If you are a developer, chances are you have already been asked to deploy your applications on a Kubernetes cluster. You have probably figured out this is not an easy task, especially if you don’t know Kubernetes that much. Kubernetes is a huge beast, and knowing how to define (YAML all the way) and manipulate the basic resources it offers (Pod, Deployment, Service, ConfigMap, Secret, …) is not straightforward, left alone the more advanced resources (NetworkPolicies, RBAC related ones, …).

Today there is no doubt Kubernetes is the solution of choice to run containerized applications. But, as a developer, most…

In this article we will use the VotingApp, a sample microservices application, to illustrate several of the ways an application can be deployed in a Kubernetes cluster:

• using yaml specifications
• through an Helm chart
• using Kustomize

The VotingApp

The VotingApp is an application created by Docker, it is mainly used to illustrate Docker and Kubernetes functionalities. This application follows a microservices architecture, it is made of five services as illustrated in the schema below.

In a previous article, we presented Rook and used it to set up a HA Ceph cluster. In this new article, we will install Rook on a single node K3s cluster as it’s a good way to get started with this great CNCF project.

Setup of the k3s cluster

For the purpose of this article, we will use local VM provisioned on VirtualBox using Vagrant. The Vagrantfile below defines:

• the configuration of the VM that will be created: the Linux distribution used, its IP address (192.168.33.10), the amount of RAM (2G), the addition of a disk with a capacity of 10G
• setting up K3s and…

Cilium, the eBPF-based networking solution, just released a web editor to facilitate the creation of Kubernetes network policies. In this article, we will demo the tool and use it to define a sample network policy.

A Quick Presentation of Cilium and eBPF

“Cilium is an open source project that has been designed on top of eBPF to address the networking, security, and visibility requirements of container workloads. It provides a high-level abstraction on top of eBPF.” — Cilium blog

Cilium has a wide application domain and is commonly used as a CNI plugin in Kubernetes, as illustrated in the following schema:

As not all pods can be trusted, this article will show different options to enhance process isolation through the usage of container runtimes other than the default one (runc). We will use Kubernetes k0s distribution to illustrate all of this. If you do not know k0s, you can find a quick introduction in this article.

Create a K0s Cluster

In the introduction article, we detailed the steps needed to easily setup a k0s cluster. …

This article offers a back-to-basics approach to help you understand several actions that can be done on a cluster’s nodes.

Our Test Cluster

Let’s consider a newly created kubeadm cluster containing one master and two worker nodes:

$ kubectl get nodes
NAME    STATUS   ROLES                  AGE   VERSION
k8s-1   Ready    control-plane,master   18m   v1.20.0
k8s-2   Ready    <none>                 18m   v1.20.0
k8s-3   Ready    <none>                 18m   v1.20.0

First, we will install Kubernetes Operational View (aka kube-ops-view). This application is very handy for seeing all the pods running in a cluster at a glance. There are currently 14 pods running:

• Two of them are in the default namespace and are…

The Kubernetes network proxy (aka kube-proxy) is a daemon running on each node. It basically reflects the services defined in the cluster and manages the rules to load-balance requests to a service’s backend pods.

When setting up a Kubernetes cluster, the installation of a network plugin is mandatory for the cluster to be operational. To keep things simple, the role of a network plugin is to set up the network connectivity so Pods running on different nodes in the cluster can communicate with each other. Depending upon the plugin, different network solutions can be provided: overlay (vxlan, IP-in-IP) or non-overlay.

To simplify the usage of a network plugin, Kubernetes exposes the Container Network Interface (aka CNI) so any network plugin that implements this interface can be used.

Kubernetes also allows the usage of kubenet…