cloud-reporter/backend/app/scanners/utils.py

"""
Scanner Utilities

Common utilities for AWS resource scanners including retry logic.
"""

import time
import logging
from functools import wraps
from botocore.exceptions import ClientError, BotoCoreError

logger = logging.getLogger(__name__)

# Retry configuration
MAX_RETRIES = 3
BASE_DELAY = 1.0  # seconds
MAX_DELAY = 30.0  # seconds
EXPONENTIAL_BASE = 2.0


def retry_with_backoff(max_retries: int = MAX_RETRIES):
    """
    Decorator for retrying AWS API calls with exponential backoff.
    
    Requirements:
        - 5.5: Retry with exponential backoff up to 3 times
    """
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            last_exception = None
            
            for attempt in range(max_retries):
                try:
                    return func(*args, **kwargs)
                except (ClientError, BotoCoreError) as e:
                    last_exception = e
                    
                    # Check if error is retryable
                    if isinstance(e, ClientError):
                        error_code = e.response.get('Error', {}).get('Code', '')
                        # Non-retryable errors
                        if error_code in ['AccessDenied', 'UnauthorizedAccess', 
                                         'InvalidParameterValue', 'ValidationError']:
                            raise
                    
                    if attempt < max_retries - 1:
                        delay = min(
                            BASE_DELAY * (EXPONENTIAL_BASE ** attempt),
                            MAX_DELAY
                        )
                        logger.warning(
                            f"Retry {attempt + 1}/{max_retries} for {func.__name__} "
                            f"after {delay:.1f}s: {str(e)}"
                        )
                        time.sleep(delay)
                    else:
                        logger.error(
                            f"All {max_retries} retries failed for {func.__name__}: {str(e)}"
                        )
            
            raise last_exception
        return wrapper
    return decorator