python-observability-patterns

# Python Observability Patterns Logging, metrics, and tracing for production applications. ## Structured Logging with structlog ```python import structlog # Configure structlog structlog.configure( processors=[ structlog.contextvars.merge_contextvars, structlog.processors.add_log_level, structlog.processors.TimeStamper(fmt="iso"), structlog.processors.JSONRenderer(), ], wrapper_class=structlog.make_filtering_bound_logger(logging.INFO), context_class=dict, logger_factory=structlog.PrintLoggerFactory(), ) logger = structlog.get_logger() # Usage logger.info("user_created", user_id=123, email="test@example.com") # Output: {"event": "user_created", "user_id": 123, "email": "test@example.com", "level": "info", "timestamp": "2024-01-15T10:00:00Z"} ``` ## Request Context Propagation ```python import structlog from contextvars import ContextVar from uuid import uuid4 request_id_var: ContextVar[str] = ContextVar("request_id", default="") def bind_request_context(request_id: str | None = None): """Bind request ID to logging context.""" rid = request_id or str(uuid4()) request_id_var.set(rid) structlog.contextvars.bind_contextvars(request_id=rid) return rid # FastAPI middleware @app.middleware("http") async def request_context_middleware(request, call_next): request_id = request.headers.get("X-Request-ID") or str(uuid4()) bind_request_context(request_id) response = await call_next(request) ...