Add logging and add mongodb connection pool

app/logger.py

@@ -0,0 +1,102 @@
+"""
+Centralized logging configuration using Loguru.
+
+Outputs structured JSON to stdout (INFO/WARNING) and stderr (ERROR/CRITICAL).
+Designed for Docker + Grafana Loki / Promtail.
+
+Usage:
+    from logger import logger, setup_logging
+
+    setup_logging()          # call once at application entry point
+    logger.info("message")
+"""
+
+import os
+import sys
+import logging
+from dotenv import load_dotenv
+from loguru import logger
+
+
+def get_log_level() -> str:
+    """Reads LOG_LEVEL or log_level from .env or environment, defaults to 'INFO'."""
+    load_dotenv()
+    level = os.getenv("LOG_LEVEL") or os.getenv("log_level") or "INFO"
+    return level.strip().upper()
+
+
+# ── Stdout / stderr filters ───────────────────────────────────────────────────
+
+def _stdout_filter(record: dict) -> bool:
+    """Pass DEBUG / INFO / WARNING to stdout."""
+    return record["level"].no < logging.ERROR
+
+
+def _stderr_filter(record: dict) -> bool:
+    """Pass ERROR / CRITICAL to stderr."""
+    return record["level"].no >= logging.ERROR
+
+
+# ── Stdlib → Loguru bridge ────────────────────────────────────────────────────
+
+class InterceptHandler(logging.Handler):
+    """Redirect all stdlib logging calls into Loguru."""
+
+    def emit(self, record: logging.LogRecord) -> None:
+        try:
+            level = logger.level(record.levelname).name
+        except ValueError:
+            level = record.levelno
+
+        frame, depth = sys._getframe(6), 6
+        while frame and frame.f_code.co_filename == logging.__file__:
+            frame = frame.f_back
+            depth += 1
+
+        logger.opt(depth=depth, exception=record.exc_info).log(
+            level, record.getMessage()
+        )
+
+
+# ── Public setup function ─────────────────────────────────────────────────────
+
+def setup_logging(level: str | None = None) -> None:
+    """
+    Configure Loguru sinks and intercept all stdlib loggers.
+    Call once at the very start of the application entry point.
+    """
+    if not level:
+        level = get_log_level()
+    else:
+        level = level.strip().upper()
+
+    logger.remove()  # remove default sink
+
+    common: dict = {
+        "level": level,
+        "serialize": True,   # JSON output
+        "backtrace": False,
+        "diagnose": False,
+    }
+
+    # stdout — DEBUG / INFO / WARNING
+    logger.add(sys.stdout, filter=_stdout_filter, **common)
+
+    # stderr — ERROR / CRITICAL
+    logger.add(sys.stderr, filter=_stderr_filter, **{**common, "level": "ERROR"})
+
+    # Redirect all stdlib loggers (uvicorn, motor, aiogram, aio_pika …)
+    logging.basicConfig(handlers=[InterceptHandler()], level=0, force=True)
+
+    # Suppress noisy third-party loggers — we handle HTTP access via middleware
+    _quiet = {
+        "uvicorn.access": logging.WARNING,  # replaced by our middleware
+        "motor":          logging.WARNING,
+        "aio_pika":       logging.WARNING,
+        "aiormq":         logging.WARNING,
+    }
+    for name, lvl in _quiet.items():
+        _lib_logger = logging.getLogger(name)
+        _lib_logger.handlers = [InterceptHandler()]
+        _lib_logger.setLevel(lvl)
+        _lib_logger.propagate = False