[router] Replace print with logger (#2183)

rust/py_src/sglang_router/launch_router.py

@@ -1,5 +1,6 @@
 import argparse
 import dataclasses
+import logging
 import sys
 from typing import List, Optional
 
@@ -7,6 +8,22 @@ from sglang_router import Router
 from sglang_router_rs import PolicyType
 
 
+def setup_logger():
+    logger = logging.getLogger("router")
+    logger.setLevel(logging.INFO)
+
+    formatter = logging.Formatter(
+        "[Router (Python)] %(asctime)s - %(levelname)s - %(message)s",
+        datefmt="%Y-%m-%d %H:%M:%S",
+    )
+
+    handler = logging.StreamHandler()
+    handler.setFormatter(formatter)
+    logger.addHandler(handler)
+
+    return logger
+
+
 @dataclasses.dataclass
 class RouterArgs:
     # Worker configuration
@@ -21,6 +38,7 @@ class RouterArgs:
     balance_rel_threshold: float = 1.0001
     eviction_interval: int = 60
     max_tree_size: int = 2**24
+    verbose: bool = False
 
     @staticmethod
     def add_cli_args(
@@ -98,6 +116,11 @@ class RouterArgs:
             default=RouterArgs.max_tree_size,
             help="Maximum size of the approximation tree for cache-aware routing",
         )
+        parser.add_argument(
+            f"--{prefix}verbose",
+            action="store_true",
+            help="Enable verbose logging",
+        )
 
     @classmethod
     def from_cli_args(
@@ -121,6 +144,7 @@ class RouterArgs:
             balance_rel_threshold=getattr(args, f"{prefix}balance_rel_threshold"),
             eviction_interval=getattr(args, f"{prefix}eviction_interval"),
             max_tree_size=getattr(args, f"{prefix}max_tree_size"),
+            verbose=getattr(args, f"{prefix}verbose", False),
         )
 
 
@@ -145,6 +169,7 @@ def launch_router(args: argparse.Namespace) -> Optional[Router]:
     Returns:
         Router instance if successful, None if failed
     """
+    logger = logging.getLogger("router")
     try:
         # Convert to RouterArgs if needed
         if not isinstance(args, RouterArgs):
@@ -162,13 +187,14 @@ def launch_router(args: argparse.Namespace) -> Optional[Router]:
             balance_rel_threshold=router_args.balance_rel_threshold,
             eviction_interval_secs=router_args.eviction_interval,
             max_tree_size=router_args.max_tree_size,
+            verbose=router_args.verbose,
         )
 
         router.start()
         return router
 
     except Exception as e:
-        print(f"Error starting router: {e}", file=sys.stderr)
+        logger.error(f"Error starting router: {e}", file=sys.stderr)
         return None
 
 
@@ -202,6 +228,7 @@ Examples:
 
 
 def main() -> None:
+    logger = setup_logger()
     router_args = parse_router_args(sys.argv[1:])
     router = launch_router(router_args)