I'm also python dev and I'm embracing docker for delivering my app to users.

> Why is docker better than virtualenv with a requirements.txt file

One of issues that `docker-compose build` solves better is that venv is superconfusing to your non-python users. I've had people:

- skip it and do `python setup.py install` instead - skip it and install requirements globally `pip install -r requirements.txt` because thats how it worked for them last time they used python - version control their `venv` directory - backup and upload their `venv` directory on new server when moving

Now they just do `./appctl setup` that asks them for few things, writes `setup.env` file for docker-compose, and then runs `docker-compose build`

But this is only beginning. Thanks to `docker-compose` that `build` step also installs:

- PostgreSQL database - Redis for caching and message queue - UWSGI - Celery - Nginx proxy