Kubernetes

Kubernetes simplified applications management a lot and this also applies to databases like MySQL/MariaDB, but lot of DevOps forget to apply traditional maintenance and optimization which is still necessary unless you are using some operator capable of doing so. The optimization method that will be described here applies just to single and master-slave replicated MySQL/MariaDB instances. If you run some clustered version like Galera , you probably have to find another way because of possible consistence and performance problems during the eventual optimization. This method would still work but you may have unpredictable consequences. ...

In the Cloud era topics like backup became kind of less important. One of the reasons is probably possibility to take automated snapshots of your volumes, another maybe that you can use some kind of redundancy. However, there are still use cases where you need more traditional ways to backup your data. In this article we will discuss about syncing files from your Kubernetes volume to S3 compatible storage. If you know the concept of Persistent Volumes in Kubernetes, then you also know three of the supported access modes: ReadWriteOnce, ReadOnlyMany or ReadWriteMany. The first mode allows a volume to be mounted just once, meaning it is usually already used by some pod and it is possible to access it just through this pod. The other two types can be mounted multiple times, meaning multiple pods can access the same data. In case of ReadOnlyMany all pods can just read the data, but in case of ReadWriteMany all pods can read and write data. In this article we are going to focus to these volumes that we can mount multiple times. ...

Do you develop or plan to develop a Kubernetes native application in Golang, controller or operator? Such application strongly depends on being inside Kubernetes and development outside of Kubernetes may be a real hassle. Usually you have to build an image over and over again and restart the pod (with imagePullPolicy set to Always). This is very boring and time consuming procedure. Two years ago I developed an image to auto-recompile and auto-restart Go application, named go-reflex , but it was intented to be used by docker-compose. Today I gave it a try with Kubernetes, namely with kind (Kubernetes in Docker) and it turned out it works like a charm. In this article I will describe how to set this up and save your time for something creative (i.e. beer drinking). ...

You may wonder what the heck is helmfile ? Well, I would say what is docker-compose to Docker, this is helmfile to Helm . Basically, it allows us to install the whole stack of applications to our Kubernetes cluster in a declarative way. And you may also wonder why is cert-manager so special? I would say cert-manager itself is not that special Helm chart, but it contains CRD ’s which may be installed either by using value installCRDs=true or by installing them using kubectl apply before you install the chart. ...

Do you need ReadWriteMany storage class and your cloud provider doesn’t offer it? According to Wikipedia , Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems (Sun) in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed. Even though this idea is 35 years old, it is still very useful in your Kubernetes cluster, specially if you need ReadWriteMany storage class. If you are interrested about this, you are probably wondering how to achieve this? ...

How to deploy new Docker images to your Kubernetes cluster? Of course, there are many ways and one of the most common ways is to use kubectl set image, for example: 1 kubectl set image deployment/nginx-deployment nginx=nginx:1.17.5-alpine However, what happens if you have more containers in your deployment pod spec? And what if you also have initContainers? Fortunately, kubectl patch can help. Let’s assume we have two containers and one init container. Here is the patch file (patch.yaml) we can use: ...

Few months ago I wrote an article about replacing Minikube with MicroK8s , but now we have even better soluion, kind . Like dind allows running Docker inside Docker containers, kind allows running Kubernetes inside Docker containers. kind basically abstracts nodes as Docker containers and then runs Kubernetes inside. After you install Golang , it is quite easy to install and setup kind: 1 2 GO111MODULE="on" go get sigs.k8s.io/kind@v0.5.1 kind create cluster After some 30 seconds your single node cluster will be ready for development and testing. But that’s not all, kind allows much complex setup, for example three node cluster with one master and two workers. Let’s first create declarative object: ...

DigitalOcean just got competition from Scaleway with their managed Kubernetes service, Kapsule.

Running self managed Kubernetes cluster is not that difficult at the end.

MicroK8s is a lightweight version of Kubernetes for local development. It can run on Linux (natively) or Mac (in a light VM ).