Flask with gunicorn

Flask is a minimalist web framework. Although it has build-in a wsgi (Web Server Gateway Interface) server, but this server is not suitable for production. Popular solution is gunicorn.

Flask App

Let’s create simple flask app. Create a file simple_app.py with:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello World!'

Run with gunicorn

gunicorn simple_app:app

If you use virtualenvs and have gunicorn installed globally you may need to run:

$VIRTUAL_ENV/bin/gunicorn simple_app:app

Gunicorn has more options. In order to run it with, for example, 4 workers, on 5000 port, and put logs in files you can run:

$VIRTUAL_ENV/bin/gunicorn wsgi:app \
    --bind 0.0.0.0:5000 -w 4\
    --access-logfile gunicorn-access.log\
    --error-logfile gunicorn-error.log

Then you can see logs with, for example,

tail -f gunicorn-access.log