Add `--pipfile Pipfile.lock` as an alternative of `-r requirements.txt`

[olibre]

What's the problem this feature will solve?

I use container to deploy Python application to production. The container building script performs the following command lines:

python3 -m pip install pipenv
python3 -m pipenv sync  # Install modules from Pipenv.lock 
python3 -m pipenv run python3 -m pip freeze > requirements.txt
python3 -m pip install -r requirements.txt
python3 -m pip uninstall pipenv
rm requirements.txt

Describe the solution you'd like

Replace the above command lines by just one pretty pip option:

python3 -m pip install --pipfile Pipfile.lock

Additional context

The project https://github.com/pypa/pipfile/blob/master/README.rst states:

Pipfile and its sister Pipfile.lock are a replacement for the existing standard pip's requirements.txt file.

Let's start the movement by adding an experimental option in next pip release 😄

EDIT: My colleague has just pointed me that this has already been (eventually) planed. The same document, at chapter Pip Integration (eventual) says:

pip will grow a new command line option, -p / --pipfile to install the versions as specified in a Pipfile, similar to its existing -r / --requirement argument for installing requirements.txt files.

[pfmoore]

I'm not sure there's consensus that pipenv.lock is a replacement for requirements.txt (regardless of what is stated in that project's repository) and I'm cautious about adding an option to pip that is specific to another project (will we then get requests to add an option for Poetry's lock file format?)

At a minimum, I'd like to see some discussion within the community that resulted in agreement that pipenv.lock was a standard format, before adding this (and in particular, I'd like the poetry devs to have bought into that agreement).

[pradyunsg]

There's discussion about a standard lock file format: https://discuss.python.org/t/structured-exchangeable-lock-file-format-requirements-txt-2-0/876

[pradyunsg]

Poetry's author hasn't really interacted much AFAICT -- @sdispater are you interested in helping figure out how to improve existing tooling?

[ncoghlan]

Also see pypa/pipfile#108 for discussion of some of the potential design details to be considered.

In the meantime, note that 'pipenv lock' includes native support for generating a requirements.txt file, so it isn't necessary to use pip freeze for that: https://docs.pipenv.org/en/latest/advanced/#generating-a-requirements-txt