Managing Application Dependencies - Python Packaging User Guide (original) (raw)

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The package installation tutorialcovered the basics of getting set up to install and update Python packages.

However, running these commands interactively can get tedious even for your own personal projects, and things get even more difficult when trying to set up development environments automatically for projects with multiple contributors.

This tutorial walks you through the use of Pipenv to manage dependencies for an application. It will show you how to install and use the necessary tools and make strong recommendations on best practices.

Keep in mind that Python is used for a great many different purposes, and precisely how you want to manage your dependencies may change based on how you decide to publish your software. The guidance presented here is most directly applicable to the development and deployment of network services (including web applications), but is also very well suited to managing development and testing environments for any kind of project.

For alternatives, see Other Tools for Application Dependency Management.

Installing Pipenv

Pipenv is a dependency manager for Python projects. If you’re familiar with Node.js’ npm or Ruby’s bundler, it is similar in spirit to those tools. While pip alone is often sufficient for personal use, Pipenv is recommended for collaborative projects as it’s a higher-level tool that simplifies dependency management for common use cases.

Use pip to install Pipenv:

Unix/macOS

python3 -m pip install --user pipenv

Windows

py -m pip install --user pipenv

Installing packages for your project

Pipenv manages dependencies on a per-project basis. To install packages, change into your project’s directory (or just an empty directory for this tutorial) and run:

cd myproject pipenv install requests

Pipenv will install the Requests library and create a Pipfilefor you in your project’s directory. The Pipfile is used to track which dependencies your project needs in case you need to re-install them, such as when you share your project with others. You should get output similar to this (although the exact paths shown will vary):

Creating a Pipfile for this project... Creating a virtualenv for this project... Using base prefix '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6' New python executable in ~/.local/share/virtualenvs/tmp-agwWamBd/bin/python3.6 Also creating executable in ~/.local/share/virtualenvs/tmp-agwWamBd/bin/python Installing setuptools, pip, wheel...done.

Virtualenv location: ~/.local/share/virtualenvs/tmp-agwWamBd Installing requests... Collecting requests Using cached requests-2.18.4-py2.py3-none-any.whl Collecting idna<2.7,>=2.5 (from requests) Using cached idna-2.6-py2.py3-none-any.whl Collecting urllib3<1.23,>=1.21.1 (from requests) Using cached urllib3-1.22-py2.py3-none-any.whl Collecting chardet<3.1.0,>=3.0.2 (from requests) Using cached chardet-3.0.4-py2.py3-none-any.whl Collecting certifi>=2017.4.17 (from requests) Using cached certifi-2017.7.27.1-py2.py3-none-any.whl Installing collected packages: idna, urllib3, chardet, certifi, requests Successfully installed certifi-2017.7.27.1 chardet-3.0.4 idna-2.6 requests-2.18.4 urllib3-1.22

Adding requests to Pipfile's [packages]...

Using installed packages

Now that Requests is installed you can create a simple main.py file to use it:

import requests

response = requests.get('https://httpbin.org/ip')

print('Your IP is {0}'.format(response.json()['origin']))

Then you can run this script using pipenv run:

pipenv run python main.py

You should get output similar to this:

Using pipenv run ensures that your installed packages are available to your script. It’s also possible to spawn a new shell that ensures all commands have access to your installed packages with pipenv shell.

Next steps

Congratulations, you now know how to effectively manage dependencies and development environments on a collaborative Python project! ✨ 🍰 ✨

If you’re interested in creating and distributing your own Python packages, see the tutorial on packaging and distributing packages.

Note that when your application includes definitions of Python source packages, they (and their dependencies) can be added to your pipenv environment withpipenv install -e <relative-path-to-source-directory> (e.g.pipenv install -e . or pipenv install -e src).

Other Tools for Application Dependency Management

If you find this particular approach to managing application dependencies isn’t working well for you or your use case, you may want to explore these other tools and techniques, listed in alphabetical order, to see if one of them is a better fit: