Orange Sun

Declaring bankruptcy on Advent of Purescript 2023

Vitaly Potyarkin — Tue, 09 Jan 2024 00:00:00 +0300

Advent of Code is a fun challenge and this year I decided to attempt solving it in Purescript. Today I'm declaring this attempt a failure. This post will serve as a postmortem.

Choosing Purescript

Last year I solved my first Advent of Code using Go. It was fun and I …

Benchmarking ssh-agent performance

Vitaly Potyarkin — Wed, 19 Jul 2023 00:00:00 +0300

I have an application idea that would require calling ssh-agent rather frequently - but how many requests per second can it handle?

To answer this question I wrote a small benchmark in Go. It runs a tight loop sending messages for ssh-agent to sign. Turns out the agent is pretty fast …

Many-to-many relationships in Excel data model

Vitaly Potyarkin — Fri, 02 Jun 2023 00:00:00 +0300

This is a quick hack to build many-to-many relationships in Excel data model even though they are not supported out of the box.

Create intermediate calculated table and use DAX to fill it with unique values from related columns on both sides of the relationship:
```
EVALUATE
  FILTER(
    DISTINCT(
      UNION(
        VALUES …
```

A pull request 10 years in the making

Vitaly Potyarkin — Wed, 03 May 2023 00:00:00 +0300

Once upon a time there was a bug in a free software project that annoyed me for long enough that I've learned C to fix it. And it felt good.

Now that we've got a TL;DR out of the way, here is the story.

There is a good torrent …

Advent of Code 2022 was fun!

Vitaly Potyarkin — Thu, 09 Mar 2023 00:00:00 +0300

This was the first year I participated in Advent of Code.

In case you're not familiar with it, AoC is a Christmas themed programming competition consisting of 25 challenges published daily (from December 1st to December 25th). The web site produces personalized puzzle inputs for each user and expects only …

Negotiating down to 100Mbit between two 1Gbit devices

Vitaly Potyarkin — Fri, 29 Jul 2022 00:00:00 +0300

Connecting two gigabit-capable devices via 4-wire UTP cable is an abomination, but sometimes we have to live with it (e.g. when a greedy ISP decides to save a few cents and pulls a cheap cable to your apartment).

The fun starts when the devices try to negotiate Ethernet connection …

"No user exists for uid" when pushing to git repo

Vitaly Potyarkin — Thu, 21 Jul 2022 00:00:00 +0300

Today I tried to automate pushing to a Git repository from a Docker container. And like many others I failed with an error:

$ git push
No user exists for uid 2918
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository …

Pip-installable Pelican themes

Vitaly Potyarkin — Fri, 10 Jun 2022 00:00:00 +0300

Installing Pelican themes the default way is not very pleasant:

You need to invoke a separate CLI tool
You may need to create some symlinks and ensure that they don't go stale the next time you use Pelican
Some people (me) have resorted to git submodules instead of official CLI …

Unexpected workaround for Libvirt VMs with cgroups v2 in Cirrus CI

Vitaly Potyarkin — Wed, 02 Mar 2022 00:00:00 +0300

Today I wrote a commit message that was several screens long. I think it deserves to be a blog post of its own

Update: the commit linked above required some modification to remove flakiness, but the workaround still stands. Diff provided in this blog post was updated to reflect current …

D-Link DIR-825 (rev.B1) throughput test

Vitaly Potyarkin — Mon, 31 Jan 2022 00:00:00 +0300

So, the year is 2022 and I'm still using D-Link DIR-825, rev.B1 as my edge router at home.

Thanks to the power of opensource it is running a modern and secure OS (OpenWRT) long after the manufacturer has abandoned this product. Even though OpenWRT (and Linux in general) has …

Ansible apt module fails to install python3-apt on Debian Testing

Vitaly Potyarkin — Wed, 09 Dec 2020 00:00:00 +0300

I have encountered an unexpected Ansible failure today that turned out to be not a bug.

Ansible apt module had failed to auto install the required python3-apt package - only on Debian Testing. Same playbook worked fine with Debian Stable.

TASK [install some apt packages] *********************************************
[WARNING]: Updating cache and auto-installing missing …

Pegatron Cape 7 nettop (thin client)

Vitaly Potyarkin — Sat, 04 Apr 2020 00:00:00 +0300

Below are hardware details of an outdated compact computer that had since become available for low price on second-hand market. I bought mine for $15 (in March 2020).

This post is inspired by ParkyTowers Thin Client Database - many thanks to David Parkinson for gathering and sharing all that knowledge!

Pegatron …

Running Libvirt (KVM) in Cirrus CI

Vitaly Potyarkin — Tue, 25 Feb 2020 00:00:00 +0300

Up until the middle of 2019 it was very unusual to even expect that any CI service would allow nested virtualization. Those who required such functionality had to maintain their own CI runners on their own infrastructure. Things changed when Google Cloud introduced nested KVM support.

Cirrus CI was probably …

Cirrus CI integration for GitLab projects

Vitaly Potyarkin — Tue, 18 Feb 2020 00:00:00 +0300

Cirrus CI is a relatively new hosted CI service that offers several unique features. It's probably the only CI provider to offer full virtualization (KVM) or FreeBSD runners for free. Currently their business model is centered around GitHub Marketplace and only the projects hosted at GitHub are supported.

Fortunately Cirrus …

Cygwin CI journey

Vitaly Potyarkin — Tue, 28 Jan 2020 00:00:00 +0300

Setting up Cygwin CI environment for testing one of my projects took more than fifty trial-and-error attempts - that's why I think it will be useful to leave some written notes on the issues I've encountered. Here is the end result - GitHub CI running some Makefile tests in Cygwin.

Cygwin gotchas …

Don't blindly trust Docker for the selfhosted stuff

Vitaly Potyarkin — Mon, 27 Jan 2020 00:00:00 +0300

It is my strong belief that you shouldn't go crazy with all-things-docker when deploying selfhosted services at home. Online forums, especially r/selfhosted, seem to foster an opinion that providing a Dockerfile or better yet a docker-compose.yml or even prebuilt public images on Docker Hub is an acceptable way …

Manage Python virtual environment from your Makefile

Vitaly Potyarkin — Tue, 01 Oct 2019 00:00:00 +0300

I often use Makefiles not just as a build tool but as a handy way to execute sequences of commands. The commands I've found myself executing again and again lately are the ones to manage Python virtual environments:

Create new venv
Update pip to the latest version that enables all …

Cygheap base mismatch in Git for Windows

Vitaly Potyarkin — Mon, 26 Aug 2019 00:00:00 +0300

This error has haunted me for several months:

4 [main] head (6660) C:\...\usr\bin\head.exe:r
*** fatal error - cygheap base mismatch detected - 0x612C7410/0xAF7410.

This problem is probably due to using incompatible versions of the cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility …

On dotfiles management

Vitaly Potyarkin — Tue, 30 Jul 2019 00:00:00 +0300

This will be yet another description of dotfiles management by some random person on the Internet. I will try to explain what my setup is like and why it is that way.

If you're not yet using version control software for your configuration files I strongly encourage you to start …

Installing One by Wacom in Debian Stretch

Vitaly Potyarkin — Wed, 22 Aug 2018 00:00:00 +0300

I believe there are many people who run Debian Stable as their main desktop OS. This article is a short how-to on enabling newer hardware in Debian Stable without switching to another version or distribution.

NOTE: This article was written in 2018, new Debian Stable (Buster) has been released since …

Enhanced file path completion in bash (like in zsh)

Vitaly Potyarkin — Sat, 14 Jul 2018 00:00:00 +0300

Zsh offers a lot of significant improvements over traditional shell experience. Some of those can also be implemented in bash, but others are not. For a long time I've thought that advanced file path expansion is something that can't be done in bash. Today I prove myself wrong.

Background

When …

Liberating effect of Ansible

Vitaly Potyarkin — Tue, 26 Jun 2018 00:00:00 +0300

Maintaining two or three Linux machines is not that hard of a task. For many years I have thought it was not worth the effort to automate - regular backups and version-controlled configuration files seemed to be just enough.

And then Ansible had blown my mind.

History

It all started with …

Accidental submersion into web development

Vitaly Potyarkin — Sat, 16 Jun 2018 00:00:00 +0300

The Library Problem

I love reading books. My wife loves reading books. We enjoy shopping for books and we live a ten minute commute away from a huge used books store. That means we have a lot of books. Like, really a lot. A little more than one thousand.

We …

Excel as a CSV editor (with VBA)

Vitaly Potyarkin — Fri, 01 Jun 2018 00:00:00 +0300

One might think that Excel is a decent CSV editor as it is, but it's not. It is a very capable CSV reader, I do not dispute that. When it comes to writing though, Excel does not match what you'd expect from a mature application:

It might change the delimiter …

Why software translation is a waste of time

Vitaly Potyarkin — Thu, 24 May 2018 00:00:00 +0300

Disclaimer: I am not a professional software developer, and my opinion might not be as authoritative as yours.

My native language is not English and since my first encounter with computers I have used multiple localized and non-localized computer programs. All these years of "user experience" have led me to …

Unit testing in Power Query M Language

Vitaly Potyarkin — Sun, 01 Apr 2018 12:00:00 +0300

As your code base gets bigger, test automation becomes more and more important. This applies to any development platform, including Power Query / PowerBI. If you reuse your code and improve some low level function later, test automation allows you to make sure your changes did not break anything that depends …

Getting started with LibPQ

Vitaly Potyarkin — Sun, 01 Apr 2018 00:00:00 +0300

This is a step by step guide to getting started with LibPQ, an illustrated version of "Installation and usage" section of the official documentation.

Installation

LibPQ source code

The source code of the library has to be present in each workbook that uses it.

Create a new blank query: Data …

Roads and Bridges - sustaining modern digital infrastructure

Vitaly Potyarkin — Fri, 23 Feb 2018 00:00:00 +0300

This week I have stumbled upon a very thorough review of existing problems and hidden costs of sustaining modern (open source) digital infrastructure. Here it is: Roads and Bridges - The Unseen Labor Behind Our Digital Infrastructure by Nadia Eghbal.

The essay was created with support from the Ford Foundation and …

Expanding Power Query standard library - introducing LibPQ

Vitaly Potyarkin — Wed, 03 Jan 2018 00:00:00 +0300

Power Query formula language (also known as M language) is a very capable yet not very flexible tool. It lacks some features taken for granted by developers who are used to other programming languages such as compatibility with version control systems, extensibility by third-party libraries, etc.

That is why I …

Loops in Power Query M language

Vitaly Potyarkin — Tue, 31 Oct 2017 00:00:00 +0300

Power Query Formula Language (also known as M language) is sometimes difficult to get your head around. This article explains how someone familiar with loops in other programming languages can approach the same concept in M language.

First of all let's look at the definition given by Microsoft:

The Power …

Temporary virtual environment for Python

Vitaly Potyarkin — Thu, 05 Oct 2017 16:50:00 +0300

Using Python on Windows does not come as naturally as on Unix-like systems, so any help is appreciated.

I wrote a batch script to automate creation, setup and deletion of Python virtual environment. This can come in handy when you want to test something in a clean env, or to …

Execute the same git subcommand in all local repositories

Vitaly Potyarkin — Thu, 05 Oct 2017 15:40:00 +0300

If you work with more than one git project simultaneously, you often need to do the same maintenance tasks in each cloned repository:

check if there are some changes waiting to be pushed,
check remote URLs for all repos (e.g. when considering to switch from HTTPS authentication with GitHub …

Portable development setup for Python on Windows

Vitaly Potyarkin — Wed, 20 Sep 2017 00:00:00 +0300

WinPython

https://winpython.github.io/

All-in-one distribution which comes with many difficult-to-build packages preinstalled. And their ...-Zero version is great for thumb drives!

Pip works just fine, but installing packages that require C compiler is always a pain on Windows. May be I should look into conda and see if …