[Core] Support offline use of local cache for models (#4374)

Signed-off-by: Prashant Gupta <prashantgupta@us.ibm.com>
Co-authored-by: Travis Johnson <tjohnson31415@gmail.com>

vllm/model_executor/model_loader/loader.py

@@ -5,6 +5,7 @@ import os
 from abc import ABC, abstractmethod
 from typing import Any, Dict, Generator, List, Optional, Tuple, Type
 
+import huggingface_hub
 import torch
 from torch import nn
 
@@ -131,7 +132,9 @@ class DefaultModelLoader(BaseModelLoader):
                 model_path = snapshot_download(
                     model_id=model,
                     cache_dir=self.load_config.download_dir,
-                    revision=revision)
+                    local_files_only=huggingface_hub.constants.HF_HUB_OFFLINE,
+                    revision=revision,
+                )
             else:
                 model_path = model
             return model_path