api/logging_config.py

import logging
import os
from pathlib import Path
from logging.handlers import RotatingFileHandler


class IgnoreLogChangeDetectedFilter(logging.Filter):
    def filter(self, record: logging.LogRecord):
        return "Detected file change in" not in record.getMessage()


def setup_logging(format: str = None):
    """
    Configure logging for the application with log rotation.

    Environment variables:
        LOG_LEVEL: Log level (default: INFO)
        LOG_FILE_PATH: Path to log file (default: logs/application.log)
        LOG_MAX_SIZE: Max size in MB before rotating (default: 10MB)
        LOG_BACKUP_COUNT: Number of backup files to keep (default: 5)
        DISABLE_FILE_LOGGING: Set to "true" to disable file logging (default: false)

    Ensures log directory exists, prevents path traversal, and configures
    both rotating file and console handlers. Falls back to console-only logging
    if file logging fails due to permissions.
    """
    # Check if file logging should be disabled
    disable_file_logging = os.environ.get("DISABLE_FILE_LOGGING", "false").lower() == "true"
    
    # Determine log directory and default file path
    base_dir = Path(__file__).parent
    
    # In containerized environments, use /tmp for logs if the default location isn't writable
    try:
        log_dir = base_dir / "logs"
        log_dir.mkdir(parents=True, exist_ok=True)
        default_log_file = log_dir / "application.log"
    except (PermissionError, OSError):
        # Fall back to /tmp for containerized environments
        log_dir = Path("/tmp/deepwiki-logs")
        try:
            log_dir.mkdir(parents=True, exist_ok=True)
            default_log_file = log_dir / "application.log"
        except (PermissionError, OSError):
            # If even /tmp fails, disable file logging
            disable_file_logging = True
            default_log_file = None

    # Get log level from environment - default to WARNING to reduce noise in production
    log_level_str = os.environ.get("LOG_LEVEL", "WARNING").upper()
    log_level = getattr(logging, log_level_str, logging.WARNING)

    # Get log file path (only if file logging is enabled)
    resolved_path = None
    if not disable_file_logging and default_log_file:
        log_file_path = Path(os.environ.get("LOG_FILE_PATH", str(default_log_file)))

        # Secure path check: must be inside logs/ directory
        log_dir_resolved = log_dir.resolve()
        resolved_path = log_file_path.resolve()
        if not str(resolved_path).startswith(str(log_dir_resolved) + os.sep):
            print(f"Warning: LOG_FILE_PATH '{log_file_path}' is outside the trusted log directory '{log_dir_resolved}'. Falling back to console logging.")
            disable_file_logging = True
            resolved_path = None

        # Ensure parent directories exist
        if resolved_path:
            try:
                resolved_path.parent.mkdir(parents=True, exist_ok=True)
            except (PermissionError, OSError):
                print("Warning: Cannot create log directory. Falling back to console logging.")
                disable_file_logging = True
                resolved_path = None

    # Get max log file size (default: 10MB)
    try:
        max_mb = int(os.environ.get("LOG_MAX_SIZE", 10))  # 10MB default
        max_bytes = max_mb * 1024 * 1024
    except (TypeError, ValueError):
        max_bytes = 10 * 1024 * 1024  # fallback to 10MB on error

    # Get backup count (default: 5)
    try:
        backup_count = int(os.environ.get("LOG_BACKUP_COUNT", 5))
    except ValueError:
        backup_count = 5

    # Configure format
    log_format = format or "%(asctime)s - %(levelname)s - %(name)s - %(filename)s:%(lineno)d - %(message)s"

    # Create handlers list
    handlers = []
    
    # Create console handler (always present)
    console_handler = logging.StreamHandler()
    formatter = logging.Formatter(log_format)
    console_handler.setFormatter(formatter)
    console_handler.addFilter(IgnoreLogChangeDetectedFilter())
    handlers.append(console_handler)

    # Create file handler only if file logging is enabled and path is available
    file_handler = None
    if not disable_file_logging and resolved_path:
        try:
            file_handler = RotatingFileHandler(resolved_path, maxBytes=max_bytes, backupCount=backup_count, encoding="utf-8")
            file_handler.setFormatter(formatter)
            file_handler.addFilter(IgnoreLogChangeDetectedFilter())
            handlers.append(file_handler)
        except (PermissionError, OSError) as e:
            print(f"Warning: Cannot create file handler: {e}. Using console logging only.")

    # Apply logging configuration
    logging.basicConfig(level=log_level, handlers=handlers, force=True)

    # Log configuration info
    logger = logging.getLogger(__name__)
    if file_handler and resolved_path:
        logger.debug(
            f"Logging configured: level={log_level_str}, "
            f"file={resolved_path}, max_size={max_bytes} bytes, "
            f"backup_count={backup_count}"
        )
    else:
        logger.debug(f"Logging configured: level={log_level_str}, console only (file logging disabled)")