app/core/logger.py

import logging
import sys
import json
from datetime import datetime, timezone


class _JSONFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        log: dict = {
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
        }
        if record.exc_info:
            log["exception"] = self.formatException(record.exc_info)
        extra = {
            k: v
            for k, v in record.__dict__.items()
            if k not in logging.LogRecord.__dict__
            and k
            not in (
                "message",
                "asctime",
                "args",
                "exc_info",
                "exc_text",
                "stack_info",
                "lineno",
                "funcName",
                "created",
                "msecs",
                "relativeCreated",
                "thread",
                "threadName",
                "processName",
                "process",
                "taskName",
            )
        }
        if extra:
            log["context"] = extra
        return json.dumps(log)


def get_logger(name: str) -> logging.Logger:
    logger = logging.getLogger(name)
    logger.propagate = False  # always set — prevents duplicate lines via root logger
    if not logger.handlers:
        handler = logging.StreamHandler(sys.stdout)
        handler.setFormatter(_JSONFormatter())
        logger.addHandler(handler)
        logger.setLevel(logging.INFO)
    return logger