WIP

Introduction

Since I often write web servers using Flask, I will summarize the pages that I often refer to. I think it will be a collection of links for the time being, but if I have time, I would like to add more content. (It's about time to use FastAPI)

Main environment

Python 3.8 (pipenv, pyenv)
Flask
MySQL 8.0 - SQLAlchemy
gunicorn
Nginx
(Docker, docker-compose)
Ubuntu 20.04 LTS

Around Flask

About SECRET_KEY For official tutorials, it's best to use ʻos.urandom (12) `, which is a ** anti-pattern ** When running gunicorn with multiple Workers, Session and CSRF Protection (Flask-WTF) do not work properly because different SECRET_KEY is set depending on the worker.
Convenient Extensions
socket.io

session

Browser session

In Vanilla Flask with no plugins

cookie session
base64encode It has become. The official Doc states that ʻapp.Config should be set to SecretKey`, but this only uses this key in the hash calculation to prevent tampering with the contents stored in session. , The contents of session itself are not encrypted.

server session You need to install a plugin. Backend options for saving sessions include Redis, other NoSQL, FileSystem, SQL, etc.

As a famous plug-in

and so on. FLask-Session accesses the backend that holds the Session from within Flask, but Beaker acts as middleware for the WSGI (eg Gunicorn) used. The latter also provides a Cache function. It has been confirmed that Flask-Session does not work properly when SQLAlchemy is specified as the backend (that is, SQL). (As of May 2020.5)

logging Flask and its plugins often provide a log output feature. To capture the output log with the Flask main unit log handle and output it

import logging
from flask.logging import default_handler #Log handler for flask body
#Other import etc.
from flask_cors import CORS

def create_app():
    # init_Various processing such as app
    #Here, the plugin you want to log`flask_cors`To
    cors_err_lggr = logger.getLogger('flask_cors')
    #Most plugins have the name of the built-in logger__name__Is it specified in?
    cors_err_lggr.setLever(logging.DEBUG)
    #Added default log handler
    cors_err_lggr.addHandler(default_handler)
    
    #Other processing

    return app

test

Around DB (MySQL, SQLAlchemy)

SQLAlchemy relationship official Doc
[SQLAlchemy many: many relation commentary article](https://momijiame.tumblr.com/post/27327972441/python-%E3%81%AE-or%E3%83%9E%E3%83%83%E3% 83% 91% E3% 83% BC-sqlalchemy-% E3% 82% 92% E4% BD% BF% E3% 81% A3% E3% 81% 9F% E3% 83% AA% E3% 83% AC% E3 % 83% BC% E3% 82% B7% E3% 83% A7% E3% 83% 8A% E3% 83% AB% E3% 83% 9E% E3% 83% 83% E3% 83% 94% E3% 83 % B3% E3% 82% B0% E5% 9F% BA% E6% 9C% AC-4)
Detailed explanation of SQLAlchemy relation parameters
~~ Variant to get independent columns existing in N: N intermediate table ~~

When setting independent columns (columns that are not Foreign Keys) in the intermediate table of many: many, it is better to use ʻassociation_proxy than to use relation`. Official Doc for association_proxy, with implementation example

Around Nginx, Gunicorn

Around Docker

Around deployment

Fabric2 seems to be good?

Official Document It feels like Capistrano or Deployer Explanatory article 1 Explanatory article 2

in conclusion

No, FastAPI Isn't it good?

[DOCKER] Notes and reference books when creating Web services with Flask