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: # openssl x509 -inform der -in myCA.der -out myCA.pem
Category Archives: DataCenter
#DRBD Growing online a replicated resource in a complex enterprise environment
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 »
#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: 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 »
Portable #RaspberryPI #Docker #Swarm – Static IP, Ethernet based, #Portainer
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 »
Portable #Docker #Swarm made of #RaspberryPI – Updated hardware
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 proxy_pass an URI to another server with a different URI
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.org -> nas1 hosted wordpress URL2: https://blog.voina.org/store -> nas2 hosted store with URL https://nas/store URL3: https://blog.voina.org/doc -> nas4 hosted wiki with URL https://nas4/wiki How can we do this… Read More »
#DRBD: Synchronization of sites after the connection between sites is down for a long time
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 »
Portable #Docker #Swarm made of #RaspberryPI
This is the new cool thing to build at home. A small cluster made of Raspberry PIs. Hardware setup of the cluster ITEM 1: Raspberry Pi 3 Model B I went for a set of 5 PIs because of the greater flexibility when you get more machines. I hope to be able to test several… Read More »
#Docker volumes and Selinux
When running complex environments on Docker on Linux again we face the mighty selinux. There are plenty of selinux alerts generated when I start my environment when the host machines have selinux enabled and volumes are used by the containers. Setting selinux permissions is hard and tedious and many people just prefer to disable it.… Read More »