)
 
-        config = uvicorn.Config(
-            app,
-            host=host,
-            port=port,
-            log_level=log_level,
-            **uvicorn_config,
-        )
+        _uvicorn_config_from_user = uvicorn_config or {}
+
+        config_kwargs: dict[str, Any] = {
+            "timeout_graceful_shutdown": 0,
+            "lifespan": "on",
+        }
+        config_kwargs.update(_uvicorn_config_from_user)
+
+        if "log_config" not in config_kwargs and "log_level" not in config_kwargs:
+            config_kwargs["log_level"] = default_log_level_to_use
+
+        config = uvicorn.Config(app, host=host, port=port, **config_kwargs)
         server = uvicorn.Server(config)
         path = app.state.path.lstrip("/")  # type: ignore
         logger.info(
@@ -1040,9 +1040,6 @@ class FastMCP(Generic[LifespanResultT]):
         - The prompts are imported with prefixed names using the
           prompt_separator Example: If server has a prompt named
           "weather_prompt", it will be available as "weather_weather_prompt"
-        - The mounted server's lifespan will be executed when the parent
-          server's lifespan runs, ensuring that any setup needed by the mounted
-          server is performed
 
         Args:
             prefix: The prefix to use for the mounted server server: The FastMCP

tests/server/test_logging.py

@@ -0,0 +1,176 @@
+import asyncio
+import logging
+from unittest.mock import AsyncMock, Mock, patch
+
+import pytest
+
+from fastmcp.server.server import FastMCP
+
+
+class CustomLogFormatterForTest(logging.Formatter):
+    def format(self, record: logging.LogRecord) -> str:
+        return f"TEST_FORMAT::{record.levelname}::{record.name}::{record.getMessage()}"
+
+
+@pytest.fixture
+def mcp_server() -> FastMCP:
+    return FastMCP(name="TestLogServer")
+
+
+@patch("fastmcp.server.server.uvicorn.Server")
+@patch("fastmcp.server.server.uvicorn.Config")
+async def test_uvicorn_logging_default_level(
+    mock_uvicorn_config_constructor: Mock,
+    mock_uvicorn_server_constructor: Mock,
+    mcp_server: FastMCP,
+):
+    """Tests that FastMCP passes log_level to uvicorn.Config if no log_config is given."""
+    mock_server_instance = AsyncMock()
+    mock_uvicorn_server_constructor.return_value = mock_server_instance
+    serve_finished_event = asyncio.Event()
+    mock_server_instance.serve.side_effect = serve_finished_event.wait
+
+    test_log_level = "warning"
+
+    server_task = asyncio.create_task(
+        mcp_server.run_http_async(log_level=test_log_level, port=8003)
+    )
+    await asyncio.sleep(0.01)
+
+    mock_uvicorn_config_constructor.assert_called_once()
+    _, kwargs_config = mock_uvicorn_config_constructor.call_args
+
+    assert kwargs_config.get("log_level") == test_log_level.lower()
+    assert "log_config" not in kwargs_config
+
+    mock_uvicorn_server_constructor.assert_called_once_with(
+        mock_uvicorn_config_constructor.return_value
+    )
+    mock_server_instance.serve.assert_awaited_once()
+
+    server_task.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await server_task
+
+
+@patch("fastmcp.server.server.uvicorn.Server")
+@patch("fastmcp.server.server.uvicorn.Config")
+async def test_uvicorn_logging_with_custom_log_config(
+    mock_uvicorn_config_constructor: Mock,
+    mock_uvicorn_server_constructor: Mock,
+    mcp_server: FastMCP,
+):
+    """Tests that FastMCP passes log_config to uvicorn.Config and not log_level."""
+    mock_server_instance = AsyncMock()
+    mock_uvicorn_server_constructor.return_value = mock_server_instance
+    serve_finished_event = asyncio.Event()
+    mock_server_instance.serve.side_effect = serve_finished_event.wait
+
+    sample_log_config = {
+        "version": 1,
+        "disable_existing_loggers": False,
+        "formatters": {
+            "test_formatter": {
+                "()": "tests.server.test_logging.CustomLogFormatterForTest"
+            }
+        },
+        "handlers": {
+            "test_handler": {
+                "formatter": "test_formatter",
+                "class": "logging.StreamHandler",
+                "stream": "ext://sys.stdout",
+            }
+        },
+        "loggers": {
+            "uvicorn.error": {
+                "handlers": ["test_handler"],
+                "level": "INFO",
+                "propagate": False,
+            }
+        },
+    }
+
+    server_task = asyncio.create_task(
+        mcp_server.run_http_async(
+            uvicorn_config={"log_config": sample_log_config}, port=8004
+        )
+    )
+    await asyncio.sleep(0.01)
+
+    mock_uvicorn_config_constructor.assert_called_once()
+    _, kwargs_config = mock_uvicorn_config_constructor.call_args
+
+    assert kwargs_config.get("log_config") == sample_log_config
+    assert "log_level" not in kwargs_config
+
+    mock_uvicorn_server_constructor.assert_called_once_with(
+        mock_uvicorn_config_constructor.return_value
+    )
+    mock_server_instance.serve.assert_awaited_once()
+
+    server_task.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await server_task
+
+
+@patch("fastmcp.server.server.uvicorn.Server")
+@patch("fastmcp.server.server.uvicorn.Config")
+async def test_uvicorn_logging_custom_log_config_overrides_log_level_param(
+    mock_uvicorn_config_constructor: Mock,
+    mock_uvicorn_server_constructor: Mock,
+    mcp_server: FastMCP,
+):
+    """Tests log_config precedence if log_level is also passed to run_http_async."""
+    mock_server_instance = AsyncMock()
+    mock_uvicorn_server_constructor.return_value = mock_server_instance
+    serve_finished_event = asyncio.Event()
+    mock_server_instance.serve.side_effect = serve_finished_event.wait
+
+    sample_log_config = {
+        "version": 1,
+        "disable_existing_loggers": False,
+        "formatters": {
+            "test_formatter": {
+                "()": "tests.server.test_logging.CustomLogFormatterForTest"
+            }
+        },
+        "handlers": {
+            "test_handler": {
+                "formatter": "test_formatter",
+                "class": "logging.StreamHandler",
+                "stream": "ext://sys.stdout",
+            }
+        },
+        "loggers": {
+            "uvicorn.error": {
+                "handlers": ["test_handler"],
+                "level": "INFO",
+                "propagate": False,
+            }
+        },
+    }
+    explicit_log_level = "debug"
+
+    server_task = asyncio.create_task(
+        mcp_server.run_http_async(
+            log_level=explicit_log_level,
+            uvicorn_config={"log_config": sample_log_config},
+            port=8005,
+        )
+    )
+    await asyncio.sleep(0.01)
+
+    mock_uvicorn_config_constructor.assert_called_once()
+    _, kwargs_config = mock_uvicorn_config_constructor.call_args
+
+    assert kwargs_config.get("log_config") == sample_log_config
+    assert "log_level" not in kwargs_config
+
+    mock_uvicorn_server_constructor.assert_called_once_with(
+        mock_uvicorn_config_constructor.return_value
+    )
+    mock_server_instance.serve.assert_awaited_once()
+
+    server_task.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await server_task

tests/server/test_proxy.py

@@ -74,7 +74,7 @@ async def test_create_proxy(fastmcp_server):
     # Create a client
     client = Client(transport=FastMCPTransport(fastmcp_server))
 
-    server = FastMCPProxy.from_client(client)
+    server = FastMCPProxy.as_proxy(client)
 
     assert isinstance(server, FastMCPProxy)
     assert isinstance(server, FastMCP)