In this post, I'll tell you about 3 ways of securing processes on Linux: Seccomp, AppArmor and Linux Capabilities. I'll use examples and make them easy to reproduce on your computer using Docker, so you can get your hands dirty and get a feel for the

I’ve been learning about Kubernetes recently, a computer program used by software engineers to create websites. To make it easier to understand what Kubernetes does and how it works, let’s talk about food. In order for a restaurant to work well during rush hour, the employees have a

A few days ago, I wanted to install Windows on an external SSD, connected via USB. The goal was having a dual boot without taking up space from the internal SSD of my laptop. I found no good solution but thought I’d write down what I tried regardless. Creating

Recently, I troubleshot build errors during deployments with Heroku. Heroku slug size growing The Heroku build was getting bigger with every release, and we were seeing errors such as: Warning: Your slug size (446 MB) exceeds our soft limit (300 MB) which may affect boot time. I had to regularly

For years, I’ve been taking pictures of all kinds of things with my smartphone. The photo above, which is wall in Malta is just one example. Currently, I have all these pictures in a folder without any kind of sorting. It has become large enough that I have no

I’ve been trying to migrate this blog, currently built on Hugo, to Ghost. The goal is to migrate a bunch of markdown files located in content/codebase/*.md to the format accepted by Ghost, all the while preserving URLs, meta descriptions and images without manual work for each post.

In August 2018, I wrote about the challenges of moving from AWS to Heroku. A new challenge has presented itself on the same website since then: a large number of request timeouts at unpredictable times during the day. What we saw in Heroku For the last few months, we’ve

Over the past 3 years, I feel like I’ve seen a lot of interesting errors cases happen as a full-stack web developer, focusing on PHP-driven backends. Pretty much any error that I think would not happen to me ended up happening anyway. Murphy’s law. Here are some of

Recently, I’ve been looking into performance issues on an SQL-based search feature. The website in question paginates with Symfony’s PagerFanta Bundle. It seems that optimizing this bundle for use with large table is a somewhat common issue. Use IN instead of = xxx OR This one is simple enough.

Recently, I’ve been migrating a website from AWS to Heroku to reduce the maintenance burden of AWS EC2 instances and make the website more reliable. Planning for failure Before migrating the servers, I make sure there was an easy way to switch back to the old infrastructure, just in

Just a quick note in /bin/sh. It doesn’t always point to the same underlying binary. /bin/sh can point to any other shell /bin/sh is often a symlink to /bin/bash. But on newer Ubuntu /bin/sh refers to /bin/dash. My laptop, which runs Arch Linux,

Most PHP projects eventually pull in open source libraries from Composer. All of these Composer dependencies must be updated regularly to avoid security holes or incompatibility issues with new software. I do a couple of things before updating a dependency to make sure the update doesn’t break anything. Figuring

Here are some of the things I think are useful to keep memory usage under control in Symfony commands that process large databases. Batching Two naive approaches to looping over all contents of a database would be: * Select all data at once and migrate it in one run: the network

Here’s what I understand from data science after taking Coursera’s crash course on data science from Johns Hopkins University. What data science is Data science is the science of answering questions with data. Use of statistics in data science It usually involves the use of statistics, which are

I’m trying to better understand where endianness comes from and its impacts on code performance. Here’s what I’ve got so far. Description First, here’s how integer 0x0A0B0C0D, or 168496141, is stored in little-endian and big-endian. In little-endian, the least significant bytes come first: address | byte value

I’m looking to improve test coverage for Rooster, a simple password manager for geeks I’ve been building with the help of the community. Why add tests now A few days ago, contributor Dmitry V. Roenko updated deprecated serialization code adds unit tests to his work. Oleg Yamnikov, another

For some time, I’ve wanted a backup of my dotfiles, just in case. Backing up configuration files I could keep a Git repository, but currently, a simple folder on my laptop, for which I have complete backups via restic, is good enough for me. I rarely change dotfiles, I

I’m setting up my Thinkpad with Arch Linux and full-disk encryption. Veracrypt The first encryption method I look at is Veracrypt. During a job interview, a company asked me questions about Veracrypt. I didn’t know what it was. The interviewer told me it had this feature called “encrypted

I’m taking the deep dive into x86-64 assembly. Or at least I’m dipping my toes. Introduction to assembly Because my computer has a 64 bits CPU, the easiest way to get started is probably to use the assembly that works on my computer. That would be x86-64, although

I’m learning about ELF, the binary file format for Linux, BSD and others. It is full of interesting information and serves as a good introduction to assembly programming. High level overview My first search leads me to the Wikipedia page about ELF. It says something about “tables” and “sections”