add custom user agent for download_url (#3498)

* add custom user agent for download_url

* fix progress bar

* lint

* [test] use repo instead of nightly for download tests

.github/workflows/tests-schedule.yml

@@ -26,10 +26,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
-      - name: Install PyTorch from the nightlies
-        run: |
-          pip install numpy
-          pip install --pre torch torchvision -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html
+      - name: Install torch nightly build
+        run: pip install --pre torch -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html
+
+      - name: Install torchvision
+        run: pip install -e .
 
       - name: Install all optional dataset requirements
         run: pip install scipy pandas pycocotools lmdb requests

test/test_datasets_download.py

@@ -14,7 +14,7 @@ import warnings
 import pytest
 
 from torchvision import datasets
-from torchvision.datasets.utils import download_url, check_integrity, download_file_from_google_drive
+from torchvision.datasets.utils import download_url, check_integrity, download_file_from_google_drive, USER_AGENT
 
 from common_utils import get_tmp_dir
 from fakedata_generation import places365_root
@@ -150,7 +150,7 @@ def assert_server_response_ok():
 
 
 def assert_url_is_accessible(url, timeout=5.0):
-    request = Request(url, headers=dict(method="HEAD"))
+    request = Request(url, headers={"method": "HEAD", "User-Agent": USER_AGENT})
     with assert_server_response_ok():
         urlopen(request, timeout=timeout)
 
@@ -160,7 +160,8 @@ def assert_file_downloads_correctly(url, md5, timeout=5.0):
         file = path.join(root, path.basename(url))
         with assert_server_response_ok():
             with open(file, "wb") as fh:
-                response = urlopen(url, timeout=timeout)
+                request = Request(url, headers={"User-Agent": USER_AGENT})
+                response = urlopen(request, timeout=timeout)
                 fh.write(response.read())
 
         assert check_integrity(file, md5=md5), "The MD5 checksums mismatch"

torchvision/datasets/utils.py

@@ -7,11 +7,28 @@ import tarfile
 from typing import Any, Callable, List, Iterable, Optional, TypeVar
 from urllib.parse import urlparse
 import zipfile
+import urllib
+import urllib.request
+import urllib.error
 
 import torch
 from torch.utils.model_zoo import tqdm
 
 
+USER_AGENT = "pytorch/vision"
+
+
+def _urlretrieve(url: str, filename: str, chunk_size: int = 1024) -> None:
+    with open(filename, "wb") as fh:
+        with urllib.request.urlopen(urllib.request.Request(url, headers={"User-Agent": USER_AGENT})) as response:
+            with tqdm(total=response.length) as pbar:
+                for chunk in iter(lambda: response.read(chunk_size), ""):
+                    if not chunk:
+                        break
+                    pbar.update(chunk_size)
+                    fh.write(chunk)
+
+
 def gen_bar_updater() -> Callable[[int, int, int], None]:
     pbar = tqdm(total=None)
 
@@ -83,8 +100,6 @@ def download_url(
         md5 (str, optional): MD5 checksum of the download. If None, do not check
         max_redirect_hops (int, optional): Maximum number of redirect hops allowed
     """
-    import urllib
-
     root = os.path.expanduser(root)
     if not filename:
         filename = os.path.basename(url)
@@ -108,19 +123,13 @@ def download_url(
     # download the file
     try:
         print('Downloading ' + url + ' to ' + fpath)
-        urllib.request.urlretrieve(
-            url, fpath,
-            reporthook=gen_bar_updater()
-        )
+        _urlretrieve(url, fpath)
     except (urllib.error.URLError, IOError) as e:  # type: ignore[attr-defined]
         if url[:5] == 'https':
             url = url.replace('https:', 'http:')
             print('Failed download. Trying https -> http instead.'
                   ' Downloading ' + url + ' to ' + fpath)
-            urllib.request.urlretrieve(
-                url, fpath,
-                reporthook=gen_bar_updater()
-            )
+            _urlretrieve(url, fpath)
         else:
             raise e
     # check integrity of downloaded file