Support for environment variables in requirement specifiers

[gioele]

Pip should accept bash-like enviroment variables in requirement specifiers and substitute them on the fly when pip is run.

What's the problem this feature will solve?

One possible use of this feature is installing packages from private GitHub repositories via OAuth. Right now this is not possible without storing the OAuth token in plain text in requirements.txt like, for example, git+https://1234abcdef56789:x-oauth-basic@github.com/myorg/private-package.git@v2.1.

Describe the solution you'd like

It would be nice if bash-like enviroment variables where accepted and substituted on the fly when pip is run. For example:

git+https://${GIT_TOKEN}:x-oauth-basic@github.com/myorg/private-package.git@v2.1

Alternative Solutions

A workaround is to use pip install -r <(envsubst < requirements.txt) instead of pip install -r requirements.txt, but this would not work when pip is invoked by other tools like pipenv.

[xavfernandez]

This should already be the case since pip 10 with #3728 ...

[gioele]

Indeed pip v10+ does support replacing env variables in requirements.txt files. Thanks for the info.