Create and activate a virtual environment

python3 -m venv path/to/venv # or `virtualenv path/to/venv`
source <path/to/venv>/bin/activate

A virtual environment will make the current system or specified version of python and pip available and allow packages to be installed non-globally. install with pip3 install virtualenv. If you want to drop the current virtual environment: deactivate. And you can switch to another env with using the commands above.

Run from the terminal

Using the flask application

app is the package loaded by flask run which __init__s the Flask app (bong) by importing module baz.py which has the magic words: bong = Flask(__name__). If the Flask target is the package app, __init__.py runs, importing baz and conditionally calling bong.run() if it is the entry point (__main__) which will start the Flask app.

# export FLASK_APP=app # if constant default is needed
# export FLASK_ENV=development # if you want debug and reload
FLASK_APP=app flask run
# python -m app.__init__ # Pretty much the python equivalent invocation

Also, you can run the baz.py module directly since it instantiates the Flask app (bong) and contains an identical conditional call to bong.run(). Wrapping bong.run() in a check to see if the module is the application entry keeps Flask from starting twice (which Flask rejects with a warning).

FLASK_APP=app.baz flask run
# python -m app.baz # equivalent invocation of module `baz.py` without starting flask first, but warns that app.baz is loaded and executed out-of order. DON'T DO THIS

Running with gunicorn

gunicorn is a WSGI compliant server, so it can run the Flask app bong we set up by invoking the package app. Other servers will work, too

gunicorn app:bong

Finally, we can start the Flask app with run.py in the root of the project. run.py imports the app package (which imports the baz module, same as FLASK_APP=app flask run) and calls baz.bong.run() explicitly. This entry point is appropriate for development, and sets debug=true for the Flask server.

python run.py

Run tests from the terminal

python -m unittest discover -s tests

To dos

• Set up as a package
• make app a module
• add a second module
• run Flask tests
• Run a separate thread for a 'heart beat'
• try a 'real' server