Rebuilding_a_Virtualenv.md

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Rebuilding a Virtualenv - Link to Original

If you need to rebuild your virtualenv following a system image upgrade

The instructions below will contain instructions for people who use plain virtualenv and virtualenvwrapper; make sure that you use the appropriate ones for the kind of virtualenv you're using. Use a Bash console to enter the commands.

1) Use a requirements.txt file to record what packages you're using

If you've already got a requirements.txt file, you can skip this bit, although you may want to just do the bit where we double-check what version of Python we're using.

1. Activate your virtualenv, using source /home/myusername/path/to/virtualenv/bin/activate or, if you're using virtualenvwrapper workon my-virtualenv-name
2. Save the list of packages to a requirements file
   • pip freeze > /tmp/requirements.txt
3. Double-check which version of python is in your virtualenv
   • python --version
4. Deactivate the virtualenv
   • deactivate

2) Remove your old virtualenv

Using plain virtualenvs:

rm -rf /home/myusername/path/to/virtualenv

or, if using virtualenvwrapper:

rmvirtualenv my-virtualenv-name

3) Create a new virtualenv

Using the appropriate Python version in place of X.Y:

virtualenv --python\=pythonX.Y /home/myusername/path/to/virtualenv

or, with virtualenvwrappper

mkvirtualenv --python\=pythonX.Y my-virtualenv-name

4) Reinstall your packages

pip install -r /tmp/requirements.txt  \# or path to your existing requirements.txt

5) Restart your web app.

On the Web tab, use the "Reload" button to restart your website code using the new virtualenvs -- don't forget to do this for all of your websites if you have several.

You will also need to restart any always-on tasks that use them -- just disable them, then enable them again. Scheduled tasks that use virtualenvs will pick them up the next time they run.

6) All done!