team-tryouts/app/logging_config.py

"""Structured logging configuration for the Team Tryouts application.

This module configures rotating file handlers for application logs,
with separate files for errors, authentication events, and general logs.
Sensitive data (passwords, tokens) is automatically filtered out.

Usage:
    from logging_config import configure_logging
    configure_logging(app)
"""

import logging
import os
from logging.handlers import RotatingFileHandler
import re


class SensitiveDataFilter(logging.Filter):
    """Logging filter that redacts sensitive information from log messages.
    
    Filters out: passwords, API keys, session tokens, and other secrets
    that might accidentally be logged.
    """

    # Patterns to redact
    SENSITIVE_PATTERNS = [
        (re.compile(r'(?:password|passwd|secret|token|api[_-]?key)\s*[:=]\s*[^\s,;)]+', re.IGNORECASE), '[REDACTED]'),
        (re.compile(r'(?:password|passwd|secret|token|api[_-]?key)\s*[:=]\s*"[^"]*"', re.IGNORECASE), lambda m: m.group(0).split('=')[0] + '="[REDACTED]"'),
        (re.compile(r'Authorization[:\s]+[^\s]+', re.IGNORECASE), 'Authorization: [REDACTED]'),
        (re.compile(r'Bearer\s+[^\s]+', re.IGNORECASE), 'Bearer [REDACTED]'),
    ]

    def filter(self, record):
        """Apply redaction to the log record's message.
        
        Args:
            record: The log record to filter.
            
        Returns:
            bool: Always True (never drops records, only redacts).
        """
        if hasattr(record, 'msg') and isinstance(record.msg, str):
            msg = record.msg
            for pattern, replacement in self.SENSITIVE_PATTERNS:
                if callable(replacement):
                    msg = pattern.sub(replacement, msg)
                else:
                    msg = pattern.sub(replacement, msg)
            record.msg = msg
        return True


def configure_logging(app):
    """Configure structured logging for the Flask application.
    
    Sets up three rotating file handlers:
        - errors.log: ERROR and CRITICAL level messages
        - auth.log: Authentication-related events (INFO and above)
        - app.log: All application logs (DEBUG and above, configurable)
    
    Also configures console output for development.
    
    Args:
        app: The Flask application instance to configure logging for.
    """
    log_dir = os.path.join(os.getcwd(), 'logs')
    os.makedirs(log_dir, exist_ok=True)

    # Remove default Flask handlers to avoid duplicate logging
    app.logger.handlers.clear()

    # Set base log level from environment (default: INFO)
    log_level_name = os.getenv('LOG_LEVEL', 'INFO').upper()
    log_level = getattr(logging, log_level_name, logging.INFO)
    app.logger.setLevel(log_level)

    # Create the sensitive data filter
    sensitive_filter = SensitiveDataFilter()

    # Formatter with timestamp, level, module, and message
    formatter = logging.Formatter(
        '[%(asctime)s] %(levelname)s [%(name)s:%(lineno)d] %(message)s',
        datefmt='%Y-%m-%d %H:%M:%S'
    )

    # -------------------------------------------------------------------------
    # 1. Error Log Handler
    # -------------------------------------------------------------------------
    error_handler = RotatingFileHandler(
        os.path.join(log_dir, 'errors.log'),
        maxBytes=10 * 1024 * 1024,  # 10 MB
        backupCount=10
    )
    error_handler.setLevel(logging.ERROR)
    error_handler.setFormatter(formatter)
    error_handler.addFilter(sensitive_filter)
    app.logger.addHandler(error_handler)

    # -------------------------------------------------------------------------
    # 2. Authentication Log Handler
    # -------------------------------------------------------------------------
    auth_handler = RotatingFileHandler(
        os.path.join(log_dir, 'auth.log'),
        maxBytes=10 * 1024 * 1024,  # 10 MB
        backupCount=5
    )
    auth_handler.setLevel(logging.INFO)
    auth_handler.setFormatter(formatter)
    auth_handler.addFilter(sensitive_filter)

    # Create a named logger specifically for auth events
    auth_logger = logging.getLogger('team_tryouts.auth')
    auth_logger.setLevel(logging.INFO)
    auth_logger.addHandler(auth_handler)
    auth_logger.propagate = False  # Don't double-log to root

    # -------------------------------------------------------------------------
    # 3. Application Log Handler (general)
    # -------------------------------------------------------------------------
    app_handler = RotatingFileHandler(
        os.path.join(log_dir, 'app.log'),
        maxBytes=10 * 1024 * 1024,  # 10 MB
        backupCount=10
    )
    app_handler.setLevel(log_level)
    app_handler.setFormatter(formatter)
    app_handler.addFilter(sensitive_filter)
    app.logger.addHandler(app_handler)

    # -------------------------------------------------------------------------
    # 4. Console Handler (for development)
    # -------------------------------------------------------------------------
    if os.getenv('FLASK_DEBUG', 'false').lower() == 'true':
        console_handler = logging.StreamHandler()
        console_handler.setLevel(logging.DEBUG)
        console_handler.setFormatter(formatter)
        console_handler.addFilter(sensitive_filter)
        app.logger.addHandler(console_handler)

    # Log startup information
    app.logger.info('Logging configured - Level: %s, Log directory: %s', log_level_name, log_dir)
    app.logger.info('Application startup')

    return app.logger


# Module-level auth logger factory
def get_auth_logger():
    """Get the authentication event logger.
    
    Returns:
        logging.Logger: Logger for authentication events.
    """
    return logging.getLogger('team_tryouts.auth')