frontend.py

# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import logging
import subprocess
from pathlib import Path

from components.processor import Processor
from components.worker import VllmWorker
from fastapi import FastAPI
from pydantic import BaseModel

from dynamo import sdk
from dynamo.sdk import async_on_shutdown, depends, service
from dynamo.sdk.lib.config import ServiceConfig
from dynamo.sdk.lib.image import DYNAMO_IMAGE

logger = logging.getLogger(__name__)


def get_http_binary_path():
    """Find the HTTP binary path in SDK or fallback to 'http' command."""
    sdk_path = Path(sdk.__file__)
    binary_path = sdk_path.parent / "cli/bin/http"
    if not binary_path.exists():
        return "http"
    else:
        return str(binary_path)


class FrontendConfig(BaseModel):
    """Configuration for the Frontend service including model and HTTP server settings."""

    served_model_name: str
    endpoint: str
    port: int = 8080


# todo this should be called ApiServer
@service(
    dynamo={
        "enabled": True,
        "namespace": "dynamo",
    },
    resources={"cpu": "10", "memory": "20Gi"},
    workers=1,
    image=DYNAMO_IMAGE,
    app=FastAPI(title="LLM Example"),
)
class Frontend:
    worker = depends(VllmWorker)
    processor = depends(Processor)

    def __init__(self):
        """Initialize Frontend service with HTTP server and model configuration."""
        config = ServiceConfig.get_instance()
        frontend_config = FrontendConfig(**config.get("Frontend", {}))
        self.frontend_config = frontend_config
        self.process = None

        self.setup_model()
        self.start_http_server()

    def setup_model(self):
        """Configure the model for HTTP service using llmctl."""
        subprocess.run(
            [
                "llmctl",
                "http",
                "remove",
                "chat-models",
                self.frontend_config.served_model_name,
            ],
            check=False,
        )
        subprocess.run(
            [
                "llmctl",
                "http",
                "add",
                "chat-models",
                self.frontend_config.served_model_name,
                self.frontend_config.endpoint,
            ],
            check=False,
        )

    def start_http_server(self):
        """Start the HTTP server on the configured port."""
        logger.info("Starting HTTP server")
        http_binary = get_http_binary_path()

        self.process = subprocess.Popen(
            [http_binary, "-p", str(self.frontend_config.port)],
            stdout=None,
            stderr=None,
        )

    @async_on_shutdown
    def cleanup(self):
        """Clean up resources before shutdown."""

        # circusd manages shutdown of http server process, we just need to remove the model using the on_shutdown hook
        subprocess.run(
            [
                "llmctl",
                "http",
                "remove",
                "chat-models",
                self.frontend_config.served_model_name,
            ],
            check=False,
        )