Show progress bar when downloading package in verbose mode

[atugushev]

Resolves #832.

Demonstration:

Changelog-friendly one-liner: Show progress bar when downloading package in a verbose mode of pip-compile.

Contributor checklist

• Provided the tests for the changes.
• Gave a clear one-line description in the PR (that the maintainers can add to CHANGELOG.md on release).
• Assign the PR to an existing or new milestone for the target version (following Semantic Versioning).

[codecov]

Codecov Report

Merging #949 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #949   +/-   ##
=======================================
  Coverage   99.44%   99.45%           
=======================================
  Files          36       36           
  Lines        2540     2554   +14     
  Branches      312      314    +2     
=======================================
+ Hits         2526     2540   +14     
  Misses          8        8           
  Partials        6        6           

Impacted Files	Coverage Δ
piptools/logging.py	100.00% <100.00%> (ø)
piptools/repositories/pypi.py	93.68% <100.00%> (+0.42%)	⬆️

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[AndydeCleyre]

It looks good! I just want to note, in case this is surprising or not desirable:

If run with stderr in foreground and stdout directed to a file, the progress bar is not shown.

[atugushev]

Thanks for review @AndydeCleyre! It seems pip prints logs to stdout, but pip-tools to stderr. Then I'll pull this out from the upcoming release and figure out later what to do.

[atugushev]

It seems pip prints logs to stdout, but pip-tools to stderr. Then I'll pull this out from the upcoming release and figure out later what to do.

I think we could fix that by patching:

1. pip's console logger stream to sys.stderr
2. pip._internal.cli.progress_bars.DownloadProgressSpinner.file = sys.stderr

I also discovered that hashing progress bar prints to stdout (addressed in #1113), could be fixed with progressbar(..., file=sys.stderr)

pip-tools/piptools/repositories/pypi.py

Line 286 in 7a52ce8

context_manager = progressbar(chunks, length=iter_length, label=" ")

[atugushev]

@AndydeCleyre

Fixed in 5cecccf6085ef11c35e6217a829652b4496a768e. Could you take a look please?

[AndydeCleyre]

LGTM 👍

And thanks for adding the logging comments, especially the difference between pip log level and pip-tools'.

[atugushev]

Byt the way, this PR would also help with investigating such issues like #1116 by pip-compile -vv

[atugushev]

Thank you so much for the feedback @AndydeCleyre!