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 »
As I discussed in post Portable #Docker #Swarm made of #RaspberryPI – Updated hardware there were several hardware updates done to the swarm. One of the updates was adding a switch and connecting all the Raspberry PIs to the switch. First version of the Docker Swarm was done using the wifi connections of the PIs.… Read More »
I wanted to update my hardware setup for the Docker Swarm cluster from post Portable #Docker #Swarm made of #RaspberryPI. The idea was to make it more portable, more reliable and a bit faster. The following steps were done: Add ethernet support The original setup used a small Edimax router with the Raspberry Pi nodes… Read More »
Nginx can be used very nicely to aggregate resources after the same fronted by using it as a proxy. I want my set-up to be like: URL1: https://blog.voina.uk -> nas1 hosted wordpress URL2: https://blog.voina.uk/store -> nas2 hosted store with URL https://nas/store URL3: https://blog.voina.uk/doc -> nas4 hosted wiki with URL https://nas4/wiki How can we do this… Read More »
In a DRBD setup as described in #DRBD based disk replication of a production cluster to a remote site cluster on RHEL 6 there is a special case when due to some external issues the communication line between the sites is down due to technical reason for a longer period of time (days). The line… Read More »