My setup implies that I have 3 almost identical application nodes (running as containers) that are part of a cluster and they need to be mapped to different external IPs (not part of the docker ingress network) because they are added in a cluster configuration external to docker. The default behavior of port binding is… Read More »
As you are aware, no service runs alone on some server. You always have to take into account the communication layer between your server and client services. One of the most tricky thing a lot of people overlook is the “housekeeping” of the communication layer. In a properly setup enterprise environment your communication layer (firewalls,… Read More »
I have a nice mechanical keyboard “VicTsing® Mechanical PC Gaming Keyboard 87” with German layout, but I prefer my Windows 10 in English. The quick solution the use the keyboard was to add also German language support but kept English as default language. Then the most annoying and frustrating thing kept happening: 1. I selected… Read More »
Following is a simple and easy way to do a consistent back-up of the /home directory (usually mounted in a separate partition) on a running system. We do not have the luxury of being able to stop the operations of a server and unmount the home partition to make sure no changes are done during… Read More »
Sometimes really simple questions are hard to answer. One day I got the question from a coworker: “How do I know if some installed RAM is ECC or not”. The easiest way is to use dmidecode command that dumps in Linux all the system characteristics. But because I had no idea how to see if… Read More »
Lately after one of the updates of docker binaries I started to have a strange issue in a Docker Swarm setup configured here. Services were no longer able to see each other if they were running on different nodes. If two services were running on the same swarm node there was no issue. This is… Read More »
Sometimes you get a CA certificate in DER format and some application requires it in a PEM format. OpenSSL to the rescue: # openssl x509 -inform der -in myCA.der -out myCA.pem
At some point an increase in size of the replicated resource is needed. This can be caused by an increase in data retention times or an increase of transaction numbers affecting that resource. If the backing block devices can be grown while in operation (online), it is also possible to increase the size of a… Read More »
Even when you think that you know something well enough you discover that there are some corner cases you never encountered. This is the main reason I like IT system administration tasks, you never get bored. This post is about one of this corner cases in a DRBD setup described in post #DRBD based disk… Read More »
CASE 1: If you use multi-stage docker builds you will end up with lots of un-tagged images. The proper way to clean the intermediary leftover images is: docker rmi $(docker images -f “dangling=true” -q) CASE 2: If you want to clean up all the old images for which you no longer have any instantiated container… Read More »