Author: Miguel Grinberg


The Ultimate Guide to Python Decorators, Part I: Function Registration

One of the signatures of the Flask framework is its clever use of decorators for common application tasks such as defining routes and error handlers. Decorators give a very concise and readable structure to your code, so much that most Flask extensions and many other Python packages follow the same pattern and expose core parts of their functionality through decorators.

Today I'm starting a series of in-depth posts about different ways in which you can incorporate custom decorators into your Python applications. In this first part I'm going to show you how to create simple decorators that register functions as callbacks for application-specific events.



MicroPython and the Internet of Things, Part II: Hello, MicroPython!

In this chapter you are going to learn how to install and use MicroPython on your ESP8266 microcontroller board.

If you want to see me and hear me explain everything in this tutorial, I encourage you to purchase the video version from my Courses site. Not only it will make for a better learning experience, but you'll also be supporting my effort in keeping my blog updated with relevant content. Thank you!



MicroPython and the Internet of Things, Part I: Welcome

Welcome to my MicroPython and the Internet of Things tutorial!

In this first part I want to give you a brief overview of what this tutorial is about, and more importantly, provide you the list of components that you are going to need.



Introducing My MicroPython Tutorial

I'm happy to announce a new multi-part tutorial that I will soon begin publishing on this blog and several other platforms. The tutorial is titled MicroPython and the Internet of Things and is a beginner tutorial that will introduce you to the exciting world of microcontrollers and small-form Internet enabled devices.



Running a Flask Application as a Service with Systemd

Posted by Miguel Grinberg under Python, Flask.

When you deploy your application on a server, you need to make sure the application runs uninterrupted. If the application crashes, you'd want it to automatically restart, and if the server experiences a power outage, you'd want the application to start immediately once power is restored. Basically what you need is something that keeps an eye on the application and restarts it if it ever finds that it isn't running anymore.

In previous tutorials, I showed you how to implement this using supervisord, which is a third party utility written in Python. Today I'm going to show you a similar solution based on systemd, which is a native component in many Linux distributions including Debian derivatives such as Ubuntu and RedHat derivatives such as Fedora and CentOS.



Nested Queries with SQLAlchemy ORM

Posted by Miguel Grinberg under Database, Python.

One of the most rewarding aspects of having a popular course online is that from time to time I get a question that forces me to learn something new. The other day a reader asked me how they can write a database query with an unusual ordering, and I had to stop for a minute (okay, it was more like half an hour) to think about how to do it within the context of a Flask and Flask-SQLAlchemy application. Are you ready to see some advanced SQLAlchemy action?



Unit Testing Applications that use Flask-Login and Flask-SocketIO

One of the useful features of my Flask-SocketIO extension is the test client, which allows you to write Socket.IO unit tests. A long time limitation of the test client was that it did not see cookies set by Flask, such as the user session. This complicated writing Socket.IO tests for applications that require authentication, because most authentication mechanisms write something to the user session or a custom cookie. The use case that caused pain to a lot of developers was applications that use Flask-Login combined with Flask-SocketIO. To unit test such an application you had to resort to weird tricks such as mocking the current_user variable.

I recently came up with a solution to this problem, so I'm glad to report that this limitation is now a thing of the past. In this short article I want to show you how to set up your project to take advantage of the new cookie support in the Socket.IO test client.



How To Make Python Wait

For many types of applications, at times it is necessary to pause the running of the program until some external condition occurs. You may need to wait until another thread finishes, or maybe until a new file appears in a directory on disk that is being watched.

In these and many other situations you will need to figure out a way to make your script wait, and this isn't as easy as it sounds if you want to do it properly! In this article I'm going to show you a few different ways to wait. I'm going to use Python for all the examples, but the concepts I'm going to present apply to all programming languages.



SSH Security For Teams

Posted by Miguel Grinberg under Cloud.

Authentication Tokens

There are plenty of tutorials that cover the basic measures you need to take to secure a Linux server, including my own. What usually falls outside the scope of these tutorials is what other steps are recommended for a server that is going to be accessed by multiple people, such as a group of developers all working together as a team. Group access to a server introduces some challenges, as you will need to implement procedures to grant and revoke access as team members come and go, and do so without any compromises on security.



Coding on a Chromebook Revisited

Posted by Miguel Grinberg under Programming.

Google Chromebook

It's been over a year since I wrote my guide on setting up a cheap Chromebook for web development. In that article, I presented three different ways to install a Linux distribution instead of, or sometimes alongside ChromeOS, the native Chromebook operating system. These three methods were all a bit hacky. One required running a heavily sandboxed Android app, while for the other two you had to put the machine in developer mode, which bypasses some of the security measures that make the Chromebook one of the most secure laptops you can find.

Since I wrote that article in September 2017 there's been a new development. Now there is a fourth method of running a native Linux distribution, available to most Chromebook models from the last few years. What makes this new method interesting is that it is an officially supported feature of ChromeOS, so there is no need to activate developer mode, and no need to make concessions on the highly regarded Chromebook security model. This method is based on container technology, and is known by the project name Crostini.