javascript-example-operator

{ConfigMap|CRD}-based approach for managing X in Kubernetes and OpenShift.

This operator uses abstract-operator library.

Info

This project demonstrates the the JavaScript way to write the operators for K8s and OpenShift. It uses the Nashorn JavaScript Engine in JDK. However, it requires also quite a lot of Java dependencies on the classpath, so that for the sake of simplicity, we prepared a simple demo where it builds the existing Java operator and creates an uber jar that is used as a simple form of passing all the needed dependencies. The handlers for the events (key parts) are implemented in JavaScript.

example.js:

load("common.js")

// on add handler
var onAdd = function(foo) {
  print("Hello from JavaScript, added " + foo.name);
};

// on delete handler
var onDelete = function(foo) {
  print("Hello from JavaScript, deleted " + foo.name);
};

// start the operator
startOperator(onAdd, onDelete);

// sleep 10 years
java.lang.Thread.sleep(1000 * 60 * 60 * 24 * 365 * 10);

common.js:

function startOperator(onAdd, onDelete) {
    var DefaultKubernetesClient = Java.type("io.fabric8.kubernetes.client.DefaultKubernetesClient");
    var client = new DefaultKubernetesClient();

    var AbstractOperator = Java.type("io.radanalytics.operator.common.AbstractOperator");
    var MyOperator = Java.extend(AbstractOperator, { onAdd: onAdd, onDelete: onDelete });
    var op = new MyOperator();
    op.infoClass = Java.type("io.radanalytics.types.SparkCluster").class;
    op.namespace = "myproject"
    op.prefix = "radanalytics.io"
    op.client = client;
    op.isOpenshift = true;
    op.fullReconciliationRun = true;
    var future = op.start();
    return future;
}

Usage

make devel-kubernetes # for K8s

make devel # for OpenShift

or even without deploying to K8s:

jrunscript -cp ./spark-operator-*.jar -f example.js

Demo

kubectl apply -f ./manifest/operator.yaml
kubectl apply -f ./examples/cluster.yaml

meanwhile in the Kubernetes logs:

...
2018-12-04 14:53:31 INFO  AbstractOperator:419 - creating sparkcluster:  
my-spark-cluster
Hello from JavaScript, added my-spark-cluster
...

Notice that Hello from JavaScript.. was declared above in the JavaScript code in the onAdd() method.

Notes

Since we call the start() method on the operator directly, it lacks the periodical full-reconciliation logic that is normally scheduled in the Entrypoint.java.