workingenv.py 0.6.4

Tool to create isolated Python environment

Contents

• Installation

• Summary

• Changes

• Activation

• Requirements

• Regenerating Environments

• Zope

• Using workingenv Programmatically

Installation

You don’t need to install this as a Python package; you can simply download the script and run it. This avoids a chicken-and-egg problem of installing stuff into your environment so you can start setting up environments.

You can also install it with easy_install workingenv.py, install it without setuptools (it does not depend on setuptools for installation), or install from the subversion repository with easy_install workingenv.py==dev.

Summary

This tool creates an environment that is isolated from the rest of the Python installation, eliminating site-packages and any other source of modules, so that only the modules (and versions) you install into the environment will be available. This allows for isolated and controlled environments, as well as reproduceability. This is similar to virtual-python, but without the symlinks and with some additional features.

The basic usage is:

$ python workingenv.py MyNewEnvironment
$ source MyNewEnvironment/bin/activate

After sourcing bin/activate any commands (like python setup.py install, etc) will install into the new environment. A Windows activate.bat file is also generated for that environment. Scripts like bin/easy_install will be tied to the environment, and so they will automatically install into the environment even without activation.

Changes

0.6.4: Use --always-unzip with ez_setup.py, so we don’t sometimes (on Python 2.5?) get setuptools installed as an egg. Don’t put quotes around environmental variables in activate.bat. Print out installation with nesting to show what dependencies are drawn in by what libraries.

0.6.3: Don’t raise an exception when cli|gui.exe is missing. Set always_copy = True in distutils.cfg, which avoids some problems with system-wide packages. Show some indication of progress during the Setuptools installation.

0.6.2: User the system distutils.cfg as well as the workingenv-specific distutils.cfg; helpful for picking up system-wide compiler settings. Fix problem with creating command-line scripts on Windows (missing cli.exe or gui.exe).

0.6.1: Minor bugfix, plus Windows activate.bat file now changes the prompt (from Patrick O’Brien). Also, install script as just workingenv so it doesn’t conflict with the module.

0.6: Pulls in dependencies from –requirements files, irregardless of whether a currently activated environment might provide those dependencies. Includes a setup.py file. Doesn’t print out boring messages from ez_setup.py and easy_install.

0.5: Fix the self-activation of scripts.

0.4: Fix the interaction of the --site-packages option (that brings in the global site-packages/ directory) and a global installation of setuptools. If you get an error like “site.py is not a setuptools-generated site.py; please remove it” you should upgrade and regenerate your workingenv.

0.3: Support for Setuptools 0.6c5

Activation

When you “activate” the environment, python will treat that environment as though it was the only Python environment available. It does this by setting $PYTHONPATH and overriding the standard site.py.

Installations with “setup.py install” and easy_install will go into the right place. Scripts built with easy_install (not other ways) will be tied to the environment, even if the environment isn’t activated when the script is run.

Activation itself means putting lib/python2.4/ onto $PYTHONPATH. If you don’t want to use bin/activate, just do:

$ export PYTHONPATH=”WORKINGENV/lib/python2.4” $ <anything using Python>

bin/activate also updates your prompt and sets $PATH to point to the workingenv bin/. There is no other magic to it, so you can reproduce the same functionality that way if you want. (Note also that bin/activate changes your environment, which is why it must be sourced into a shell environment.)

See this post for an initial discussion. Discussion should go to [e-mail].

Requirements

Also included is the notion of a requirement set, so you can bootstrap a complete set of packages. This is a text file with easy_installable requirements, one on each line. The file can also include -r other_file and -f place_to_find_packages. Using this you can provide a very specific working set of packages for users/developers. You may also use -e before a requirement to install that requirement into src/ in development mode.

Two examples of this sense of requirements are provided, “tg-example.txt” and “tg-0.9.txt”. Note that by putting this into a separate file, adjusting the requirements in response to testing does not require changing the requirements of any particular package. This way you can give very exacting requirements, and later adjust those requirements in response to upgrades, without causing instabilities in any one package.

Regenerating Environments

Environments carry around the settings they were created with (in .workingenv/). This allows you to run workingenv.py ENVIRONMENT over again to make updates, and settings will still be preserved.

Before overwriting any files you will be asked about the changes. Also you can use --simulate to see what it would do.

Zope

workingenv.py will work with Zope 2, but you should use the –home option (which will put everything in lib/python/ instead of lib/python2.4/). The way Zope and many Zope Products are set up, they expect this kind of layout.

Using workingenv Programmatically

You can use workingenv.main() just like the script; this is probably the best/safest way to use it programmatically. Of course calling it in a subprocess will also work.