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
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import logging
import subprocess
from pathlib import Path

from components.worker import SGLangWorker
from fastapi import FastAPI
from pydantic import BaseModel

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

logger = logging.getLogger(__name__)


def get_dynamo_run_binary():
    """Find the dynamo-run binary path in SDK or fallback to 'dynamo-run' command."""
    sdk_path = Path(sdk.__file__)
    binary_path = sdk_path.parent / "cli/bin/dynamo-run"
    if not binary_path.exists():
        return "dynamo-run"
    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


@service(
    dynamo={
        "namespace": "dynamo",
    },
    workers=1,
    image=DYNAMO_IMAGE,
    app=FastAPI(title="LLM Example"),
)
class Frontend:
    worker = depends(SGLangWorker)

    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.start_ingress_and_processor()

    def start_ingress_and_processor(self):
        """Starting dynamo-run based ingress and processor"""
        logger.info(
            f"Starting HTTP server and processor on port {self.frontend_config.port}"
        )
        dynamo_run_binary = get_dynamo_run_binary()
        endpoint = f"dyn://{self.frontend_config.endpoint}"

        self.process = subprocess.Popen(
            [
                dynamo_run_binary,
                "in=http",
                f"out={endpoint}",
                "--http-port",
                str(self.frontend_config.port),
            ],
            stdout=None,
            stderr=None,
        )