Change logging to JSON formatting for stdio

Author: Jens

pyproject.toml

@@ -25,6 +25,7 @@ dependencies = [
     "pydantic>=2.10.6",
     "anyio",
     "python-dotenv",
+    "python-json-logger>=2.0.7",
     "starlette",
     "uvicorn",
     "playwright>=1.50.0",

server/server.py

@@ -19,10 +19,12 @@
 from datetime import datetime
 from typing import Any, Dict, Optional, Tuple, Union
 import time
+import sys
 
 # Third-party imports
 import click
 from dotenv import load_dotenv
+from pythonjsonlogger import jsonlogger
 
 # Browser-use library imports
 from browser_use import Agent
@@ -38,8 +40,23 @@
 from langchain_core.language_models import BaseLanguageModel
 
 # Configure logging
-logging.basicConfig(level=logging.INFO)
-logger = logging.getLogger(__name__)
+logger = logging.getLogger()
+logger.handlers = []  # Remove any existing handlers
+handler = logging.StreamHandler(sys.stderr)
+formatter = jsonlogger.JsonFormatter('{"time":"%(asctime)s","level":"%(levelname)s","name":"%(name)s","message":"%(message)s"}')
+handler.setFormatter(formatter)
+logger.addHandler(handler)
+logger.setLevel(logging.INFO)
+
+# Ensure uvicorn also logs to stderr in JSON format
+uvicorn_logger = logging.getLogger("uvicorn")
+uvicorn_logger.handlers = []
+uvicorn_logger.addHandler(handler)
+
+# Ensure all other loggers use the same format
+logging.getLogger("browser_use").addHandler(handler)
+logging.getLogger("playwright").addHandler(handler)
+logging.getLogger("mcp").addHandler(handler)
 
 # Load environment variables
 load_dotenv()
@@ -845,7 +862,38 @@ async def startup_event():
 
     # Function to run uvicorn in a separate thread
     def run_uvicorn():
-        uvicorn.run(starlette_app, host="0.0.0.0", port=port)
+        # Configure uvicorn to use JSON logging
+        log_config = {
+            "version": 1,
+            "disable_existing_loggers": False,
+            "formatters": {
+                "json": {
+                    "()": "pythonjsonlogger.jsonlogger.JsonFormatter",
+                    "fmt": '{"time":"%(asctime)s","level":"%(levelname)s","name":"%(name)s","message":"%(message)s"}'
+                }
+            },
+            "handlers": {
+                "default": {
+                    "formatter": "json",
+                    "class": "logging.StreamHandler",
+                    "stream": "ext://sys.stderr",
+                }
+            },
+            "loggers": {
+                "": {"handlers": ["default"], "level": "INFO"},
+                "uvicorn": {"handlers": ["default"], "level": "INFO"},
+                "uvicorn.error": {"handlers": ["default"], "level": "INFO"},
+                "uvicorn.access": {"handlers": ["default"], "level": "INFO"},
+            }
+        }
+        
+        uvicorn.run(
+            starlette_app,
+            host="0.0.0.0",
+            port=port,
+            log_config=log_config,
+            log_level="info"
+        )
 
     # If proxy mode is enabled, run both the SSE server and mcp-proxy
     if stdio:

src/browser_use_mcp_server/cli.py

@@ -7,9 +7,28 @@
 
 import os
 import sys
+import json
+import logging
 import click
 import importlib.util
-
+from pythonjsonlogger import jsonlogger
+
+# Configure logging for CLI
+logger = logging.getLogger()
+logger.handlers = []  # Remove any existing handlers
+handler = logging.StreamHandler(sys.stderr)
+formatter = jsonlogger.JsonFormatter('{"time":"%(asctime)s","level":"%(levelname)s","name":"%(name)s","message":"%(message)s"}')
+handler.setFormatter(formatter)
+logger.addHandler(handler)
+logger.setLevel(logging.INFO)
+
+def log_error(message: str, error: Exception = None):
+    """Log error in JSON format to stderr"""
+    error_data = {
+        "error": message,
+        "traceback": str(error) if error else None
+    }
+    print(json.dumps(error_data), file=sys.stderr)
 
 def import_server_module():
     """
@@ -23,7 +42,6 @@ def import_server_module():
     try:
         # Try to import the server module
         import server.server
-
         return server.server
     except ImportError:
         # If running as an installed package, the server module might be elsewhere
@@ -37,6 +55,7 @@ def import_server_module():
                 spec.loader.exec_module(server_module)
                 return server_module
         except Exception as e:
+            log_error("Could not import server module", e)
             raise ImportError(f"Could not import server module: {e}")
 
         raise ImportError(
@@ -87,9 +106,7 @@ def run(
     SUBCOMMAND: should be 'server'
     """
     if subcommand != "server":
-        click.echo(
-            f"Unknown subcommand: {subcommand}. Only 'server' is supported.", err=True
-        )
+        log_error(f"Unknown subcommand: {subcommand}. Only 'server' is supported.")
         sys.exit(1)
 
     try:
@@ -131,11 +148,7 @@ def run(
             sys.argv = old_argv
 
     except Exception as e:
-        import traceback
-
-        click.echo(f"Error starting server: {e}", err=True)
-        click.echo("Detailed error:", err=True)
-        click.echo(traceback.format_exc(), err=True)
+        log_error("Error starting server", e)
         sys.exit(1)