Autoswitch Python Virtualenv

zsh-autoswitch-virtualenv is a simple and quick ZSH plugin that switches python virtualenvs automatically as you move between directories.

zsh-autoswitch-virtualenv also automatically detects and activates your Pipenv projects without any setup necessary.

• How it Works
• More Details
• Installing
• Pipenv Integration
• Commands
• Customising Messages
• Options
• Security Warnings
• Running Tests

How it Works

Simply call the mkvenv command in the directory you wish to setup a virtual environment. A virtual environment specific to that folder will now activate every time you enter it.

zsh-autoswitch-virtualenv will try detect python projects and remind you to create a virtual environment if e.g. setup.py or requirements.txt is found in the current directory.

NOTE: Pipenv projects should not use 'mkvenv'. Use 'pipenv install' instead

See the Commands section below for more detail.

More Details

Moving out of the directory will automatically deactivate the virtual environment. However you can also switch to a default python virtual environment instead by setting the AUTOSWITCH_DEFAULTENV environment variable.

Internally this plugin simply works by creating a file named .venv which contains the name of the virtual environment created (which is the same name as the current directory but can be edited if needed). There is then a precommand hook that looks for a .venv file and switches to the name specified if one is found.

For the case of pipenv projects, the plugin will look for a Pipfile and activate pipenv if it detects an existing virtual environment for it.

NOTE: you may want to add .venv to your .gitignore in git projects (or equivalent file for the Version Control you are using).

Installing

autoswitch-virtualenv requires virtualenv to be installed.

Once virtualenv is installed, add one of the following lines to your .zshrc file depending on the package manager you are using:

ZPlug

zplug "MichaelAquilina/zsh-autoswitch-virtualenv"

Antigen

antigen bundle "MichaelAquilina/zsh-autoswitch-virtualenv"

Zgen

zgen load "MichaelAquilina/zsh-autoswitch-virtualenv"

oh-my-zsh

Copy this repository to $ZSH_CUSTOM/custom/plugins, where $ZSH_CUSTOM is the directory with custom plugins of oh-my-zsh (read more):

git clone "https://github.com/MichaelAquilina/zsh-autoswitch-virtualenv.git" "$ZSH_CUSTOM/plugins/autoswitch_virtualenv"

Then add this line to your .zshrc. Make sure it is before the line source $ZSH/oh-my-zsh.sh.

plugins=(autoswitch_virtualenv $plugins)

Manual Installation

Source the plugin shell script in your ~/.zshrc profile. For example

source $HOME/zsh-autoswitch-virtualenv/autoswitch_virtualenv.plugin.zsh

Pipenv Integration

This plugin will also detect and auto activate virtualenvs made with pipenv.

Commands

mkvenv

Setup a new project with virtualenv autoswitching using the mkvenv helper command.

$ cd my-python-project
$ mkvenv
Creating my-python-project virtualenv
Found a requirements.txt. Install? [y/N]:
Collecting requests (from -r requirements.txt (line 1))
  Using cached requests-2.11.1-py2.py3-none-any.whl
Installing collected packages: requests
Successfully installed requests-2.11.1

Optionally, you can specify the python binary to use for this virtual environment

$ mkvenv --python=/usr/bin/python3

It is also possible to inherit the system site packages (which can reduce duplication on the file system and download/setup time).

$ mkvenv --system-site-packages

In fact, mkvenv supports any parameters that can be passed to python -m virtualenv. A comprehensive list of options may be found in the virtualenv guide

mkvenv will create a virtual environment with the same name as the current directory, suggest installing requirements.txt if available and create the relevant .venv file for you.

Next time you switch to that folder, you'll see the following message

$ cd my-python-project
Switching virtualenv: my-python-project  [Python 3.4.3+]
$

If you have set the AUTOSWITCH_DEFAULTENV environment variable, exiting that directory will switch back to the value set.

$ cd ..
Switching virtualenv: mydefaultenv  [Python 3.4.3+]
$

Otherwise, deactivate will simply be called on the virtualenv to switch back to the global python environment.

Autoswitching is smart enough to detect that you have traversed to a project subdirectory. So your virtualenv will not be deactivated if you enter a subdirectory.

$ cd my-python-project
Switching virtualenv: my-python-project  [Python 3.4.3+]
$ cd src
$ # Notice how this has not deactivated the project virtualenv
$ cd ../..
Switching virtualenv: mydefaultenv  [Python 3.4.3+]
$ # exited the project parent folder, so the virtualenv is now deactivated

rmvenv

You can remove the virtual environment for a directory you are currently in using the rmvenv helper function:

$ cd my-python-project
$ rmvenv
Switching virtualenv: mydefaultenv  [Python 2.7.12]
Removing myproject...

This will delete the virtual environment in .venv and remove the .venv file itself. The rmvenv command will fail if there is no .venv file in the current directory:

$ cd my-non-python-project
$ rmvenv
No .venv file in the current directory!

disable_autoswitch_virtualenv

Temporarily disables autoswitching of virtualenvs when moving between directories.

enable_autoswitch_virtualenv

Re-enable autoswitching of virtualenvs (if it was previously disabled).

Customising Messages

By default, the following message is displayed in bold when an alias is found:

Switching %venv_type: %venv_name [%py_version]

Where the following variables represent:

• %venv_type - the type of virtualenv being activated (virtualenv, pipenv)
• %venv_name - the name of the virtualenv being activated
• %py_version - the version of python used by the virtualenv being activated

This default message can be customised by setting the AUTOSWITCH_MESSAGE_FORMAT environment variable.

If for example, you wish to display your own custom message in red, you can add the following to your ~/.zshrc:

export AUTOSWITCH_MESSAGE_FORMAT="$(tput setaf 1)Switching to %venv_name 🐍 %py_version $(tput sgr0)"

$(tput setaf 1) generates the escape code terminals use for red foreground text. $(tput sgr0) sets the text back to a normal color.

You can read more about how you can use tput and terminal escape codes here: http://wiki.bash-hackers.org/scripting/terminalcodes

Options

The following options can be configured by setting the appropriate variables within your ~/.zshrc file.

Setting a default virtual environment

You can set a default virtual environment to switch to when not in a python project by setting the value of AUTOSWITCH_DEFAULTENV to the name of a virtualenv. For example:

export AUTOSWITCH_DEFAULTENV="mydefaultenv"

Setting a default python binary

You may specify a default python binary to use when creating virtualenvs by setting the value of AUTOSWITCH_DEFAULT_PYTHON. For example:

export AUTOSWITCH_DEFAULT_PYTHON="/usr/bin/python3"

You may still override this default as usual by passing the --python parameter to the mkvenv command.

Autoswitch file name

By default, the .venv file is searched for in each directory in order to tell if a virtualenv should be automatically activated.

If this needs to be changed (e.g. it conflicts with something else) then it may be changed by setting the value of AUTOSWITCH_FILE. For example:

export AUTOSWITCH_FILE=".autoswitch"

Default requirements file

You may specify a default requirements file to use when creating a virtualenv by setting the value of AUTOSWTICH_DEFAULT_REQUIREMENTS. For example:

export AUTOSWITCH_DEFAULT_REQUIREMENTS="$HOME/.requirements.txt"

If the value is set and the target file exists you will be prompted to install with that file each time you create a new virtualenv.

Set verbosity when changing environments

You can prevent verbose messages from being displayed when moving between directories. You can do this by setting AUTOSWITCH_SILENT to a non-empty value.

Choosing where virtualenvs are stored

By default, virtualenvs created are placed in $HOME/.virtualenvs - which is the same location that the virtualenvwrapper package uses.

If you wish to change this to another location, simply set the value of the environment variable AUTOSWITCH_VIRTUAL_ENV_DIR.

If you wish for virtual environments to be stored within each project directory then you can set the variable to use a relative path. For example:

export AUTOSWITCH_VIRTUAL_ENV_DIR=".virtualenv"

Customising pip install invocation

By default mkvenv will install setup.py via pip in editable (i.e. development) mode. See here and here for further information. To change this set AUTOSWITCH_PIPINSTALL to FULL.

Security Warnings

zsh-autoswitch-virtualenv will warn you and refuse to activate a virtual envionrment automatically in the following situations:

• You are not the owner of the .venv file found in a directory.
• The .venv file has weak permissions. I.e. it is writable by other users on the system.

In both cases, the warnings should explain how to fix the problem.

These are security measures that prevents other, potentially malicious users, from switching you to a virtual environment you did not want to switch to.

Running Tests

Install zunit. Run zunit in the root directory of the repo.

$ zunit
Launching ZUnit
ZUnit: 0.8.2
ZSH:   zsh 5.3.1 (x86_64-suse-linux-gnu)

✔ _check_venv_path - returns nothing if not found
✔ _check_venv_path - finds .venv in parent directories
✔ _check_venv_path - returns nothing with root path
✔ check_venv - Security warning for weak permissions

NOTE: It is required that you use a minimum zunit version of 0.8.2