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Alen Komljen

Total 43 Posts

Doing DevOps the Cloud Native Way.

  • Sarajevo
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, pipeline, drone

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, persistent storage, ceph

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

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, ...

kubernetes, persistent storage, rook

Rook: Cloud Native On-Premises Persistent Storage for Kubernetes on Kubernetes

Software-defined storage is not something new. One of the most popular is Ceph. I started with Ceph five years ago because I was looking into unified storage for OpenStack. There are many other solutions, but I like the Ceph because it is all in one solution for the block, object and file storage, and it is opensource. Inktank the company behind Ceph is later acquired by RedHat, but that made things even better. If you already have Ceph cluster running, ...

kubernetes, pipeline, jenkins

Set Up a Jenkins CI/CD Pipeline with Kubernetes

Continuous integration and delivery or CI/CD is the most crucial part of DevOps, and cloud-native too. CI/CD connects all the bits. With Kubernetes cluster deploying Jenkins server is easy. Of course thanks to Helm. The hard part is creating pipeline which builds, deploys and test your software. The focus of this post is understanding the Jenkins pipeline and what is happening in the background when running on Kubernetes. Deploy Jenkins on Kubernetes Deploying Jenkins is the easy part ...

kubernetes, troubleshooting

Learn How to Troubleshoot Applications Running on Kubernetes

I'm writing a lot of about Kubernetes for a few months already. I like the idea of cloud-native applications. There are a lot of easily installable applications for Kubernetes out there. One of the biggest resources of "Kube ready" applications is Kubeapps Hub. The list keeps growing really fast. So, all this is a good thing. But, there is also a small problem. People run some commands that they don't quite understand. It can be a copy/paste ...

kubernetes, service mesh

Kubernetes Service Mesh

A few months ago my colleague asked me what I think about integrating Linkerd to our new application running on Kubernetes. My first thought was, heck, isn't Kubernetes service and ingress enough? You can do much stuff with it. Having a service mesh seemed like overhead to me. You often have some API which is available only on the internal network. However, this is not the case anymore with modern applications. The API is probably exposed to the Internet as ...

kubernetes, ingress, nginx

Kubernetes Nginx Ingress Controller

Ingress is the built‑in Kubernetes load‑balancing framework for HTTP traffic. With Ingress, you control the routing of external traffic. When running on public clouds like AWS or GKE, the load-balancing feature is available out of the box. You don't need to define Ingress rules. In this post, I will focus on creating Kubernetes Nginx Ingress controller running on Vagrant or any other non-cloud based solution, like bare metal deployments. I deployed my test cluster on Vagrant, with kubeadm. ...

kubernetes, helm

Package Kubernetes Applications with Helm

Writing a bunch of Kubernetes configuration files is not so much fun. For a few containers, you will end up with 10+ yaml files. Maintaining them is only one issue, but running in different environments or using the same files for CI/CD is a nightmare. You can always use some bash tricks to replace some values, but that is a bad practice. Here is where Helm comes into place. I should mention that there is also another interesting tool ...

kubernetes, operators, elasticsearch

Kubernetes Elasticsearch Operator

Just after I wrote a Stateful Applications on Kubernetes post which focuses on stateful set in general, I started to look into the Kubernetes operators. An operator is a custom API object registered as Custom Resource Definition or CRD which enables you to create a custom business logic for operating with a particular service, in this case, Elasticsearch. This post will go through Elasticsearch operator in more details to show you why using an operator is probably a better idea ...

kubernetes, kube tips

Kubernetes Tips - Part 3

This post is about supported Kubernetes API versions on your cluster and services port forwarding to your localhost which can be really useful when troubleshooting or testing apps running on Kubernetes. Check other Kubernetes tips articles on my blog by using this tag kube-tips. Kubernetes API Versions If you are familiar with Kubernetes resources config files you already saw the apiVersion field at the beginning of each file. It can be confusing, because you will see a lot of different ...