Waitress as Flask server WSGI

Skill - Waitress as Flask server WSGI

Table of Contents

Skills Required

• Flask python module introduction
• Sub mounting a flask application under a URL prefix

Please make sure to have all the skills mentioned above to understand and execute the code mentioned below. Go through the above skills if necessary for reference or revision

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• In this post we will learn how to use waitress as a WSGI (Web Server Gateway Interface) for a flask application

Why use waitress

• The default flask server is not meant for production deployment since it is single-threaded and not highly secure
• Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance

What is Waitress

• Waitress is a pure python WSGI (Web Server Gateway Interface) server
• Waitress can run both on windows and Linux
• Waitress supports multi-threading and sub-mounting of application on a URL prefix
• Maximum number of parallel threads allowed can also be configured easily
• Waitress is often used along with reverse proxies like Nginx and IIS for production deployments

Install waitress

• Waitress is just a python package
• It can be installed in a python environment using pip

python -m pip install waitress

Example Flask server

The following is an example flask server that uses waitress as a WSGI

from flask import Flask
from waitress import serve

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, World with waitress!!!'

if __name__ == '__main__':
    serve(app, host='0.0.0.0', port=50100, threads=1)

sub-mounting application on a URL prefix

• url_prefix option can be used in the serve function to sub-mount a flask application under a URL prefix
• This option is generally used with reverse proxies so that multiple applications can be hosted under multiple URL prefixes

from flask import Flask
from waitress import serve

app = Flask(__name__)

@app.route('/hi')
def index():
    return 'Hello, World with waitress!!!'

if __name__ == '__main__':
    serve(app, host='0.0.0.0', port=50100, threads=1, url_prefix="/my-app")

switch between waitress and default server based on development environment

from flask import Flask
from waitress import serve

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, World with waitress!!!'

mode = "dev"

if __name__ == '__main__':
    if mode == "dev":
        app.run(host='0.0.0.0', port=50100, debug=True)
    else:
        serve(app, host='0.0.0.0', port=50100, threads=1)

Video

The video for this post can be seen here

References

• waitress documentation - https://docs.pylonsproject.org/projects/waitress/en/stable/index.html
• Flask quick-start guide - https://flask.palletsprojects.com/en/2.2.x/quickstart/