Skip to main content

Embedded OrientDB on a OpenShift / Kubernetes cluster

A few tips on setting up an embedded OrientDB to run on OpenShift / Kubernetes cluster.

  • Set the ORIENTDB_NODE_NAME system property or environment variable. If your database volumes are host volumes, you can use the downwards API spec.nodeName. If the node name contains dots, replace those with dashes for example. If you use something like OpenShift persistence volumes, make sure that the running pods ORIENTDB_NODE_NAME matches with the node name values it reads from the DB.
  • Use at least 3 replicas and don't use even number due to split-brain clustering issues
  • If you use rolling upgrade strategy, give the pods some time to start up the DBs so no more than one pod is unavailable at a time. This way syncing up the cluster status becomes smoother.
  • Use the newNodeStrategy dynamic OrientDb distribution configuration parameter so unreachable nodes don't break up the write quorum so easily.
  • Use Hazelcast to discover the cluster members. There is a library for that. If that does not work you might need to do a custom implementation using the Openshift / Kubernetes REST API and node labels to find all the members. This means calling the API from the container with a custom Hazelcast resolver
  • If possible, create a liveness probe which checks if you can query a database. Avoid using writes since there is the danger of killing all pods due to unreachable quorum if multiple pods are down simultaneously.
Labels:

Comments

Post a Comment

Popular posts from this blog

I'm not a passionate developer

A family friend of mine is an airlane pilot. A dream job for most, right? As a child, I certainly thought so. Now that I can have grown-up talks with him, I have discovered a more accurate description of his profession. He says that the truth about the job is that it is boring. To me, that is not that surprising. Airplanes are cool and all, but when you are in the middle of the Atlantic sitting next to the colleague you have been talking to past five years, how stimulating can that be? When he says the job is boring, it is not a bad kind of boring. It is a very specific boring. The "boring" you would want as a passenger. Uneventful.  Yet, he loves his job. According to him, an experienced pilot is most pleased when each and every tiny thing in the flight plan - goes according to plan. Passengers in the cabin of an expert pilot sit in the comfort of not even noticing who is flying. As someone employed in a field where being boring is not exactly in high demand, this sounds pro...
Post a Comment
Read more

Bird is causing high CPU on my macOS

There is no lack of people complaining about MacOS Tahoe, mostly about rounded corners and inconsistent design decisions. I have not paid that much attentention to that, but there is one mac bug i have paid attention to. It hasn't been a visual or ux but rather few system processes pegging the CPU. trustd , alongside with ecosystemd and ecosystemanalyticsd all reported high CPU usage. I can't exactly recall when this started, it might have predated my Tahoe upgrade but anyway, the trio of processes all had high CPU usage. Sure, it may have been the virtual efficiency cores and whether it affeced battery life or slowed down other processes i don't know to be hon...
Post a Comment
Read more

Ousterhout's law

Back in the day, everyone was using Winamp. It is a music player with the user interface of a mixing console. The bloody thing had an equalizer on the front page! As an amateur music producer, I know that EQ is a powerful tool but making changes that sound good is difficult, to say the least. Mixing engineers spend considerable effort with the artist to balance the frequency ranges to arrive at the desired musical outcome. I bet the 15-year-old me butchered a lot of songs with the thing. Now we are using Spotify, a player with basically a search bar and a play button. I ran into something called Ousterhout's Law on the  Operating Systems: Three Easy Pieces book . Here is a quote from the book TIP: AVOID VOO-DOO CONSTANTS (OUSTERHOUT’S LAW) Avoiding voo-doo constants is a good idea whenever possible. Unfortunately, as in the example above, it is often difficult. One could try to make the system learn a good value, but that too is not straightforward. The frequent result: a configura...
Post a Comment
Read more