app/core/logging.py

"""
Production-standard logging configuration for AUTH Microservice.
Provides structured logging with file rotation, JSON formatting, and proper log levels.
"""
import logging
import logging.handlers
import json
import sys
from pathlib import Path
from datetime import datetime
from typing import Optional
from app.core.config import settings


class JSONFormatter(logging.Formatter):
    """Custom JSON formatter for structured logging."""
    
    def _serialize_value(self, value):
        """Convert non-serializable values to strings."""
        try:
            json.dumps(value)
            return value
        except (TypeError, ValueError):
            return str(value)
    
    def format(self, record: logging.LogRecord) -> str:
        """Format log record as JSON."""
        log_data = {
            "timestamp": datetime.utcnow().isoformat(),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
            "module": record.module,
            "function": record.funcName,
            "line": record.lineno,
        }
        
        # Add exception info if present
        if record.exc_info:
            log_data["exception"] = self.formatException(record.exc_info)
        
        # Add extra fields from the record
        if hasattr(record, "extra") and record.extra:
            for key, value in record.extra.items():
                log_data[key] = self._serialize_value(value)
        
        # Add extra context from LogRecord attributes
        for key, value in record.__dict__.items():
            if key not in [
                "name", "msg", "args", "created", "filename", "funcName",
                "levelname", "levelno", "lineno", "module", "msecs",
                "message", "pathname", "process", "processName", "relativeCreated",
                "thread", "threadName", "exc_info", "exc_text", "stack_info",
                "getMessage", "extra"
            ]:
                if not key.startswith("_"):
                    log_data[key] = self._serialize_value(value)
        
        return json.dumps(log_data, default=str)


class StructuredLogger:
    """Structured logger wrapper for production use."""
    
    def __init__(self, name: str):
        self.logger = logging.getLogger(name)
    
    def _log(
        self,
        level: int,
        message: str,
        extra: Optional[dict] = None,
        exc_info: bool = False,
    ):
        """Internal logging method with extra context."""
        if extra:
            self.logger.log(level, message, extra={"extra": extra}, exc_info=exc_info)
        else:
            self.logger.log(level, message, exc_info=exc_info)
    
    def debug(self, message: str, extra: Optional[dict] = None):
        """Log debug message."""
        self._log(logging.DEBUG, message, extra)
    
    def info(self, message: str, extra: Optional[dict] = None):
        """Log info message."""
        self._log(logging.INFO, message, extra)
    
    def warning(self, message: str, extra: Optional[dict] = None):
        """Log warning message."""
        self._log(logging.WARNING, message, extra)
    
    def error(self, message: str, extra: Optional[dict] = None, exc_info: bool = False):
        """Log error message."""
        self._log(logging.ERROR, message, extra, exc_info)
    
    def critical(self, message: str, extra: Optional[dict] = None, exc_info: bool = False):
        """Log critical message."""
        self._log(logging.CRITICAL, message, extra, exc_info)


def setup_logging(
    log_level: str = "INFO",
    log_dir: str = "logs",
    console_json: bool = False,
) -> None:
    """
    Configure production-standard logging.
    
    Args:
        log_level: Logging level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
        log_dir: Directory for log files
        console_json: Whether to output JSON to console (default: human-readable)
    """
    
    # Create logs directory
    log_path = Path(log_dir)
    log_path.mkdir(exist_ok=True)
    
    # Get root logger
    root_logger = logging.getLogger()
    root_logger.setLevel(getattr(logging, log_level.upper()))
    
    # Remove existing handlers
    root_logger.handlers = []
    
    # Create formatters
    console_formatter = (
        JSONFormatter() if console_json
        else logging.Formatter(
            fmt='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
            datefmt='%Y-%m-%d %H:%M:%S'
        )
    )
    
    json_formatter = JSONFormatter()
    
    # Console Handler (stderr)
    console_handler = logging.StreamHandler(sys.stderr)
    console_handler.setLevel(getattr(logging, log_level.upper()))
    console_handler.setFormatter(console_formatter)
    root_logger.addHandler(console_handler)
    
    # File Handler - All logs (JSON format)
    file_handler = logging.handlers.RotatingFileHandler(
        filename=log_path / "app.log",
        maxBytes=10 * 1024 * 1024,  # 10MB
        backupCount=10,
        encoding="utf-8"
    )
    file_handler.setLevel(logging.DEBUG)
    file_handler.setFormatter(json_formatter)
    root_logger.addHandler(file_handler)
    
    # File Handler - Info and above (JSON format)
    info_handler = logging.handlers.RotatingFileHandler(
        filename=log_path / "app_info.log",
        maxBytes=10 * 1024 * 1024,  # 10MB
        backupCount=5,
        encoding="utf-8"
    )
    info_handler.setLevel(logging.INFO)
    info_handler.setFormatter(json_formatter)
    root_logger.addHandler(info_handler)
    
    # File Handler - Errors only (JSON format)
    error_handler = logging.handlers.RotatingFileHandler(
        filename=log_path / "app_errors.log",
        maxBytes=10 * 1024 * 1024,  # 10MB
        backupCount=10,
        encoding="utf-8"
    )
    error_handler.setLevel(logging.ERROR)
    error_handler.setFormatter(json_formatter)
    root_logger.addHandler(error_handler)
    
    # Reduce noisy loggers
    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
    logging.getLogger("motor").setLevel(logging.WARNING)
    logging.getLogger("asyncio").setLevel(logging.WARNING)
    
    # Log startup message
    root_logger.info(
        "Logging configured",
        extra={
            "log_level": log_level,
            "log_dir": str(log_path),
            "handlers": [type(h).__name__ for h in root_logger.handlers]
        }
    )


def get_logger(name: str) -> StructuredLogger:
    """
    Get a structured logger instance.
    
    Args:
        name: Logger name (typically __name__)
        
    Returns:
        StructuredLogger: Configured logger instance
    """
    return StructuredLogger(name)