download a file, retry if intterupted

file_download.py

@@ -0,0 +1,59 @@
+from _io import BufferedWriter
+from argparse import ArgumentParser
+from datetime import datetime, timedelta
+from pathlib import Path
+from shutil import copyfileobj
+from time import sleep
+from zipfile import ZipFile
+import logging
+import requests
+
+
+def file_download(*, url: str, file_open: BufferedWriter) -> None:
+    response = requests.head(url)
+    content_length = response.headers["content-length"]
+    file_end = file_open.tell()
+    headers = {"range": f"bytes={file_end}-{content_length}"}
+    logging.info(headers)
+
+    try:
+        with requests.get(url, headers=headers, stream=True) as response:
+            copyfileobj(response.raw, file_open)
+    except Exception as error:
+        logging.error(error)
+        sleep(1)
+        file_download(url=url, file_open=file_open)
+
+
+def zipfile_download():
+    description = """
+    Download large zipfile from URL, retry at offset if interrupted, check zip.
+    """
+    parser = ArgumentParser(description=description)
+    parser.add_argument("-v", "--verbose", action="count")
+    parser.add_argument("-url", "--url", required=True, help="URL to zipfile")
+    parser.add_argument("-o", "--path", required=True, help="path to write zipfile")
+    args = parser.parse_args()
+    level = logging.DEBUG if args.verbose else logging.INFO
+    logging.basicConfig(level=level)
+    logging.info(args)
+    today = datetime.utcnow().strftime("%Y%m%d")
+    logging.info(today)
+
+    path = Path(args.path)
+
+    if path.exists():
+        logging.info(f'output path exists, resuming: "{path}"')
+
+    with path.open("wb") as file_open:
+        file_download(url=args.url, file_open=file_open)
+
+    with ZipFile(path) as zip_file:
+        file_list = zip_file.namelist()
+
+    if not file_list:
+        raise Exception(f'zipfile_empty "{args.url}"')
+
+
+if __name__ == "__main__":
+    zipfile_download()