python - Installing python3 in a python2 virtual environment

Question

I have a Flask application that is running in a Python 2 virtual environment.

I'm looking to run a Python 3 program, so I need to install python3 into the virtual environment. How do I do this? Do I have to recreate the environment? Is this a difficult migration?

Answer 1

It's not recommended to mix multiple versions of Python. In fact, I don't think it's even possible.

Creating a new virtualenv isn't difficult at all:

1. Get the list of modules in the current virtualenv

   source /path/to/current/bin/activate
   pip freeze > /tmp/requirements.txt
   

2. Create a new virtualenv. Either change into a suitable directory before executing the virtualenv command or give a full path.

   deactivate
   virtualenv -p python3 envname
   

3. Install modules

   source envname/bin/activate
   pip install -r /tmp/requirements.txt
   

That's it.