by sjkingo

An API for virtualenv/pip

129 Stars 18 Forks Last release: 9 months ago (2.1.18) BSD 2-Clause "Simplified" License 187 Commits 18 Releases

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virtualenv-api - an API for virtualenv

|Build Status| |Latest version| |BSD License|

_ is a tool to create isolated Python environments. Unfortunately, it does not expose a native Python API. This package aims to provide an API in the form of a wrapper around virtualenv.

It can be used to create and delete environments and perform package management inside the environment.

Full support is provided for all supported versions of Python.

.. _virtualenv: .. |Build Status| image:: :target: .. |Latest version| image:: :target: .. |BSD License| image:: :target:


The latest stable release is available on



$ pip install virtualenv-api

Please note that the distribution is named

, yet the Python package is named

Alternatively, you may fetch the latest version from git:


$ pip install git+

.. _PyPi:


To begin managing an environment (it will be created if it does not exist):

.. code:: python

from virtualenvapi.manage import VirtualEnvironment
env = VirtualEnvironment('/path/to/environment/name')

If you have already activated a virtualenv and wish to operate on it, simply call

without the path argument:

.. code:: python

env = VirtualEnvironment()


constructor takes some optional arguments (their defaults are shown below):
  • python=None
    - specify the Python interpreter to use. Defaults to the default system interpreter (new in 2.1.3)
  • cache=None
    - existing directory to override the default pip download cache
  • readonly=False
    - prevent all operations that could potentially modify the environment (new in 2.1.7)
  • system_site_packages=False
    - include system site packages in operations on the environment (new in 2.1.14)


Once you have a

object, you can perform operations on it.
  • Check if the
    package is installed:

.. code:: python

>>> env.is_installed('mezzanine')
  • Install the latest version of the

.. code:: python

>>> env.install('mezzanine')
  • A wheel of the latest version of the
    package (new in 2.1.4):

.. code:: python

>>> env.wheel('mezzanine')
  • Install version 1.4 of the
    package (this is pip’s syntax):

.. code:: python

>>> env.install('django==1.4')
  • Upgrade the
    package to the latest version:

.. code:: python

>>> env.upgrade('django')
  • Upgrade all packages to their latest versions (new in 2.1.7):

.. code:: python

>>> env.upgrade_all()
  • Uninstall the

.. code:: python

>>> env.uninstall('mezzanine')

Packages may be specified as name only (to work on the latest version), using pip’s package syntax (e.g.

) or as a tuple of
('django', '1.4')
  • A package may be installed directly from a git repository (must end with

.. code:: python

>>> env.install('git+git://')

New in 2.1.10:

  • A package can be installed in pip's editable mode by prefixing the package name with
    (this is pip's syntax):

.. code:: python

>>> env.install('-e git+')

New in 2.1.15:

  • Packages in a pip requirements file can be installed by prefixing the requirements file path with

.. code:: python

>>> env.install('-r requirements.txt')
  • Instances of the environment provide an

.. code:: python

>>> env.installed_packages
[('django', '1.5'), ('wsgiref', '0.1.2')]
  • A list of package names is also available in the same manner:

.. code:: python

>>> env.installed_package_names
['django', 'wsgiref']
  • Search for a package on PyPI (changed in 2.1.5: this now returns a dictionary instead of list):

.. code:: python

{'virtualenv-api': 'An API for virtualenv/pip'}
>>> len('requests'))
  • The old functionality (pre 2.1.5) of
    may be used:

.. code:: python

>>> list('requests').items())
[('virtualenv-api', 'An API for virtualenv/pip')]

Verbose output from each command is available in the environment's

file, which is appended to with each operation. Any errors are logged to

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