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08f1adc 2461f82 08f1adc 2461f82 08f1adc 2461f82 08f1adc 2461f82 08f1adc | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | """FastAPI application entrypoint.
Run locally with::
uvicorn --app-dir backend app.main:app --host 0.0.0.0 --port 8000 --reload
Lifespan order:
1. Load YAML ``AppConfig`` (research-side hyperparameters).
2. Load weights + tokenizer into a ``CaptionPredictor`` singleton.
3. Optionally warmup so the first request doesn't pay TF's lazy build cost.
4. Wrap the predictor in a ``PredictorService`` and stash on app state.
The singleton lives on ``app.state.predictor_service``; routes pull it
through a ``Depends`` so tests can override the dependency cleanly.
"""
from __future__ import annotations
from collections.abc import AsyncIterator
from contextlib import asynccontextmanager
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from app.api.routes import router
from app.core.config import BackendSettings, get_backend_settings
from app.core.logging import RequestContextMiddleware, configure_app_logging
from app.services.predictor_service import PredictorService
from app.services.weights_loader import resolve_weights
from captioning.config import load_config
from captioning.config.schema import AppConfig
from captioning.inference import CaptionPredictor
from captioning.utils import get_logger
log = get_logger(__name__)
@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncIterator[None]:
"""Load the predictor at startup, release it at shutdown."""
settings: BackendSettings = app.state.backend_settings
config: AppConfig = app.state.app_config
weights_path, tokenizer_dir = resolve_weights(settings)
log.info(
"predictor_loading",
weights=str(weights_path),
tokenizer_dir=str(tokenizer_dir),
model_version=settings.model_version,
)
predictor = CaptionPredictor.from_artifacts(
weights_path=weights_path,
tokenizer_dir=tokenizer_dir,
config=config,
)
if settings.warmup:
predictor.warmup()
app.state.predictor_service = PredictorService(
predictor=predictor,
model_version=settings.model_version,
max_upload_bytes=config.serve.max_upload_bytes,
)
log.info("predictor_ready", model_version=settings.model_version)
try:
yield
finally:
app.state.predictor_service = None
log.info("predictor_unloaded")
def create_app() -> FastAPI:
"""Build the FastAPI app. Factory form so tests can construct fresh apps."""
configure_app_logging()
settings = get_backend_settings()
config = load_config(settings.config_path)
app = FastAPI(
title="Image Captioning API",
version=settings.api_version,
description=(
"Production-grade inference service for the IEEE-published "
"CNN+Transformer image captioning model."
),
lifespan=lifespan,
)
app.state.backend_settings = settings
app.state.app_config = config
app.state.predictor_service = None
app.add_middleware(
CORSMiddleware,
allow_origins=config.serve.cors_allowed_origins,
allow_methods=["GET", "POST", "OPTIONS"],
allow_headers=["*"],
allow_credentials=False,
)
app.add_middleware(RequestContextMiddleware)
app.include_router(router)
return app
app = create_app()
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