1. Notes
  2. Install dependencies
  3. Python environment
  4. Python Application
  5. Create WSGI entrypoint
  6. Create Systemd service file for Flask Application
  7. Configure Nginx as reverse proxy
  8. Support Materials

Notes

Configurations for using a Flask application using Gunicorn and Nginx. The application will respond to http and https requests over port 5000.

Install dependencies

> sudo apt install python3-pip python3-dev python3-venv nginx

Python environment

> python3 -m venv env
> source env/bin/activate
> pip3 install flask gunicorn

Python Application

>vim ~/project/app.py


from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
    return "Welcome to Flask Application!"
if __name__ == "__main__":
    app.run(host='0.0.0.0')

Create WSGI entrypoint

> vim ~/project/wsgi.py

from app import app
if __name__ == "__main__":
    app.run()

> deactivate

Create Systemd service file for Flask Application

> vi /etc/systemd/system/flask.service

[Unit]
Description=Gunicorn instance to serve Flask
After=network.target
[Service]
User=root
Group=www-data
WorkingDirectory=/home/<user>/project
Environment="PATH=/home/<user>/project/env/bin"
ExecStart=/home/<user>/project/env/bin/gunicorn --bind unix:/home/<user>/project/request.sock wsgi:app
[Install]
WantedBy=multi-user.target


> chown -R root:www-data /home/<user>/project
> chmod -R 775 /home/<user>/project
> systemctl daemon-reload
> systemctl start flask
> systemctl enable flask
> systemctl status flask

Configure Nginx as reverse proxy

> vim /etc/nginx/sites-available/flask.conf

server {
  listen <server_ip>:5002 ssl http2;
  listen <server_ip>:5001;

  ssl_certificate /home/<user>/project/cert.pem;
  ssl_certificate_key /home/<user>/project/key.pem;

  access_log /home/<user>/project/rest_api.access.log;
  error_log /home/<user>/project/rest_api.error.log;



  location / {
    include proxy_params;
    proxy_pass http://unix:/home/<user>/project/request.sock;
   }

}


> vim /etc/nginx/nginx.conf

At the end of file add:

stream {
    upstream http {
        server <server_ip>:5001;
    }

    upstream https {
        server <server_ip>:5002;
    }

    map $ssl_preread_protocol $upstream {
        default https;
        "" http;
    }

    # SSH and SSL on the same port
    server {
        listen 5000;

        proxy_pass $upstream;
        ssl_preread on;
    }
}



> sudo ln -s /etc/nginx/sites-available/flask.conf /etc/nginx/sites-enabled

> nginx -t
> systemctl restart nginx

Support Materials

RosehostingKeval Nagdamiguelgrinberg.com