Deploying Python Flask Apps with Nginx, Gunicorn, and Supervisor

Python Web Deployment

In web development, many languages compete, but deployment methods are limited. Typically, Nginx acts as a front‑end proxy, forwarding requests to a web service script. Common stack: Nginx + web service + script.

Nginx

Nginx is a high‑performance web server often used as a reverse proxy. A forward proxy sends client requests to the internet via the proxy; a reverse proxy receives external requests and forwards them to internal servers.

Deployment Stack: Nginx + Gunicorn + Flask + Supervisor

We use Gunicorn as the WSGI container, Flask as the Python web framework, and Supervisor to manage processes. The final deployment architecture is: Nginx + Gunicorn + Flask ++ Supervisor.

Create a project

mkdir myproject

Create a Python virtual environment

# Install virtualenv and create an isolated environment
virtualenv venv
cd myproject
virtualenv venv
source venv/bin/activate

Install Flask

pip install flask

Test the Flask installation with a simple app

from flask import Flask
app = Flask(__name__)

@app.route('/')
def index():
    return 'hello world'

if __name__ == '__main__':
    app.run(debug=True)

Run the app

python myapp.py
# Access http://127.0.0.1:5000 to see “hello world”.

Deploy with Gunicorn

# Install Gunicorn
pip install gunicorn

# Freeze dependencies
pip freeze > requirements.txt

# Start the app with Gunicorn (4 workers, listening on port 8000)
gunicorn -w 4 -b 0.0.0.0:8000 myapp:app

Install Supervisor

pip install supervisor
echo_supervisord_conf > supervisor.conf
vim supervisor.conf   # Add Gunicorn process configuration

[program:myapp]
command=/home/rsj217/rsj217/myproject/venv/bin/gunicorn -w4 -b0.0.0.0:8000 myapp:app
directory=/home/rsj217/rsj217/myproject
startsecs=0
stopwaitsecs=0
autostart=false
autorestart=false
stdout_logfile=/home/rsj217/rsj217/myproject/log/gunicorn.log
stderr_logfile=/home/rsj217/rsj217/myproject/log/gunicorn.err

Supervisor basic commands

supervisord -c supervisor.conf          # start Supervisor
supervisorctl -c supervisor.conf status # check status
supervisorctl -c supervisor.conf reload # reload config
supervisorctl -c supervisor.conf start [all|appname]
supervisorctl -c supervisor.conf stop [all|appname]

Enable Supervisor web interface

[inet_http_server]
port=127.0.0.1:9001
username=user
password=123

[supervisorctl]
serverurl=unix:///tmp/supervisor.sock
serverurl=http://127.0.0.1:9001
username=user
password=123

Start Gunicorn via Supervisor

supervisord -c supervisor.conf

Access the web interfaces

http://127.0.0.1:9001   # Supervisor web UI
http://127.0.0.1:8000   # Gunicorn‑served “hello world”

Install and Configure Nginx

# Install Nginx
sudo apt-get install nginx

# Nginx binary: /usr/sbin/nginx
# Configuration directory: /etc/nginx

# Manage Nginx with Supervisor
[program:nginx]
command=/usr/sbin/nginx
startsecs=0
stopwaitsecs=0
autostart=false
autorestart=false
stdout_logfile=/home/rsj217/rsj217/myproject/log/nginx.log
stderr_logfile=/home/rsj217/rsj217/myproject/log/nginx.err

Further automation can be achieved with Fabric (configuration not shown).

Project source: https://coding.net/rsj217/myproject.git