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Hazelcast embedded on Kubernetes

This is a sample Spring Boot application with embedded Hazelcast, which presents forming a Hazelcast cluster on Kubernetes.

This sample uses Kubernetes API for Hazelcast member discovery.

1. Configure Hazelcast to work on Kubernetes

You can configure Hazelcast to work on Kubernetes using the hazelcast-kubernetes plugin.

Add the following Maven dependencies:


Then, configure the Kubernetes Discovery Strategy. You can do it in two different manners: Java-based configuration or XML configuration. In this code sample, we used the first approach:

public Config hazelcastConfig() {
    Config config = new Config();
    JoinConfig joinConfig = config.getNetworkConfig().getJoin();
    return config;

The equivalent XML configuration would look as follows:

<?xml version="1.0" encoding="UTF-8"?>
<hazelcast xmlns="http://www.hazelcast.com/schema/config" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.hazelcast.com/schema/config hazelcast-config-3.11.xsd">
      <multicast enabled="false"/>
      <kubernetes enabled="true"/>

Note that this configuration will form a Hazelcast with all Hazelcast instances assigned to services in the current namespace. If you want to filter the instances, use the properties as described here.

2. Build application and Docker image

The following command compiles the project, builds the Docker image, and pushes it into your Docker Hub account.

mvn clean compile jib:build -Dimage=leszko/hazelcast-kubernetes-embedded-sample

Please change leszko to your Docker Hub login. Then, make sure that your image in Docker Hub is public (you can do it on the Docker Hub website).

3. Grant access to Kubernetes API

In order for the POD to use Kubernetes API, you need to create the given Role Binding.

kubectl apply -f rbac.yaml

4. Deploy application

Update deployment.yaml with the image you pushed to Docker Hub. Then, to deploy an application, run the following command:

kubectl apply -f deployment.yaml

5. Verify that Application works correctly

You can check that the Deployment and Service were created.

$ kubectl get all
NAME                                      READY     STATUS    RESTARTS   AGE
pod/hazelcast-embedded-57f84c545b-64tnk   1/1       Running   0          2m
pod/hazelcast-embedded-57f84c545b-jjhcs   1/1       Running   0          45s

NAME                         TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)                         AGE
service/hazelcast-embedded   LoadBalancer   5701:32302/TCP,8080:31613/TCP   2m

NAME                                       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.extensions/hazelcast-embedded   2         2         2            2           2m

NAME                                                  DESIRED   CURRENT   READY     AGE
replicaset.extensions/hazelcast-embedded-57f84c545b   2         2         2         2m

NAME                                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/hazelcast-embedded   2         2         2            2           2m

NAME                                            DESIRED   CURRENT   READY     AGE
replicaset.apps/hazelcast-embedded-57f84c545b   2         2         2         2m

In the logs for PODs, you should see that the Hazelcast members formed a cluster.

$ kubectl logs pod/hazelcast-embedded-57f84c545b-jjhcs
 Members {size:2, ver:4} [
         Member []:5701 - 33076b61-e99d-46f2-b5c1-35e0e75f2311
         Member []:5701 - 9ba9bb61-6e34-460a-9208-c5a644490107 this

Then, you can access the application, by its EXTERNAL-IP.

Verify Application

Verify Application