Add trace_id to Logs for Enhanced Traceability (#265)

* Add trace-id to logs for tracing of logs across a request cycle

* add logs trace-id to langfuse traces

Author: avirajsingh7

backend/app/core/langfuse/langfuse.py

@@ -1,6 +1,7 @@
 import uuid
 import logging
 from typing import Any, Dict, Optional
+from asgi_correlation_id import correlation_id
 
 from langfuse import Langfuse
 from langfuse.client import StatefulGenerationClient, StatefulTraceClient
@@ -55,10 +56,13 @@ def start_trace(
         input: Dict[str, Any],
         metadata: Optional[Dict[str, Any]] = None,
     ):
+        metadata = metadata or {}
+        metadata["request_id"] = correlation_id.get() or "N/A"
+
         self.trace = self.langfuse.trace(
             name=name,
             input=input,
-            metadata=metadata or {},
+            metadata=metadata,
             session_id=self.session_id,
         )
 

backend/app/core/logger.py

@@ -1,6 +1,7 @@
 import logging
 import os
 from logging.handlers import RotatingFileHandler
+from asgi_correlation_id import correlation_id
 from app.core.config import settings
 
 LOG_DIR = settings.LOG_DIR
@@ -9,7 +10,16 @@
 LOG_FILE_PATH = os.path.join(LOG_DIR, "app.log")
 
 LOGGING_LEVEL = logging.INFO
-LOGGING_FORMAT = "%(asctime)s - %(levelname)s - %(name)s - %(message)s"
+LOGGING_FORMAT = (
+    "%(asctime)s - [%(correlation_id)s] - %(levelname)s - %(name)s - %(message)s"
+)
+
+
+class CorrelationIdFilter(logging.Filter):
+    def filter(self, record: logging.LogRecord) -> bool:
+        record.correlation_id = correlation_id.get() or "N/A"
+        return True
+
 
 # Create root logger
 logger = logging.getLogger()
@@ -21,11 +31,13 @@
 # Stream handler (console)
 stream_handler = logging.StreamHandler()
 stream_handler.setFormatter(formatter)
+stream_handler.addFilter(CorrelationIdFilter())
 logger.addHandler(stream_handler)
 
 # Rotating file handler
 file_handler = RotatingFileHandler(
     LOG_FILE_PATH, maxBytes=10 * 1024 * 1024, backupCount=5
 )
 file_handler.setFormatter(formatter)
+file_handler.addFilter(CorrelationIdFilter())
 logger.addHandler(file_handler)

backend/app/main.py

@@ -1,8 +1,7 @@
 import sentry_sdk
-
 from fastapi import FastAPI
 from fastapi.routing import APIRoute
-
+from asgi_correlation_id.middleware import CorrelationIdMiddleware
 from app.api.main import api_router
 from app.core.config import settings
 import app.core.logger
@@ -24,6 +23,7 @@ def custom_generate_unique_id(route: APIRoute) -> str:
 )
 
 app.middleware("http")(http_request_logger)
+app.add_middleware(CorrelationIdMiddleware)
 
 app.include_router(api_router, prefix=settings.API_V1_STR)
 

backend/pyproject.toml

@@ -28,6 +28,7 @@ dependencies = [
     "pre-commit>=3.8.0",
     "openai_responses",
     "langfuse>=2.60.3",
+    "asgi-correlation-id>=4.3.4",
 ]
 
 [tool.uv]