""" Comprehensive Error Handling Middleware Provides detailed error responses and logging for production use """ from datetime import datetime import json import logging import traceback from typing import Any, Dict, Optional import uuid from fastapi import HTTPException, Request, Response from fastapi.responses import JSONResponse from starlette.middleware.base import BaseHTTPMiddleware # Configure error logging error_logger = logging.getLogger("atom.errors") performance_logger = logging.getLogger("atom.performance") class ErrorHandlingMiddleware(BaseHTTPMiddleware): """Comprehensive error handling middleware""" def __init__(self, app, debug: bool = False): super().__init__(app) self.debug = debug self.setup_logging() def setup_logging(self): """Setup error logging configuration""" # Create file handler for errors error_handler = logging.FileHandler("logs/errors.log") error_handler.setLevel(logging.ERROR) error_formatter = logging.Formatter( '%(asctime)s - %(name)s - %(levelname)s - %(message)s' ) error_handler.setFormatter(error_formatter) error_logger.addHandler(error_handler) # Create performance handler perf_handler = logging.FileHandler("logs/performance.log") perf_handler.setLevel(logging.INFO) perf_handler.setFormatter(error_formatter) performance_logger.addHandler(perf_handler) async def dispatch(self, request: Request, call_next): """Process request and handle any errors""" # Generate request ID for tracking request_id = str(uuid.uuid4()) start_time = datetime.now() # Add request ID to request state request.state.request_id = request_id try: # Process the request response = await call_next(request) # Log performance metrics duration = (datetime.now() - start_time).total_seconds() self.log_performance(request, response, duration, request_id) # Add request ID to response headers response.headers["X-Request-ID"] = request_id return response except HTTPException as e: # Handle HTTP exceptions (client errors) return await self.handle_http_exception(e, request, request_id, start_time) except Exception as e: # Handle unexpected errors (server errors) return await self.handle_server_error(e, request, request_id, start_time) async def handle_http_exception( self, exception: HTTPException, request: Request, request_id: str, start_time: datetime ) -> JSONResponse: """Handle HTTP exceptions (4xx errors)""" error_response = { "error": { "type": "http_error", "code": exception.status_code, "message": exception.detail, "request_id": request_id, "timestamp": datetime.now().isoformat(), "path": str(request.url.path), "method": request.method } } # Add debug information in development if self.debug: error_response["debug"] = { "headers": dict(request.headers), "query_params": dict(request.query_params) } # Log the error error_logger.warning( f"HTTP {exception.status_code} - {request.method} {request.url.path} - " f"{exception.detail} - Request ID: {request_id}" ) return JSONResponse( status_code=exception.status_code, content=error_response ) async def handle_server_error( self, exception: Exception, request: Request, request_id: str, start_time: datetime ) -> JSONResponse: """Handle server errors (5xx errors)""" # Get full traceback error_traceback = traceback.format_exc() # Log the full error error_logger.error( f"Server Error - {request.method} {request.url.path} - " f"{str(exception)} - Request ID: {request_id}\n" f"Traceback:\n{error_traceback}" ) # Create user-friendly error response error_response = { "error": { "type": "server_error", "code": 500, "message": "Internal server error occurred", "request_id": request_id, "timestamp": datetime.now().isoformat(), "path": str(request.url.path), "method": request.method } } # Add debug information in development if self.debug: error_response["debug"] = { "exception": str(exception), "traceback": error_traceback.split('\n'), "headers": dict(request.headers) } return JSONResponse( status_code=500, content=error_response ) def log_performance( self, request: Request, response: Response, duration: float, request_id: str ): """Log performance metrics""" # Log slow requests (> 2 seconds) if duration > 2.0: performance_logger.warning( f"Slow Request - {request.method} {request.url.path} - " f"{duration:.3f}s - Status: {response.status_code} - " f"Request ID: {request_id}" ) else: performance_logger.info( f"Request - {request.method} {request.url.path} - " f"{duration:.3f}s - Status: {response.status_code} - " f"Request ID: {request_id}" ) class ValidationErrorMiddleware(BaseHTTPMiddleware): """Middleware for handling Pydantic validation errors""" async def dispatch(self, request: Request, call_next): try: return await call_next(request) except Exception as e: # Check if it's a validation error if "validation" in str(e).lower() or "pydantic" in str(e).lower(): return self.handle_validation_error(e, request) else: # Let other middleware handle it raise def handle_validation_error(self, exception: Exception, request: Request) -> JSONResponse: """Handle validation errors with detailed feedback""" # Try to extract validation details validation_errors = [] try: # Parse validation error from exception message error_str = str(exception) # Common patterns for validation errors if "field required" in error_str.lower(): validation_errors.append({ "field": "unknown", "message": "Required field is missing", "type": "missing" }) # Add more validation error parsing as needed # This is a simplified version for the MVP except Exception as e: logger.warning(f"Failed to parse validation error detail: {e}") error_response = { "error": { "type": "validation_error", "code": 422, "message": "Invalid request data", "timestamp": datetime.now().isoformat(), "path": str(request.url.path), "method": request.method, "validation_errors": validation_errors } } return JSONResponse( status_code=422, content=error_response ) class CircuitBreakerMiddleware(BaseHTTPMiddleware): """Simple circuit breaker for critical endpoints""" def __init__(self, app, failure_threshold: int = 5, timeout: int = 60): super().__init__(app) self.failure_threshold = failure_threshold self.timeout = timeout self.failure_count = {} self.last_failure_time = {} async def dispatch(self, request: Request, call_next): endpoint = f"{request.method}_{request.url.path}" # Check if circuit is open if self.is_circuit_open(endpoint): return JSONResponse( status_code=503, content={ "error": { "type": "service_unavailable", "message": "Service temporarily unavailable. Please try again later.", "retry_after": self.timeout } } ) try: response = await call_next(request) # Reset failure count on success if endpoint in self.failure_count: del self.failure_count[endpoint] if endpoint in self.last_failure_time: del self.last_failure_time[endpoint] return response except Exception as e: # Increment failure count self.failure_count[endpoint] = self.failure_count.get(endpoint, 0) + 1 self.last_failure_time[endpoint] = datetime.now() # Log circuit breaker activation if self.failure_count[endpoint] >= self.failure_threshold: error_logger.critical( f"Circuit breaker opened for endpoint: {endpoint} - " f"Failure count: {self.failure_count[endpoint]}" ) raise def setup_error_middleware(app, debug: bool = False): """Setup all error handling middleware""" # Add error handling middleware (last to first) app.add_middleware(ValidationErrorMiddleware) app.add_middleware(CircuitBreakerMiddleware) app.add_middleware(ErrorHandlingMiddleware, debug=debug) # Create logs directory if it doesn't exist import os os.makedirs("logs", exist_ok=True)