Alen Komljen

Hi, I'm Alen Komljen and I write this blog. I help companies to embrace DevOps and Cloud Native.

kubernetes, prometheus, monitoring

Get Kubernetes Cluster Metrics with Prometheus in 5 Minutes

Having a Kubernetes cluster up and running is pretty easy these days. But, when you start to use the cluster and deploy some applications you might expect some issues over time. Kubernetes being a distributed system is not easy to troubleshoot. You need a good monitoring solution and because the Prometheus is CNCF project as Kubernetes it is probably the best fit. In this post, I will show you how to get the Prometheus running and start monitoring your Kubernetes ...

kubernetes, persistent storage

Kubernetes Persistent Volumes with Deployment and StatefulSet

I get a lot of questions about Kubernetes and persistence. Of course, persistence is important for stateful apps. We often say that for stateful apps you need to use StatefulSet and for stateless apps Deployment. This doesn't mean that you couldn't use deployment to define stateful apps with persistent volumes. For example, the official MySQL Helm chart is using deployment. So, it can be done, but users get confused about this. What is the deal? When should you use deployment ...

monthly update

Monthly Update 1

It is impossible for me to try every piece of technology that comes out and to write about it. I had this idea for a while and decided to start writing monthly updates. Each update will have a few topics that I found interesting. Sometimes there will be things that I was working on, some exciting news, tools that are interesting and related to above. Feel free to send suggestions or to comment on something. Let me know if you ...

kubernetes, drone, ci/cd, pipeline

Set Up a Drone CI/CD Pipeline with Kubernetes

I like to say that continuous delivery or CD is the most important part of Cloud Native. There are so much great tools out there and you need to pick up the right ones. A few weeks ago I was writing almost about the same topic, only with Jenkins. While the Jenkins is the most used CI/CD tool, not every team is happy with it. Jenkins has a huge number of plugins and the great set of features, but ...

kubernetes, ceph, persistent storage

Using Existing Ceph Cluster for Kubernetes Persistent Storage

I wrote about Rook storage a few weeks ago, but maybe you already have Ceph cluster running in your datacenter. Or you prefer to use Ceph on separate nodes and without Kubernetes. Also, currently Rook is alpha software and not ready for production use. I would assume that this large Ceph cluster if you have one, is also used for other services outside Kubernetes. Whatever is the case it is simple to connect Ceph and Kubernetes together to provision persistent ...

kubernetes, persistent storage, resize

Easy Way to Resize Kuberntes Persistent Volumes

The previous post about Rook got great attention from the community. But, I also got a lot of questions about persistence on Kubernetes in general. Among many questions, there were a few about resizing persistent volume claims or PVCs. If you are using on-premises storage solutions like Ceph (Rook) this is not the big issue. The part of the reason is that when you create a volume in Ceph, let's say a 100GB, this space is not actually allocated. But, ...