Category Archives: DataCenter

Bind #Docker container ports to virtual interfaces to simulate cluster nodes

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 »

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Find in Linux if your installed RAM is ECC

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 »

Convert certificate from DER to PEM format

Sometimes you get a CA certificate in DER format and some application requires it in a PEM format. OpenSSL to the rescue:

#DRBD investigate and solve a sudden Diskless issue

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 »

#Docker images cleanup

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:

CASE 2: If you want to clean up all the old images for which you no longer have any instantiated container

CASE 3: If you want… Read More »