When a Prometheus alerting rule fires, the Prometheus server sends a notification to the Alertmanager, which is then responsible for processing that alert further, i.e. by routing it to an appropriate alerting channel (e-mail, Slack, ...). In order to test the Alertmanager configuration, it is useful to trigger alerts directly …
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Checking Whether a Process Exists
On Linux/Unix systems, there's occasionally the need to check whether a process is running. Some people use it for simple status checks or when building their own lifecycle scripts for startup and shutdown. I don't think it's a particularly good practice these days because all of this can be …
read moreDetecting Security Upgrades on Ubuntu
In my article on unattended upgrades I described how to set up an Ubuntu system to install security upgrades automatically. This is convenient for small setups, but in an enterprise environment you typically want to perform some QA before applying the change. A better solution is to have your monitoring …
read moreVim File Type Configuration
Vim has been my primary text editor for more than 15 years, but even though I use it on a daily basis, my configuration hasn't changed much over time. When I set up a new workstation, I stumbled upon the filetype plugin that I wasn't aware of. Using this plugin …
read moreKeeping Your Server Secure With Unattended Upgrades
When operating servers, you're responsible for keeping them up to date with the latest security fixes. Ubuntu comes with a mechanism that installs updates automatically so you don't have to worry about it. Obviously, this is meant for personal servers operated by hobbyists where convenience is more important than availability …
read moreLiving in the Future with IPv6
Installing Oracle's JDK on Debian/Ubuntu
Due to licensing issues, Linux distributions don't ship Oracle Java packages anymore. In many cases, that doesn't matter since you can just use OpenJDK. But if you do need Oracle's JDK, Debian packages are a bit more convenient than handling tarballs because they integrate nicely with the rest of the …
read moreManaging Docker Container Updates
When running a Debian/Ubuntu-based server, it's relatively easy to figure out whether updates need to be installed. Tools based on apt work very well in this regard and even offer advanced features like unattended updates. Not so with services running in Docker containers.
When working with Docker, you typically …
read moreConverting Images to ASCII Art
I've been playing with Docker a lot lately. Docker is a tool for creating lightweight virtual environments based on Linux containers. They are extremely useful for running services, but you can also use them for running one-off tasks that you don't want to run on the host system directly. Since …
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