We look into how to set up WireGuard on a Linux system. In this case, we use Debian in order to create a tunnel between two nodes using WireGuard. The setup is quite easy because WireGuard has strong opinions about what should be available and that means that the setup doesn’t have that many things…

We look into writing a QR code generator in java from scratch. QR Code has a lot of different technologies and strategies in order to create a readable and unambiguous code. Writing an implementation in Java needs to be done in multiple steps and have a lot of fun and interesting challenges.

After my kid asked me to download and install an auto-clicker, I saw this as a teachable moment to build one in Java. I could talk about the different concepts Java offers and also explore a new API in the Java API. Source code: package org.ea; import javax.swing.*; import java.awt.*; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import…

Doing a manual upgrade of my Ceph cluster. In the same process, I get the Debian operating system upgraded that my Ceph cluster is running on. The new version of Ceph called Pacific requires some extra measures and when you’ve updated you can’t go back.

In this video, I look into installing and enabling orchestration using cephadm. Then I will perform an automatic upgrade with cephadm. I talk about my findings and go through all the steps.

We look into lambda functions in java using example code and understand what functions could help you with. Java has many new concepts that could help you, and lambda is just one of them. For example, you could create Suppliers that give you a value, Consumers that use a value, and then functional interfaces.

We look into writing a custom log4j appender in java and how to send you to log messages with an appender to RabbitMQ. Writing a custom appender is challenging due to performance considerations.

We look into logrotate on Debian and figure out how timers actually work with a system with cron installed and configured. This was a bit of a gotcha for me, so hopefully, this will help you when you configure logrotate and want to use the timers in Debian to set a correct time.

I took a look at the service provider interface in java. This is a needed interface to build simple services using easy building blocks to extend and improve programs or libraries. We will create one example and also look into some tools that use this interface already.

In this tutorial, I go through how to create a video in java. Using the framework Xuggle we can create a video file containing a stream of images. But you can use any BufferedImage to create these frames, so this library is super flexible and even support audio.