Initiation of Provider on startu FastAPI

[theobouwman]

How can I instantiate this provider on startup:

class TemplateBanditRuntimeProvider(Provider):
    def __init__(self):
        super().__init__(scope=Scope.RUNTIME)
        
    
    @provide(scope=Scope.RUNTIME)
    def template_bandit_runtime_holder(self) -> TemplateBanditRuntime:
        runtime = None
        try:
            runtime = load_runtime_from_wandb()
            logger.info(
                "Loaded template bandit runtime (policy_version=%s) from %s",
                getattr(getattr(runtime, "model", None), "policy_version", "unknown"),
                DEFAULT_LOCAL_MODEL_DIR,
            )
        except Exception as exc:
            logger.warning(
                "Template bandit runtime unavailable at startup; discover/slates will fallback: %s",
                str(exc),
            )

        return runtime

Currently with this setup the template_bandit_runtime_holder only gets called when an API route is called. But I need this object to be available and instantiated on app startup before requests are accepted.

This is a workaround I created:

@asynccontextmanager
async def lifespan(app: FastAPI):
    limiter = anyio.to_thread.current_default_thread_limiter()
    limiter.total_tokens = 1000

    await run_async_upgrade()
    try:
        from common.recpers.flows.template_bandit_pipeline import TemplateBanditRuntime

        runtime = await app.state.dishka_container.get(TemplateBanditRuntime)
        if runtime is None:
            logger.warning(
                "Template bandit runtime warmup completed with fallback runtime at startup.",
            )
        else:
            logger.info(
                "Template bandit runtime preloaded at startup (policy_version=%s).",
                getattr(getattr(runtime, "model", None), "policy_version", "unknown"),
            )
    except Exception as exc:
        logger.warning(
            "Template bandit runtime warmup failed at startup; lazy fallback remains enabled: %s",
            str(exc),
        )

    yield

    await app.state.dishka_container.close()

But I image dishka supports this out of the box?

[Tishka17]

calling dishka_container.get is the right way to do it. We do not have explicit API to disable lazy initialization.

Additionally, in the latest version get_sync was added to async container, so you can get your object (unless it has async dependencies) in application factory.