[grpc] Support gRPC server entrypoint (#30190)

Signed-off-by: Chang Su <chang.s.su@oracle.com>
Signed-off-by: njhill <nickhill123@gmail.com>
Signed-off-by: Nick Hill <nickhill123@gmail.com>
Co-authored-by: njhill <nickhill123@gmail.com>
Co-authored-by: Simon Mo <simon.mo@hey.com>

setup.py

@@ -18,6 +18,7 @@ import torch
 from packaging.version import Version, parse
 from setuptools import Extension, setup
 from setuptools.command.build_ext import build_ext
+from setuptools.command.build_py import build_py
 from setuptools_scm import get_version
 from torch.utils.cpp_extension import CUDA_HOME, ROCM_HOME
 
@@ -79,6 +80,73 @@ def is_freethreaded():
     return bool(sysconfig.get_config_var("Py_GIL_DISABLED"))
 
 
+def compile_grpc_protos():
+    """Compile gRPC protobuf definitions during build.
+
+    This generates *_pb2.py, *_pb2_grpc.py, and *_pb2.pyi files from
+    the vllm_engine.proto definition.
+    """
+    try:
+        from grpc_tools import protoc
+    except ImportError:
+        logger.warning(
+            "grpcio-tools not installed, skipping gRPC proto compilation. "
+            "gRPC server functionality will not be available."
+        )
+        return False
+
+    proto_file = ROOT_DIR / "vllm" / "grpc" / "vllm_engine.proto"
+    if not proto_file.exists():
+        logger.warning("Proto file not found at %s, skipping compilation", proto_file)
+        return False
+
+    logger.info("Compiling gRPC protobuf: %s", proto_file)
+
+    result = protoc.main(
+        [
+            "grpc_tools.protoc",
+            f"--proto_path={ROOT_DIR}",
+            f"--python_out={ROOT_DIR}",
+            f"--grpc_python_out={ROOT_DIR}",
+            f"--pyi_out={ROOT_DIR}",
+            str(proto_file),
+        ]
+    )
+
+    if result != 0:
+        logger.error("protoc failed with exit code %s", result)
+        return False
+
+    # Add SPDX headers and mypy ignore to generated files
+    spdx_header = (
+        "# SPDX-License-Identifier: Apache-2.0\n"
+        "# SPDX-FileCopyrightText: Copyright contributors to the vLLM project\n"
+        "# mypy: ignore-errors\n"
+    )
+
+    grpc_dir = ROOT_DIR / "vllm" / "grpc"
+    for generated_file in [
+        grpc_dir / "vllm_engine_pb2.py",
+        grpc_dir / "vllm_engine_pb2_grpc.py",
+        grpc_dir / "vllm_engine_pb2.pyi",
+    ]:
+        if generated_file.exists():
+            content = generated_file.read_text()
+            if not content.startswith("# SPDX-License-Identifier"):
+                generated_file.write_text(spdx_header + content)
+
+    logger.info("gRPC protobuf compilation successful")
+    return True
+
+
+class BuildPyAndGenerateGrpc(build_py):
+    """Build Python modules and generate gRPC stubs from proto files."""
+
+    def run(self):
+        compile_grpc_protos()
+        super().run()
+
+
 class CMakeExtension(Extension):
     def __init__(self, name: str, cmake_lists_dir: str = ".", **kwa) -> None:
         super().__init__(name, sources=[], py_limited_api=not is_freethreaded(), **kwa)
@@ -882,12 +950,13 @@ if _no_device():
     ext_modules = []
 
 if not ext_modules:
-    cmdclass = {}
+    cmdclass = {"build_py": BuildPyAndGenerateGrpc}
 else:
     cmdclass = {
         "build_ext": precompiled_build_ext
         if envs.VLLM_USE_PRECOMPILED
-        else cmake_build_ext
+        else cmake_build_ext,
+        "build_py": BuildPyAndGenerateGrpc,
     }
 
 setup(