requirements.txt vs Pipfile in heroku flask webapp deployment?

Question

I'm trying to deploy a Flask webapp to Heroku and I have seen conflicting information as to which files I need to include in the git repository.

My webapp is built within a virtual environment (venv), so I have a Pipfile and a Pipfile.lock. Do I also need a requirements.txt? Will one supersede the other?

Another related question I have is what would occur if a certain package failed to install in the virtual environment: can I manually add it to the requirements.txt or Pipfile? Would this effectively do the same thing as pipenv install ... or is that doing something else beyond adding the package to the list of requirements (considering Heroku is installing the packages upon deployment).

Answer 1

You do not need requirements.txt.

The Pipfile and Pipfile.lock that Pipenv uses are designed to replace requirements.txt. If you include all three files, Heroku will ignore the requirements.txt and just use Pipenv.

If you have build issues with a particular library locally I urge you to dig into that and get everything working on your local machine. But this isn't technically required... as long as the Pipfile and Pipfile.lock contain the right information (including hashes), Heroku will try to install your dependencies.