backend/app/core/logging.py

"""Structured logging with correlation IDs."""

from __future__ import annotations

import logging
import sys
import uuid
from contextvars import ContextVar

import structlog

correlation_id_var: ContextVar[str] = ContextVar("correlation_id", default="")


def get_correlation_id() -> str:
    cid = correlation_id_var.get()
    if not cid:
        cid = uuid.uuid4().hex[:16]
        correlation_id_var.set(cid)
    return cid


def add_correlation_id(
    logger: structlog.types.WrappedLogger,
    method_name: str,
    event_dict: dict,
) -> dict:
    event_dict["correlation_id"] = get_correlation_id()
    return event_dict


def setup_logging(log_level: str = "INFO", log_format: str = "json") -> None:
    shared_processors: list = [
        structlog.contextvars.merge_contextvars,
        add_correlation_id,
        structlog.stdlib.add_log_level,
        structlog.stdlib.add_logger_name,
        structlog.processors.TimeStamper(fmt="iso"),
        structlog.processors.StackInfoRenderer(),
        structlog.processors.UnicodeDecoder(),
    ]

    if log_format == "json":
        renderer = structlog.processors.JSONRenderer()
    else:
        renderer = structlog.dev.ConsoleRenderer()

    structlog.configure(
        processors=[
            *shared_processors,
            structlog.stdlib.ProcessorFormatter.wrap_for_formatter,
        ],
        logger_factory=structlog.stdlib.LoggerFactory(),
        wrapper_class=structlog.stdlib.BoundLogger,
        cache_logger_on_first_use=True,
    )

    formatter = structlog.stdlib.ProcessorFormatter(
        processors=[
            structlog.stdlib.ProcessorFormatter.remove_processors_meta,
            renderer,
        ],
        foreign_pre_chain=shared_processors,
    )

    handler = logging.StreamHandler(sys.stdout)
    handler.setFormatter(formatter)

    root = logging.getLogger()
    root.handlers.clear()
    root.addHandler(handler)
    root.setLevel(getattr(logging, log_level.upper(), logging.INFO))

    for name in ("uvicorn", "uvicorn.access", "uvicorn.error"):
        lg = logging.getLogger(name)
        lg.handlers.clear()
        lg.propagate = True


def get_logger(name: str | None = None) -> structlog.stdlib.BoundLogger:
    return structlog.get_logger(name)