PodSet Operator in Java Using Fabric8 Kubernetes Client

Note

This project is a demo project for blog for writing a simple Kubernetes operation in Java using Fabric8 Kubernetes Client. You can find full blog here: Writing a simple Kubernetes Operation in Java

This is a demo operator which implements a simple operator for a custom resource called PodSet which is somewhat equal to ReplicaSet. Here is what this resource looks like:

apiVersion: demo.fabric8.io/v1alpha1
kind: PodSet
metadata:
  name: example-podset
spec:
  replicas: 5

Each PodSet object would have 'x' number of replicas, so this operator just tries to maintain x number of replicas checking whether that number of pods are running in cluster or not.

How to Build

   mvn clean install

How to Run

   mvn exec:java -Dexec.mainClass=io.fabric8.podset.operator.PodSetOperatorMain

Make Sure that PodSet Custom Resource Definition is already applied onto the cluster. If not, just apply it using this command:

kubectl apply -f src/main/resources/crd.yaml

Once everything is set, you can see that operator creating pods in your cluster for PodSet resource:

Deploying onto Kubernetes(minikube) using Eclipse JKube

• Make Sure that PodSet Custom Resource Definition is already applied onto the cluster. If not, just apply it using this command:

kubectl apply -f src/main/resources/crd.yaml

• Make sure that you have given correct privileges to ServiceAccount that would be used by the Pod, it's default in our case. Otherwise you might get 403 from Kubernetes API server.

kubectl create clusterrolebinding default-pod --clusterrole cluster-admin --serviceaccount=default:default

# In case of some other namespace:
kubectl create clusterrolebinding default-pod --clusterrole cluster-admin --serviceaccount=<namespace>:default

• Build Docker Image

mvn k8s:build

• Generate Kubernetes Manifests

mvn k8s:resource

• Apply generated Kubernetes Manifests onto Kubernetes

mvn k8s:apply

Once generated resources are applied, try creating one of PodSet objects in src/main/resources

kubectl apply -f src/main/resources/cr.yaml