| """Langfuse tracing. |
| |
| Tracing is strictly optional: if the Langfuse keys are absent or the service is |
| unreachable, the app logs a warning and keeps working untraced. Observability |
| must never be able to take the application down. |
| """ |
|
|
| import logging |
|
|
| from config import get_settings |
|
|
| logger = logging.getLogger(__name__) |
|
|
| _handler = None |
| _initialised = False |
|
|
|
|
| def _init(): |
| global _handler, _initialised |
| if _initialised: |
| return |
| _initialised = True |
|
|
| settings = get_settings(require_api_key=False) |
| if not settings.tracing_enabled: |
| logger.info("Langfuse tracing disabled (LANGFUSE_PUBLIC_KEY / LANGFUSE_SECRET_KEY not set).") |
| return |
|
|
| try: |
| from langfuse import Langfuse |
| from langfuse.langchain import CallbackHandler |
|
|
| Langfuse( |
| public_key=settings.langfuse_public_key, |
| secret_key=settings.langfuse_secret_key, |
| host=settings.langfuse_host, |
| ) |
| _handler = CallbackHandler() |
| logger.info("Langfuse tracing enabled (%s).", settings.langfuse_host) |
| except Exception as exc: |
| logger.warning("Langfuse tracing unavailable, continuing without it: %s", exc) |
|
|
|
|
| def get_callbacks(): |
| """Callback list for LangChain/LangGraph config. Empty when tracing is off.""" |
| _init() |
| return [_handler] if _handler else [] |
|
|
|
|
| def build_run_config(thread_id, job_description): |
| """Runnable config: checkpoint thread plus Langfuse trace metadata.""" |
| return { |
| "configurable": {"thread_id": thread_id}, |
| "callbacks": get_callbacks(), |
| "run_name": "job_chat_qa", |
| "metadata": { |
| "langfuse_session_id": thread_id, |
| "langfuse_tags": ["job-chat", "with-jd" if job_description else "no-jd"], |
| "jd_loaded": bool(job_description), |
| "jd_words": len(job_description.split()) if job_description else 0, |
| }, |
| } |
|
|
|
|
| def flush(): |
| """Flush pending traces before shutdown.""" |
| if not _handler: |
| return |
| try: |
| from langfuse import get_client |
|
|
| get_client().flush() |
| except Exception as exc: |
| logger.warning("Langfuse flush failed: %s", exc) |
|
|
