Java Guild Kubernetes

Prerequisites

Following programs are necessary/handy when following this tutorial:

• kubectl
• minikube
• Lens

Objective

During the tutorial we will go over the main components of Kubernetes and demonstrate them by developing a java application.

Note: If you want to create your own docker images, then you'll need to add the following lines to your settings.xml

  <servers>
    <server>
        <id>registry.hub.docker.com</id>
        <username>USERNAME</username>
        <password>PASSWORD</password>
    </server>
  </servers>

Tutorial

Step 1: Pod

Pod

A pod is an abstraction over a container (e.g. a Docker container) and is the smallest possible unit on which actions can be performed in Kubernetes. An important aspect of pods is that they are not meant to live forever necessarily, i.e. if they are broken they are killed and a new pod is spun up. Kubernetes assigns to each pod an ip address which becomes unavailable when the pod 'dies'.

Deployment step 1

Run the following command to create a docker image with name ``:

mvn clean compile jib:build

Verify you are connected to the kubernetes cluster you intend to use with

kubectl config current-context

Apply the deployment file:

kubectl apply -f ./pod/deployment/deployment.yml

If wanted, you can now change the number of replicas (which would create additional pods).

Once you are done, you can delete the deployment:

kubectl delete -f ./pod/deployment/deployment.yml