FIX Loading adapter honors offline mode

[BenjaminBossan]

HF_HUB_OFFLINE=1 was not honored when trying to load an adapter. This is now fixed.

Resolves huggingface/transformers#31700.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[BenjaminBossan]

I wanted to add a test for this but for some reason, it does not work. Inside the test, I set os.environ["HF_HUB_OFFLINE_MODE"] = "1" but the adapter is still downloaded fine, as if the env var were not set. I even tried to start a new subprocess with the adjusted env var but this still had no effect. Not sure what the issue is.

Running this test manually works:

def test_load_from_hub_then_offline_model():
    peft_model_id = "peft-internal-testing/gpt2-lora-random"
    base_model = AutoModelForCausalLM.from_pretrained("gpt2")
    PeftModel.from_pretrained(base_model, peft_model_id)

Without the fix, this test fails with HF_HUB_OFFLINE_MODE=1 and with the fix it passes (run it without first to ensure that the adapter is available locally).

[Wauplin]

Hi @BenjaminBossan, HF_HUB_OFFLINE is evaluated only once at runtime. This is why updating the environment variable for the test does not work. What we do in huggingface_hub is to define a offline context manager (here) and use it like this. Example:

        for offline_mode in OfflineSimulationMode:
            with offline(mode=offline_mode):
                with SoftTemporaryDirectory() as tmpdir:
                    with self.assertRaises(LocalEntryNotFoundError):
                        snapshot_download(self.repo_id, cache_dir=tmpdir)

[Wauplin]

Suggested change

	elif os.environ.get("HF_HUB_OFFLINE", 0) in {"1", "ON", "YES", "TRUE"}: # same check as in hfh
	elif huggingface_hub.constants.HF_HUB_OFFLINE:

Better to let huggingface_hub handle the env variable parsing. Suggestion needs an additional import.

[BenjaminBossan]

What we do in huggingface_hub is to define a offline context manager

Thanks for this. It looks like I cannot import this, as it's not part of the src, right? So I would have to copy the whole function over to PEFT to use the context, or is there an easier way?

[Wauplin]

Thanks for this. It looks like I cannot import this, as it's not part of the src, right? So I would have to copy the whole function over to PEFT to use the context, or is there an easier way?

There is unfortunately no easy way to import this no 😕 Best way is to duplicate it, though I'd recommend to copy a simplified version of it with only

        with patch("huggingface_hub.constants.HF_HUB_OFFLINE", True):
            reset_sessions()
            yield
        reset_sessions()

You don't need to test the cases with ConnectionError or TimeoutError for this PR.

[BenjaminBossan]

Thanks, this works perfectly!

[Wauplin]

Looks good to me! Thanks for adding the small test :)