All articles on Programming

I've been working on adding basic images support to my experimental container manager and to my surprise, the task turned to be more complex than I initially expected. I spent some time looking for ways to manage container images directly from my application code. There is plenty of tools out there (docker, containerd, podman, buildah, cri-o, etc) providing image management capabilities. However, if you don't want to have a dependency on an external daemon running in your system, or you don't feel like shelling out for exec-ing a command-line tool from the code, the options are at best limited.

I've reviewed a bunch of the said tools focusing on the underlying means they use to deal with images and at last, I found two appealing libraries. The first one is github.com/containers/image library "[...] aimed at working in various way with containers' images and container image registries". The second one is github.com/containers/storage "[...] which aims to provide methods for storing filesystem layers, container images, and containers". The libraries are meant to be used in conjunction and form a very powerful image management tandem. But unfortunately, I could not find a sufficient amount of documentation, especially how to get started kind of it.

Without the docs the only way to learn how to use the libraries for me was to analyze the code of their dependants (most prominently - buildah and cri-o). It took me a while to forge a working example which is capable of:

• pulling images from remote repositories;
• storing images locally;
• creating and mounting containers (i.e. writable instances of images).

In the rest of the article, I'll try to show how to use the libraries to perform the said task and highlight the most interesting parts of this journey.

Disclaimer: This is by no means an attempt to fully or even partially document the libraries!

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I spent half a year deep-diving into the world of containers and their orchestration. I have been enjoying it very much and learned a lot. On my journey, I need to tackle lots of interesting and specific concepts. But there is one commonality almost every project in this area possesses. When it comes to containers - the Go programming language is ubiquitous!

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In the previous articles, we discussed the scope of the container runtime shim and drafted the minimum viable version. Now, it's time to move on and have some fun with more advanced scenarios! Have you ever wondered how docker run -i or kubectl run --stdin work? If so, this article is for you! We will try to replicate this piece of functionality in our experimental container manager. And as you have probably guessed, the container runtime shim will do a lot of heavy lifting here again.

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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.

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Regardless of whether it's the end of the calendar decade or not it's the end of a programming decade for me. I started early in 2010 and since then I've been programming almost every day, including weekends and vacations. This was a really exciting period in my life and I realized that it's been a while since 2010 only recently. So, I decided to put into words some of my learnings from that time. Warning: the content of this article is highly opinionated and extremely subjective.

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