Getting Started with Pipenv

If you’re a Python developer, you probably know about pip and the different environment management solutions like virtualenv or venv. The pip tool is currently the standard way to install a Python package. Virtualenv has been a popular way of isolating Python environments for a long time. Pipenv combines the very best of these tools and brings us the one true way to install packages while keeping the dependencies from each project isolated. It claims to have brought the very best from all other packaging worlds (the package manager for other languages / runtimes / frameworks) to the Python world. From what I have seen so far, that claim is quite valid. And it does support Windows pretty well too.

How does Pipenv work?

Pipenv works by creating and managing a virtualenv and a Pipfile for your project. When we install / remove Python packages, the changes are reflected in the Pipfile. It also generates a lock file named Pipfile.lock which is used to lock the version of dependencies and help us produce deterministic builds when needed. In a typical virtualenv setup, we usually create and manage the virtualenv ourselves. Then we activate the environment and pip just installs / uninstalls from that particular virtual environment. Packages like virtualenvwrapper helps us easily create and activate virtualenv with some of it’s handy features. But pipenv takes things further by automating a large part of that. The Pipfile would also make more sense if you have used other packaging systems like Composer, npm, bundler etc.

Getting Started

We need to start by installing pipenv globally. We can install it using pip from PyPi:

pip install pipenv

Now let’s switch to our project directory and try installing a package:

pipenv install flask

When you first run the pipenv install command, you will notice it creates a virtualenv, Pipfile and Pipfile.lock for you. Feel free to go ahead inspect their contents. If you’re using an IDE like PyCharm and want to configure your project interpreter, it would be a good idea to note down the virtualenv path.

Since we have installed Flask, let’s try and running a sample app. Here’s my super simple REST API built with Flask:

from flask import Flask, jsonify

app = Flask(__name__)

def hello_world():
    return jsonify({"message": "Hello World!"})

Assuming that you have the FLASK_APP environment variable set to (which contains the above code), we can just run the app like this:

pipenv run flask run

Any executables in the current environment can be run using the pipenv run command. But I know what you might be thinking – we want to do just flask run, not use the entire, long command. That’s easy too. We just need to activate the virtualenv with this command:

pipenv shell

Now you can just do flask run or in fact run any executables in the way we’re used to doing.

Handling Dependencies

We can install and uninstall packages using the install and uninstall commands. When we install a new package, it’s added to our Pipfile and the lock file is updated as well. When we uninstall a package, the Pipfile and the lock files are again updated to reflect the change. The update command uninstalls the packages and installs them again so we have the latest updates.

If you would like to check your dependency graph, just use the graph command which will print out the dependencies in a nice format, kind of like this:

PS C:\Users\Masnun\Documents\Python\pipenvtest> pipenv graph
  - billiard [required: >=,<3.6.0, installed:]
  - kombu [required: >=4.0.2,<5.0, installed: 4.1.0]
    - amqp [required: >=2.1.4,<3.0, installed: 2.2.2]
      - vine [required: >=1.1.3, installed: 1.1.4]
  - pytz [required: >dev, installed: 2017.3]
  - click [required: >=2.0, installed: 6.7]
  - itsdangerous [required: >=0.21, installed: 0.24]
  - Jinja2 [required: >=2.4, installed: 2.10]
    - MarkupSafe [required: >=0.23, installed: 1.0]
  - Werkzeug [required: >=0.7, installed: 0.12.2]

Pipenv is Awesome!

Trust me, it is! It packs a lot of cool and useful features that can help gear up your Python development workflow. There are just too many to cover in a blog post. I would recommend checking out the Pipenv Docs to get familiar with it more.

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