[Frontend] Add Early Validation For Chat Template / Tool Call Parser (#9151)

Signed-off-by: Alex-Brooks <Alex.Brooks@ibm.com>

vllm/entrypoints/openai/api_server.py

@@ -31,7 +31,8 @@ from vllm.engine.multiprocessing.engine import run_mp_engine
 from vllm.engine.protocol import EngineClient
 from vllm.entrypoints.launcher import serve_http
 from vllm.entrypoints.logger import RequestLogger
-from vllm.entrypoints.openai.cli_args import make_arg_parser
+from vllm.entrypoints.openai.cli_args import (make_arg_parser,
+                                              validate_parsed_serve_args)
 # yapf conflicts with isort for this block
 # yapf: disable
 from vllm.entrypoints.openai.protocol import (ChatCompletionRequest,
@@ -577,5 +578,6 @@ if __name__ == "__main__":
         description="vLLM OpenAI-Compatible RESTful API server.")
     parser = make_arg_parser(parser)
     args = parser.parse_args()
+    validate_parsed_serve_args(args)
 
     uvloop.run(run_server(args))

vllm/entrypoints/openai/cli_args.py

@@ -10,6 +10,7 @@ import ssl
 from typing import List, Optional, Sequence, Union
 
 from vllm.engine.arg_utils import AsyncEngineArgs, nullable_str
+from vllm.entrypoints.chat_utils import validate_chat_template
 from vllm.entrypoints.openai.serving_engine import (LoRAModulePath,
                                                     PromptAdapterPath)
 from vllm.entrypoints.openai.tool_parsers import ToolParserManager
@@ -231,6 +232,20 @@ def make_arg_parser(parser: FlexibleArgumentParser) -> FlexibleArgumentParser:
     return parser
 
 
+def validate_parsed_serve_args(args: argparse.Namespace):
+    """Quick checks for model serve args that raise prior to loading."""
+    if hasattr(args, "subparser") and args.subparser != "serve":
+        return
+
+    # Ensure that the chat template is valid; raises if it likely isn't
+    validate_chat_template(args.chat_template)
+
+    # Enable auto tool needs a tool call parser to be valid
+    if args.enable_auto_tool_choice and not args.tool_call_parser:
+        raise TypeError("Error: --enable-auto-tool-choice requires "
+                        "--tool-call-parser")
+
+
 def create_parser_for_docs() -> FlexibleArgumentParser:
     parser_for_docs = FlexibleArgumentParser(
         prog="-m vllm.entrypoints.openai.api_server")