Implement dry run mode in download CLI

docs/source/en/guides/cli.md

@@ -254,6 +254,46 @@ A `.cache/huggingface/` folder is created at the root of your local directory co
 fuyu/model-00001-of-00002.safetensors
 ```
 
+### Dry-run mode
+
+In some cases, you would like to check which files would be downloaded before actually downloading them. You can check this using the `--dry-run` parameter. It lists all files to download on the repo and checks whether they are already downloaded or not. This gives an idea of how many files have to be downloaded and their sizes.
+
+```sh
+>>> hf download openai-community/gpt2 --dry-run
+[dry-run] Fetching 26 files: 100%|█████████████| 26/26 [00:04<00:00,  6.26it/s]
+[dry-run] Will download 11 files (out of 26) totalling 5.6G.
+File                              Bytes to download
+--------------------------------- -----------------
+.gitattributes                    -
+64-8bits.tflite                   125.2M
+64-fp16.tflite                    248.3M
+64.tflite                         495.8M
+README.md                         -
+config.json                       -
+flax_model.msgpack                497.8M
+generation_config.json            -
+merges.txt                        -
+model.safetensors                 548.1M
+onnx/config.json                  -
+onnx/decoder_model.onnx           653.7M
+onnx/decoder_model_merged.onnx    655.2M
+onnx/decoder_with_past_model.onnx 653.7M
+onnx/generation_config.json       -
+onnx/merges.txt                   -
+onnx/special_tokens_map.json      -
+onnx/tokenizer.json               -
+onnx/tokenizer_config.json        -
+onnx/vocab.json                   -
+pytorch_model.bin                 548.1M
+rust_model.ot                     702.5M
+tf_model.h5                       497.9M
+tokenizer.json                    -
+tokenizer_config.json             -
+vocab.json                        -
+```
+
+For more details, check out the [download guide](./download.md#dry-run-mode).
+
 ### Specify cache directory
 
 If not using `--local-dir`, all files will be downloaded by default to the cache directory defined by the `HF_HOME` [environment variable](../package_reference/environment_variables#hfhome). You can specify a custom cache using `--cache-dir`:

docs/source/en/guides/download.md

@@ -158,6 +158,89 @@ Fetching 2 files: 100%|███████████████████
 
 For more details about the CLI download command, please refer to the [CLI guide](./cli#hf-download).
 
+## Dry-run mode
+
+In some cases, you would like to check which files would be downloaded before actually downloading them. You can check this using the `--dry-run` parameter. It lists all files to download on the repo and checks whether they are already downloaded or not. This gives an idea of how many files have to be downloaded and their sizes.
+
+Here is an example, checking on a single file:
+
+```sh
+>>> hf download openai-community/gpt2 onnx/decoder_model_merged.onnx --dry-run
+[dry-run] Will download 1 files (out of 1) totalling 655.2M
+File                           Bytes to download
+------------------------------ -----------------
+onnx/decoder_model_merged.onnx 655.2M
+```
+
+And if the file is already cached:
+
+```sh
+>>> hf download openai-community/gpt2 onnx/decoder_model_merged.onnx --dry-run
+[dry-run] Will download 0 files (out of 1) totalling 0.0.
+File                           Bytes to download
+------------------------------ -----------------
+onnx/decoder_model_merged.onnx -
+```
+
+You can also execute a dry-run on an entire repository:
+
+```sh
+>>> hf download openai-community/gpt2 --dry-run
+[dry-run] Fetching 26 files: 100%|█████████████| 26/26 [00:04<00:00,  6.26it/s]
+[dry-run] Will download 11 files (out of 26) totalling 5.6G.
+File                              Bytes to download
+--------------------------------- -----------------
+.gitattributes                    -
+64-8bits.tflite                   125.2M
+64-fp16.tflite                    248.3M
+64.tflite                         495.8M
+README.md                         -
+config.json                       -
+flax_model.msgpack                497.8M
+generation_config.json            -
+merges.txt                        -
+model.safetensors                 548.1M
+onnx/config.json                  -
+onnx/decoder_model.onnx           653.7M
+onnx/decoder_model_merged.onnx    655.2M
+onnx/decoder_with_past_model.onnx 653.7M
+onnx/generation_config.json       -
+onnx/merges.txt                   -
+onnx/special_tokens_map.json      -
+onnx/tokenizer.json               -
+onnx/tokenizer_config.json        -
+onnx/vocab.json                   -
+pytorch_model.bin                 548.1M
+rust_model.ot                     702.5M
+tf_model.h5                       497.9M
+tokenizer.json                    -
+tokenizer_config.json             -
+vocab.json                        -
+```
+
+And with files filtering:
+
+```sh
+>>> hf download openai-community/gpt2 --include "*.json"  --dry-run
+[dry-run] Fetching 11 files: 100%|█████████████| 11/11 [00:00<00:00, 80518.92it/s]
+[dry-run] Will download 0 files (out of 11) totalling 0.0.
+File                         Bytes to download
+---------------------------- -----------------
+config.json                  -
+generation_config.json       -
+onnx/config.json             -
+onnx/generation_config.json  -
+onnx/special_tokens_map.json -
+onnx/tokenizer.json          -
+onnx/tokenizer_config.json   -
+onnx/vocab.json              -
+tokenizer.json               -
+tokenizer_config.json        -
+vocab.json                   -
+```
+
+Finally, you can also make a dry-run programmatically by passing `dry_run=True` to [`hf_hub_download`] and [`snapshot_download`]. It will return a [`DryRunFileInfo`] (respectively a list of [`DryRunFileInfo`]) with for each file, their commit hash, file name and file size, whether the file is cached and whether the file would be downloaded. In practice, the file will be downloaded if not cached or if `force_download=True` is passed.
+
 ## Faster downloads
 
 There are two options to speed up downloads. Both involve installing a Python package written in Rust.

docs/source/en/package_reference/hf_api.md

@@ -45,6 +45,10 @@ models = hf_api.list_models()
 
 [[autodoc]] huggingface_hub.hf_api.DatasetInfo
 
+### DryRunFileInfo
+
+[[autodoc]] huggingface_hub.hf_api.DryRunFileInfo
+
 ### GitRefInfo
 
 [[autodoc]] huggingface_hub.hf_api.GitRefInfo

src/huggingface_hub/__init__.py

@@ -138,6 +138,7 @@
         "push_to_hub_fastai",
     ],
     "file_download": [
+        "DryRunFileInfo",
         "HfFileMetadata",
         "_CACHED_NO_EXIST",
         "get_hf_file_metadata",
@@ -625,6 +626,7 @@
     "DocumentQuestionAnsweringInputData",
     "DocumentQuestionAnsweringOutputElement",
     "DocumentQuestionAnsweringParameters",
+    "DryRunFileInfo",
     "EvalResult",
     "FLAX_WEIGHTS_NAME",
     "FeatureExtractionInput",
@@ -1147,6 +1149,7 @@ def __dir__():
     )
     from .file_download import (
         _CACHED_NO_EXIST,  # noqa: F401
+        DryRunFileInfo,  # noqa: F401
         HfFileMetadata,  # noqa: F401
         get_hf_file_metadata,  # noqa: F401
         hf_hub_download,  # noqa: F401

src/huggingface_hub/_snapshot_download.py

@@ -1,20 +1,21 @@
 import os
 from pathlib import Path
-from typing import Iterable, Optional, Union
+from typing import Iterable, List, Literal, Optional, Union, overload
 
 import httpx
 from tqdm.auto import tqdm as base_tqdm
 from tqdm.contrib.concurrent import thread_map
 
 from . import constants
 from .errors import (
+    DryRunError,
     GatedRepoError,
     HfHubHTTPError,
     LocalEntryNotFoundError,
     RepositoryNotFoundError,
     RevisionNotFoundError,
 )
-from .file_download import REGEX_COMMIT_HASH, hf_hub_download, repo_folder_name
+from .file_download import REGEX_COMMIT_HASH, DryRunFileInfo, hf_hub_download, repo_folder_name
 from .hf_api import DatasetInfo, HfApi, ModelInfo, RepoFile, SpaceInfo
 from .utils import OfflineModeIsEnabled, filter_repo_objects, logging, validate_hf_hub_args
 from .utils import tqdm as hf_tqdm
@@ -25,6 +26,81 @@
 VERY_LARGE_REPO_THRESHOLD = 50000  # After this limit, we don't consider `repo_info.siblings` to be reliable enough
 
 
+@overload
+def snapshot_download(
+    repo_id: str,
+    *,
+    repo_type: Optional[str] = None,
+    revision: Optional[str] = None,
+    cache_dir: Union[str, Path, None] = None,
+    local_dir: Union[str, Path, None] = None,
+    library_name: Optional[str] = None,
+    library_version: Optional[str] = None,
+    user_agent: Optional[Union[dict, str]] = None,
+    etag_timeout: float = constants.DEFAULT_ETAG_TIMEOUT,
+    force_download: bool = False,
+    token: Optional[Union[bool, str]] = None,
+    local_files_only: bool = False,
+    allow_patterns: Optional[Union[list[str], str]] = None,
+    ignore_patterns: Optional[Union[list[str], str]] = None,
+    max_workers: int = 8,
+    tqdm_class: Optional[type[base_tqdm]] = None,
+    headers: Optional[dict[str, str]] = None,
+    endpoint: Optional[str] = None,
+    dry_run: Literal[False] = False,
+) -> str: ...
+
+
+@overload
+def snapshot_download(
+    repo_id: str,
+    *,
+    repo_type: Optional[str] = None,
+    revision: Optional[str] = None,
+    cache_dir: Union[str, Path, None] = None,
+    local_dir: Union[str, Path, None] = None,
+    library_name: Optional[str] = None,
+    library_version: Optional[str] = None,
+    user_agent: Optional[Union[dict, str]] = None,
+    etag_timeout: float = constants.DEFAULT_ETAG_TIMEOUT,
+    force_download: bool = False,
+    token: Optional[Union[bool, str]] = None,
+    local_files_only: bool = False,
+    allow_patterns: Optional[Union[list[str], str]] = None,
+    ignore_patterns: Optional[Union[list[str], str]] = None,
+    max_workers: int = 8,
+    tqdm_class: Optional[type[base_tqdm]] = None,
+    headers: Optional[dict[str, str]] = None,
+    endpoint: Optional[str] = None,
+    dry_run: Literal[True] = True,
+) -> list[DryRunFileInfo]: ...
+
+
+@overload
+def snapshot_download(
+    repo_id: str,
+    *,
+    repo_type: Optional[str] = None,
+    revision: Optional[str] = None,
+    cache_dir: Union[str, Path, None] = None,
+    local_dir: Union[str, Path, None] = None,
+    library_name: Optional[str] = None,
+    library_version: Optional[str] = None,
+    user_agent: Optional[Union[dict, str]] = None,
+    etag_timeout: float = constants.DEFAULT_ETAG_TIMEOUT,
+    force_download: bool = False,
+    token: Optional[Union[bool, str]] = None,
+    local_files_only: bool = False,
+    allow_patterns: Optional[Union[list[str], str]] = None,
+    ignore_patterns: Optional[Union[list[str], str]] = None,
+    max_workers: int = 8,
+    tqdm_class: Optional[type[base_tqdm]] = None,
+    headers: Optional[dict[str, str]] = None,
+    endpoint: Optional[str] = None,
+    dry_run: bool = False,
+) -> Union[str, list[DryRunFileInfo]]: ...
+
+
 @validate_hf_hub_args
 def snapshot_download(
     repo_id: str,
@@ -46,7 +122,8 @@ def snapshot_download(
     tqdm_class: Optional[type[base_tqdm]] = None,
     headers: Optional[dict[str, str]] = None,
     endpoint: Optional[str] = None,
-) -> str:
+    dry_run: bool = False,
+) -> Union[str, list[DryRunFileInfo]]:
     """Download repo files.
 
     Download a whole snapshot of a repo's files at the specified revision. This is useful when you want all files from
@@ -109,9 +186,14 @@ def snapshot_download(
             Note that the `tqdm_class` is not passed to each individual download.
             Defaults to the custom HF progress bar that can be disabled by setting
             `HF_HUB_DISABLE_PROGRESS_BARS` environment variable.
+        dry_run (`bool`, *optional*, defaults to `False`):
+            If `True`, perform a dry run without actually downloading the files. Returns a list of
+            [`DryRunFileInfo`] objects containing information about what would be downloaded.
 
     Returns:
-        `str`: folder path of the repo snapshot.
+        `str` or list of [`DryRunFileInfo`]:
+            - If `dry_run=False`: Local snapshot path.
+            - If `dry_run=True`: A list of [`DryRunFileInfo`] objects containing download information.
 
     Raises:
         [`~utils.RepositoryNotFoundError`]
@@ -187,6 +269,11 @@ def snapshot_download(
     #    - f the specified revision is a branch or tag, look inside "refs".
     # => if local_dir is not None, we will return the path to the local folder if it exists.
     if repo_info is None:
+        if dry_run:
+            raise DryRunError(
+                "Dry run cannot be performed as the repository cannot be accessed. Please check your internet connection or authentication token."
+            ) from api_call_error
+
         # Try to get which commit hash corresponds to the specified revision
         commit_hash = None
         if REGEX_COMMIT_HASH.match(revision):
@@ -273,6 +360,8 @@ def snapshot_download(
         tqdm_desc = f"Fetching {len(filtered_repo_files)} files"
     else:
         tqdm_desc = "Fetching ... files"
+    if dry_run:
+        tqdm_desc = "[dry-run] " + tqdm_desc
 
     commit_hash = repo_info.sha
     snapshot_folder = os.path.join(storage_folder, "snapshots", commit_hash)
@@ -288,28 +377,33 @@ def snapshot_download(
         except OSError as e:
             logger.warning(f"Ignored error while writing commit hash to {ref_path}: {e}.")
 
+    results: List[Union[str, DryRunFileInfo]] = []
+
     # we pass the commit_hash to hf_hub_download
     # so no network call happens if we already
     # have the file locally.
-    def _inner_hf_hub_download(repo_file: str):
-        return hf_hub_download(
-            repo_id,
-            filename=repo_file,
-            repo_type=repo_type,
-            revision=commit_hash,
-            endpoint=endpoint,
-            cache_dir=cache_dir,
-            local_dir=local_dir,
-            library_name=library_name,
-            library_version=library_version,
-            user_agent=user_agent,
-            etag_timeout=etag_timeout,
-            force_download=force_download,
-            token=token,
-            headers=headers,
+    def _inner_hf_hub_download(repo_file: str) -> None:
+        results.append(
+            hf_hub_download(  # type: ignore[no-matching-overload] # ty not happy, don't know why :/
+                repo_id,
+                filename=repo_file,
+                repo_type=repo_type,
+                revision=commit_hash,
+                endpoint=endpoint,
+                cache_dir=cache_dir,
+                local_dir=local_dir,
+                library_name=library_name,
+                library_version=library_version,
+                user_agent=user_agent,
+                etag_timeout=etag_timeout,
+                force_download=force_download,
+                token=token,
+                headers=headers,
+                dry_run=dry_run,
+            )
         )
 
-    if constants.HF_HUB_ENABLE_HF_TRANSFER:
+    if constants.HF_HUB_ENABLE_HF_TRANSFER and not dry_run:
         # when using hf_transfer we don't want extra parallelism
         # from the one hf_transfer provides
         for file in filtered_repo_files:
@@ -324,6 +418,10 @@ def _inner_hf_hub_download(repo_file: str):
             tqdm_class=tqdm_class or hf_tqdm,
         )
 
+    if dry_run:
+        assert all(isinstance(r, DryRunFileInfo) for r in results)
+        return results  # type: ignore
+
     if local_dir is not None:
         return str(os.path.realpath(local_dir))
     return snapshot_folder

src/huggingface_hub/_upload_large_folder.py

@@ -31,8 +31,7 @@
 from ._commit_api import CommitOperationAdd, UploadInfo, _fetch_upload_modes
 from ._local_folder import LocalUploadFileMetadata, LocalUploadFilePaths, get_local_upload_paths, read_upload_metadata
 from .constants import DEFAULT_REVISION, REPO_TYPES
-from .utils import DEFAULT_IGNORE_PATTERNS, filter_repo_objects, tqdm
-from .utils._cache_manager import _format_size
+from .utils import DEFAULT_IGNORE_PATTERNS, _format_size, filter_repo_objects, tqdm
 from .utils._runtime import is_xet_available
 from .utils.sha import sha_fileobj