[router] improve router logs and request id header (#8415)

sgl-router/py_src/sglang_router/launch_router.py

@@ -64,6 +64,8 @@ class RouterArgs:
     # Prometheus configuration
     prometheus_port: Optional[int] = None
     prometheus_host: Optional[str] = None
+    # Request ID headers configuration
+    request_id_headers: Optional[List[str]] = None
 
     @staticmethod
     def add_cli_args(
@@ -255,6 +257,12 @@ class RouterArgs:
             default="127.0.0.1",
             help="Host address to bind the Prometheus metrics server",
         )
+        parser.add_argument(
+            f"--{prefix}request-id-headers",
+            type=str,
+            nargs="*",
+            help="Custom HTTP headers to check for request IDs (e.g., x-request-id x-trace-id). If not specified, uses common defaults.",
+        )
 
     @classmethod
     def from_cli_args(
@@ -313,6 +321,7 @@ class RouterArgs:
             bootstrap_port_annotation="sglang.ai/bootstrap-port",  # Mooncake-specific annotation
             prometheus_port=getattr(args, f"{prefix}prometheus_port", None),
             prometheus_host=getattr(args, f"{prefix}prometheus_host", None),
+            request_id_headers=getattr(args, f"{prefix}request_id_headers", None),
         )
 
     @staticmethod
@@ -481,6 +490,7 @@ def launch_router(args: argparse.Namespace) -> Optional[Router]:
                 if router_args.decode_policy
                 else None
             ),
+            request_id_headers=router_args.request_id_headers,
         )
 
         router.start()

sgl-router/py_src/sglang_router/router.py

@@ -54,6 +54,9 @@ class Router:
             If not specified, uses the main policy. Default: None
         decode_policy: Specific load balancing policy for decode nodes (PD mode only).
             If not specified, uses the main policy. Default: None
+        request_id_headers: List of HTTP headers to check for request IDs. If not specified,
+            uses common defaults: ['x-request-id', 'x-correlation-id', 'x-trace-id', 'request-id'].
+            Example: ['x-my-request-id', 'x-custom-trace-id']. Default: None
     """
 
     def __init__(
@@ -85,6 +88,7 @@ class Router:
         decode_urls: Optional[List[str]] = None,
         prefill_policy: Optional[PolicyType] = None,
         decode_policy: Optional[PolicyType] = None,
+        request_id_headers: Optional[List[str]] = None,
     ):
         if selector is None:
             selector = {}
@@ -121,6 +125,7 @@ class Router:
             decode_urls=decode_urls,
             prefill_policy=prefill_policy,
             decode_policy=decode_policy,
+            request_id_headers=request_id_headers,
         )
 
     def start(self) -> None: