Managing Python using pyenv, virtualenv, and pyenv-virtualenv

installing_python.md

Managing Python using pyenv, virtualenv, and pyenv-virtualenv

Problem: You want to maintain multiple different versions of python and keep packages separated based on projects that you're working on.

Solution: Use the pyenv, virtualenv tools along with the pyenv-virutalenv plugin to manage multiple versions of python and seamlessly integrate them with your projects' virtual environments.

Installation

All of these steps are specific for Mac OS X. For other operating systems, I've provided links to each tool's documentation.

You'll be installing the following things:

• pyenv + any number of python versions you want
• virtualenv
• pyenv-virtualenv

virtualenv

Docs

1. Install globally with pip (if you have pip 1.3 or greater installed globally):

   sh $ [sudo] pip install virtualenv

pyenv

Docs

1. Install pyenv using the Homebrew package manager for Mac OS X.

   $ brew update
   $ brew install pyenv

   To upgrade pyenv in the future, use upgrade instead of install.

2. Add pyenv init to your shell to enable shims and autocompletion. Please make sure eval "$(pyenv init -)" is placed toward the end of the shell configuration file since it manipulates PATH during the initialization.

   $ echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n  eval "$(pyenv init -)"\nfi' >> ~/.bash_profile

   Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile.

   Ubuntu and Fedora note: Modify your ~/.bashrc file instead of ~/.bash_profile.

   General warning: There are some systems where the BASH_ENV variable is configured to point to .bashrc. On such systems you should almost certainly put the abovementioned line eval "$(pyenv init -)" into .bash_profile, and not into .bashrc. Otherwise you may observe strange behaviour, such as pyenv getting into an infinite loop. See #264 for details.

3. Restart your shell so the path changes take effect. You can now begin using pyenv.

   $ exec "$SHELL"

4. Install Python versions into $(pyenv root)/versions.

   For example, to download and install Python 2.7.8, run:

   $ pyenv install 2.7.8

   NOTE: If you need to pass configure option to build, please use CONFIGURE_OPTS environment variable.

   NOTE: If you want to use proxy to download, please use http_proxy and https_proxy environment variable.

   NOTE: If you need to use Pyinstaller, you will need to install your Python versions with framework support enabled, like so:

   $ env PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install 3.5.0

   NOTE: If you are having trouble installing a python version, please visit the wiki page about Common Build Problems or the FAQs section

pyenv-virtualenv

Docs

1. Install pyenv-virtualenv using the Homebrew package manager for Mac OS X.

   $ brew update
   $ brew install pyenv-virtualenv

   To upgrade pyenv-virtualenv in the future, use upgrade instead of install.

2. Add pyenv virtualenv-init to your shell to enable auto-activation of virtualenvs. This is enirely optional but pretty useful.

   sh $ echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.bash_profile

   Fish shell note: Add this to your ~/.config/fish/config.fish

   sh status --is-interactive; and source (pyenv virtualenv-init -|psub)

   Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile.

   Pyenv note: You may also need to add eval "$(pyenv init -)" to your profile if you haven't done so already.

3. Restart your shell to enable pyenv-virutalenv

   sh $ exec "$SHELL"

Usage

Create project based virtualenv and automatically activate/deactivate

1. Make sure the version of python you'll be using is installed

   For example, to download and install Python 3.6.3, run:

   $ pyenv install 3.6.3

2. Create virtualenv based on your required version of python

   Provide the name and version of python to use. If the version is left blank, it will use your environment's current version. You can check your current version using $ pyenv versions.

   sh $ pyenv virtualenv 3.6.3 venv36

   NOTE: You can list existing virtualenvs with pyenv virtualenvs

   NOTE: You can delete existing virtualenvs with pyenv uninstall <virtualenv_name>

3. Set your project to always use this virtualenv.

   sh $ pyenv local venv36

   This will create a local file called .python-version. If you've set everything up correctly, this virtualenv should be activated upon entering this directory and deactivated when leaving.

This:

export PATH="$HOME/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

in ~/.zshrc works!