Add machine readable download progress option

news/11508.feature.rst

@@ -0,0 +1 @@
+Add a new progress_bar type that allows machine-readable (json) download progress

src/pip/_internal/cli/cmdoptions.py

@@ -226,9 +226,12 @@ class PipOption(Option):
     "--progress-bar",
     dest="progress_bar",
     type="choice",
-    choices=["on", "off"],
+    choices=["on", "off", "json"],
     default="on",
-    help="Specify whether the progress bar should be used [on, off] (default: on)",
+    help=(
+        "Specify whether the progress bar should be used"
+        " [on, off, json] (default: on)"
+    ),
 )
 
 log: Callable[..., Option] = partial(

src/pip/_internal/cli/progress_bars.py

@@ -1,4 +1,5 @@
 import functools
+from json import dumps
 from typing import Callable, Generator, Iterable, Iterator, Optional, Tuple
 
 from pip._vendor.rich.progress import (
@@ -55,14 +56,43 @@ def _rich_progress_bar(
             progress.update(task_id, advance=len(chunk))
 
 
+class _MachineReadableProgress:
+    def __init__(
+        self, iterable: Iterable[bytes], size: int, filename: Optional[str] = None
+    ) -> None:
+        self._iterable = iter(iterable)
+        self._size = size
+        self._progress = 0
+        self._filename = filename
+
+    def __iter__(self) -> Iterator[bytes]:
+        return self
+
+    def __next__(self) -> bytes:
+        chunk = next(self._iterable)
+        self._progress += len(chunk)
+        progress_info = {
+            "file": self._filename,
+            "current": self._progress,
+            "total": self._size,
+        }
+        print(
+            f"PROGRESS:{dumps(progress_info)}",
+            flush=True,
+        )
+        return chunk
+
+
 def get_download_progress_renderer(
-    *, bar_type: str, size: Optional[int] = None
+    *, bar_type: str, size: Optional[int] = None, filename: Optional[str] = None
 ) -> DownloadProgressRenderer:
     """Get an object that can be used to render the download progress.
 
     Returns a callable, that takes an iterable to "wrap".
     """
     if bar_type == "on":
         return functools.partial(_rich_progress_bar, bar_type=bar_type, size=size)
+    elif bar_type == "json":
+        return functools.partial(_MachineReadableProgress, size=size, filename=filename)
     else:
         return iter  # no-op, when passed an iterator

src/pip/_internal/network/download.py

@@ -65,7 +65,9 @@ def _prepare_download(
     if not show_progress:
         return chunks
 
-    renderer = get_download_progress_renderer(bar_type=progress_bar, size=total_length)
+    renderer = get_download_progress_renderer(
+        bar_type=progress_bar, size=total_length, filename=link.filename
+    )
     return renderer(chunks)