Certificates are a fundamental part of the Internet’s security. At least since Let’s Encrypt, a free and automated Certificate Authority, has started its service, SSL is nearly used everywhere. To avoid Certificate issues and possible service outages, it’s a good idea to monitor the SSL certificates used by your services, especially as Let’s Encrypt certificates have a short lease time of 90 days.

I’m using Prometheus to monitor my infrastructure, and for Prometheus there are multiple ways to get started. Most of the tutorials and posts of the internet will cover the case of expired certificates, and it’s pretty easy to achieve. I prefer to use Telegraf, a plugin based metrics collector that also provides Prometheus compatible outputs, instead of dedicated Prometheus exporters. To monitor SSL certificates, I’m using the x509_cert input plugin of Telegraf that provides a metric called x509_cert_expiry which can be utilized to write simple alerting rules. That’s actually pretty cool already, as Prometheus will send out alerts a few weeks before the certificates would expire in case there is a problem within the automatic renewal process.

If you work with a lot of Git repositories on a regular basis, you’re bound to run into the situation where you need to make changes to multiple repositories sooner or later. While it would be possible to run your Git commands in a shell loop over everything repositories, it is often tedious to type the command or remember the correct syntax.

We all use many different tools every day e.g. for our work, automation or better productivity. In the series “Toolbox” I would like to present such applications that have made my day-to-day work so much easier. All applications are free and open source software developed by big tech companies as well as lovingly handcrafted hobby projects. If you also know an awesome tool that has changed your life, I would love to hear from you on Mastodon.

In the last days I worked on a suitable setup for a Drone CI server to support multi-arch builds. While the setup for common x86 Drone runners is easy, working with setups for ARM, especially ARM32, is a bit tricky. The easiest way would be to have native servers of the respective architecture available. However, it’s difficult to find hosting offers for ARM at all - for ARM32 this seems almost impossible. I decided to use Amazon EC2 ARM64 servers, they are relatively cheap and can also be used as a private customer.

In my last article about modernizing a Game Boy Advance, one of my complaints was the ugly coloring of old Game Boy Classic games and I thought about buying an additional Game Boy Classic. But first I wanted to check if there was a mod for the Game Boy Advance to fix this problem.