retrieval_service/app/app.py

# Copyright 2023 Google LLC
#
# 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
#
#     https://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.

from contextlib import asynccontextmanager
from ipaddress import IPv4Address, IPv6Address
from typing import Optional

import yaml
from fastapi import FastAPI
from langchain_google_vertexai import VertexAIEmbeddings
from pydantic import BaseModel

import datastore

from .routes import routes

EMBEDDING_MODEL_NAME = "text-embedding-005"


class AppConfig(BaseModel):
    host: IPv4Address | IPv6Address = IPv4Address("127.0.0.1")
    port: int = 8080
    datastore: datastore.Config
    clientId: Optional[str] = None


def parse_config(path: str) -> AppConfig:
    with open(path, "r") as file:
        config = yaml.safe_load(file)
    return AppConfig(**config)


# gen_init is a wrapper to initialize the datastore during app startup
def gen_init(cfg: AppConfig):
    async def initialize_datastore(app: FastAPI):
        app.state.datastore = await datastore.create(cfg.datastore)
        app.state.embed_service = VertexAIEmbeddings(model_name=EMBEDDING_MODEL_NAME)
        yield
        await app.state.datastore.close()

    return asynccontextmanager(initialize_datastore)


def init_app(cfg: AppConfig) -> FastAPI:
    app = FastAPI(lifespan=gen_init(cfg))
    app.state.client_id = cfg.clientId
    app.include_router(routes)
    return app