Get virtualenv working inside Docker for zappa requirement

[mateoclarke]

Oh no! An error occurred! :(

==============

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/zappa/cli.py", line 2712, in handle
    sys.exit(cli.handle())
  File "/usr/local/lib/python2.7/dist-packages/zappa/cli.py", line 480, in handle
    self.init()
  File "/usr/local/lib/python2.7/dist-packages/zappa/cli.py", line 1547, in init
    self.check_venv()
  File "/usr/local/lib/python2.7/dist-packages/zappa/cli.py", line 2649, in check_venv
    "Learn more about virtual environments here: " + click.style("http://docs.python-guide.org/en/latest/dev/virtualenvs/", bold=False, fg="cyan"))
ClickException: Zappa requires an active virtual environment!
Learn more about virtual environments here: http://docs.python-guide.org/en/latest/dev/virtualenvs/

==============

We could try to setup virtualenv inside our existing Dockerfile, but so far, this is not working.

Here are some alternatives using a different base image:

• https://blog.zappa.io/posts/docker-zappa-and-python3
• https://edgarroman.github.io/zappa-django-guide/setup/#approach-2-docker-with-zappa-recommended

[tom-montgomery]

Reverted to pre-zappa/flask