Logging

# Python 구조화된 로깅 설정 (structlog)
import structlog
import logging

# 구조화된 로거 설정
structlog.configure(
    processors=[
        structlog.stdlib.filter_by_level,
        structlog.stdlib.add_logger_name,
        structlog.stdlib.add_log_level,
        structlog.processors.TimeStamper(fmt="iso"),
        structlog.processors.StackInfoRenderer(),
        structlog.processors.format_exc_info,
        structlog.processors.UnicodeDecoder(),
        # JSON 출력 (프로덕션)
        structlog.processors.JSONRenderer()
    ],
    wrapper_class=structlog.stdlib.BoundLogger,
    context_class=dict,
    logger_factory=structlog.stdlib.LoggerFactory(),
    cache_logger_on_first_use=True,
)

log = structlog.get_logger()

# 컨텍스트와 함께 로깅
def process_order(order_id: str, user_id: str):
    # 요청별 컨텍스트 바인딩
    log_ctx = log.bind(
        order_id=order_id,
        user_id=user_id,
        trace_id=get_trace_id()  # 분산 추적 ID
    )

    log_ctx.info("order_processing_started")

    try:
        result = payment_service.charge(order_id)
        log_ctx.info(
            "payment_completed",
            amount=result.amount,
            currency=result.currency
        )
    except PaymentError as e:
        log_ctx.error(
            "payment_failed",
            error_code=e.code,
            error_message=str(e)
        )
        raise

// 구조화된 로그 출력 예시 (JSON Lines)
{"timestamp": "2024-01-15T09:30:00.123Z", "level": "info", "event": "order_processing_started", "order_id": "ORD-12345", "user_id": "USR-789", "trace_id": "abc123", "service": "order-api"}
{"timestamp": "2024-01-15T09:30:00.456Z", "level": "info", "event": "payment_completed", "order_id": "ORD-12345", "user_id": "USR-789", "trace_id": "abc123", "amount": 59900, "currency": "KRW"}
{"timestamp": "2024-01-15T09:30:01.789Z", "level": "error", "event": "payment_failed", "order_id": "ORD-12346", "user_id": "USR-790", "trace_id": "def456", "error_code": "INSUFFICIENT_FUNDS", "error_message": "Card declined"}

// Node.js 구조화된 로깅 (Pino)
const pino = require('pino');
const logger = pino({
  level: process.env.LOG_LEVEL || 'info',
  formatters: {
    level: (label) => ({ level: label })
  },
  timestamp: pino.stdTimeFunctions.isoTime
});

// 자식 로거로 컨텍스트 추가
const reqLogger = logger.child({
  requestId: req.id,
  userId: req.user?.id
});
reqLogger.info({ path: req.path }, 'request received');