All articles tagged #python

"How to start programming in Go and for Kubernetes?" - the question I often get from fellow DevOps people. This is a tricky one. And I don't have a universal answer to it. However, I do have some thoughts to share.

But first, let me tell you my own story.

In my case, it was rather an evolutionary step - I'd been developing software for almost 10 years by the time I started coding for Kubernetes. I'd also been (sporadically) using Go for some of my server-side projects since probably 2015. And around 2019, I started my transition to, first, SRE and, then, Platform Engineering. So, when I decided to get my hands dirty with Kubernetes controllers, it was just a matter of joining the right team and picking up the Kubernetes domain. Luckily, I had a good candidate on my radar, and that required just an internal transition from one team to another.

However, based on my observations, for many contemporary DevOps engineers, the direction of the desired transformation is often inverse. From Ops to Dev (preferably, for Ops).

Since your background and experience may vary, instead of giving a concrete piece of advice here, I'll try to explain how I'd approach the problem given different levels of proficiency with the technologies.

Read more

When I was a kid, I used to spend days tinkering with woodworking tools. I was lucky enough to have a wide set of tools at my disposal. However, there was no one around to give me a hint about what tool to use when. So, I quickly came up with a heuristic: if my fingers and a tool survived an exercise, I've used the right tool; if either the fingers or the tool got damaged, I'd try other tools for the same task until I find the right one. And it worked quite well for me! Since then, I'm an apologist of the idea that every tool is good only for a certain set of tasks.

A programming language is yet another kind of tool. When I became a software developer, I adapted my heuristic to the new reality: if, while solving a task using a certain language, I suffer too much (fingers damage) or I need to hack things more often than not (tool damage), it's a wrong choice of a language.

Since the language is just a tool, my programming toolbox is defined by the tasks I work on the most often. Since 2010, I've worked in many domains, starting from web UI development and ending with writing code for infrastructure components. I find pleasure in being a generalist (jack of all trades), but there is always a pitfall of spreading yourself too thin (master of none). So, for the past few years, I've been trying to limit my sphere of expertise with the server-side, distributed systems, and infrastructure. Hence, the following choice of languages.

Read more

What is a web server?

Let's start by answering the question: What is a web server?

First off, it's a server (no pun intended). A server is a process [sic] serving clients. Surprisingly or not, a server has nothing to do with hardware. It's just a regular piece of software run by an operating system. Like most other programs around, a server gets some data on its input, transforms data in accordance with some business logic, and then produces some output data. In the case of a web server, the input and output happen over the network via Hypertext Transfer Protocol (HTTP). For a web server, the input consists of HTTP requests from its clients - web browsers, mobile applications, IoT devices, or even other web services. And the output consists of HTTP responses, oftentimes in form of HTML pages, but other formats are also supported.

Read more

Python is booming and Flask is a pretty popular web-framework nowadays. Probably, quite some new projects are being started in Flask. But people should be aware, it's synchronous by design and ASGI is not a thing yet. So, if someday you realize that your project really needs asynchronous I/O but you already have a considerable codebase on top of Flask, this tutorial is for you. The charming gevent library will enable you to keep using Flask while start benefiting from all the I/O being asynchronous. In the tutorial we will see:

• How to monkey patch a Flask app to make it asynchronous w/o changing its code.
• How to run the patched application using gevent.pywsgi application server.
• How to run the patched application using Gunicorn application server.
• How to run the patched application using uWSGI application server.
• How to configure Nginx proxy in front of the application server.
• [Bonus] How to use psycopg2 with psycogreen to make PostgreSQL access non-blocking.

Read more

In the previous article, we learned how to implement a simple but workable event loop. However, programs which are supposed to be run by the event loop are full of callbacks. This is the usual problem of event-loop-driven environments. When business logic becomes reasonably complicated, callbacks make program's code hardly readable and painfully maintainable. And the callback hell begins! There is plenty of ways to deal with the artificial complexity arose due to callbacks, but the most impressive one is to make the code great flat again. And by flat, I mean callback-less and synchronous-like. Usually, it's done by introducing async/await syntactic feature. But every high-level abstraction is built on top of some basic and fundamental ideas. Let's check the async/await sugar out and see what exactly happens under the hood.

Read more