Flask

Basics

Check this[1]

Hello world app:

#!/usr/bin/env python3

from flask import Flask
print(__name__)
app = Flask(__name__)

@app.route('/')

def welcome():
    return 'Welcome'

if __name__ == '__main__':         # When executed on the commandline (build in webserver)
    app.run(host='0.0.0.0',port=5000) # Listen to localhost port 5000, you can also use flask run for options
    #app.run(host='0.0.0.0',port=8080,Debug=True)  # Run in debug mode, listen to all hosts on port 8080

Run the build-in server listening to all

export FLASK_APP=welcome_app.py 
flask run --host=0.0.0.0

welcome_app
 * Serving Flask app "welcome_app"
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)

Now you can browse to <serverIP>:5000

https://code.tutsplus.com/tutorials/creating-a-web-app-from-scratch-using-python-flask-and-mysql--cms-22972

Integrate with nginx

Mayor part is from this site [2].

• Install uwgi-emperor and it's python plugin

Configuration files I used.

• Generic configuration file (/etc/uwsgi-emperor/emperor.ini):

[uwsgi]
# try to autoload appropriate plugin if "unknown" option has been specified
autoload = true
# enable master process manager
master = true
# spawn 2 uWSGI emperor worker processes
workers = 2
# automatically kill workers on master's death
no-orphans = true
# place timestamps into log
log-date = true
# user identifier of uWSGI processes (same as who runs the web-server)
uid = www-data
# group identifier of uWSGI processes (same as who runs the web-server)
gid = www-data
# vassals directory
emperor = /etc/uwsgi-emperor/vassals
plugins = python3

• Application configuration file (/etc/uwsgi-emperor/vassals/welcome.ini)

[uwsgi]
#application's base folder
base = /var/www/flask
#python module to import
app = welcome
module = %(app)
pythonpath = %(base)
#socket file's location
socket = /var/local/uwsgi/%n.sock
#permissions for the socket file
chmod-socket    = 664
#the variable that holds a flask application inside the module imported at line #6
callable = app
#location of log files
logto = /var/log/uwsgi/%n.log
plugins = python3

• Create a virtual webserver (port 80 is save enough if you have a secure front-end server)

server {
	listen 80 ;
	listen [::]:80 ;

	root /var/www/flask;

	server_name <fqdn>;

	location / {
		include uwsgi_params;
        	uwsgi_pass unix:/var/local/uwsgi/welcome.sock;
	}
}

Generate web pages

https://www.idkrtm.com/creating-a-webpage-using-python-and-flask/

https://flask.palletsprojects.com/en/1.1.x/patterns/templateinheritance/#template-inheritance

Microservices and/or more applications on 1 web-server

Still al lot ToDo

For the embedded webserver this works:

#!/usr/bin/env python3

from flask import Flask
print(__name__)
app = Flask(__name__)

@app.route('/')
def root():
    return 'The root of it'

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

@app.route('/welcome')
def welcome():
    return 'Welcome'

if __name__ == '__main__':
    app.run(host='0.0.0.0',port=5000,debug=True)