Hazelcast with Istio Service Mesh

Use Hazelcast in an Istio environment.

In this tutorial, you’ll learn how to set up a Hazelcast cluster and connect it with Hazelcast client. Then, you will also see how to deploy an application with embedded Hazelcast.

Before you Begin

You need the following:

A Kubernetes cluster

This tutorial uses Google Kubernetes Engine but you can use any Kubernetes cluster.
```
gcloud container clusters create hazelcast-cluster --num-nodes=4
```

Install Istio 1.7.3

This code sample has been tested against Istio 1.7.3

Download Istio and configure the path for istioctl.

curl -L https://istio.io/downloadIstio | sh -
export PATH=`pwd`/`ls | grep istio`/bin:$PATH

Install Istio CRDs.

istioctl install --set profile=demo --skip-confirmation

Make sure that both the istioctl client and the control plane have the same version.
```
istioctl version
```

client version: 1.7.3
control plane version: 1.7.3
data plane version: 1.7.3 (2 proxies)

Run the Code Sample

Clone this repository and apply RBAC. RBAC is needed by the hazelcast-kubernetes plugin discovery.

git clone https://github.com/hazelcast-guides/istio.git
cd istio
kubectl apply -f rbac.yaml

Istio Sidecar AutoInjection is done automatically if you label the default namespace with istio-injection. If you want to implement manual injection with the deployments then you need to use istioctl kube-inject.

kubectl label namespace default istio-injection=enabled

The business logic in both examples are the same to keep it simple. put operation puts a key-value pair to Hazelcast and get operation returns the value together with the Kubernetes Pod name. PodName is used to show that the value is returned from any Pod inside the Kubernetes cluster to prove the true nature of distributed cache.

Hazelcast Client Server

Let’s first switch to the client-server directory.

cd hazelcast-client-server

Client-Server code sample can be built and pushed to your own Docker Hub or some other registry via following command but that is optional.

mvn compile com.google.cloud.tools:jib-maven-plugin:1.8.0:build -Dimage=YOUR-NAME/istio-client:1.0

Instead, you can use the already pre-built docker image hazelcastguides/istio-client:1.0.

If you want to build your own image, then do not forget to update hazelcast-client.yaml with your own image.

Deploy Hazelcast Cluster:

kubectl apply -f hazelcast-cluster.yaml

You can see that 3 member cluster has been initiated with 3 pods. 2/2 in READY column means that there are 2 containers running in each Pod. One is Hazelcast member and the other is Envoy Proxy.

$ kubectl get pods
NAME                  READY   STATUS    RESTARTS   AGE
hazelcast-cluster-0   2/2     Running   0          60s
hazelcast-cluster-1   2/2     Running   0          44s
hazelcast-cluster-2   2/2     Running   0          27s

Deploy the Spring Boot application with the Hazelcast client:

kubectl apply -f hazelcast-client.yaml

Check the logs and see that the Spring Boot service is connected to the cluster:

$ kubectl logs hazelcast-client-0 hazelcast-client
...
Members [3] {
	Member [10.16.2.14]:5701 - 51274b4d-dc7f-4647-9ceb-c32bfc922c95
	Member [10.16.1.15]:5701 - 465cfefa-9b26-472d-a204-addf3b82d40a
	Member [10.16.2.15]:5701 - 67fdf27a-e7b7-4ed7-adf1-c00f785d2325
}
...

Run a container with cURL installed and set an environment variable to point to the Spring load balancer.

First, find the IP of Spring Boot Service:

$ kubectl get svc springboot-service
NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
springboot-service   ClusterIP   10.19.250.127   <none>        80/TCP    3m29s

Launch a curl container inside Kubernetes cluster and set the service IP as an environment variable:

kubectl run curl --rm --image=radial/busyboxplus:curl -i --tty
SPRINGBOOT_SERVICE=10.19.250.127

Put a value to the cluster:

$ curl "${SPRINGBOOT_SERVICE}/put?key=1&value=2"
{"value":"2","podName":"hazelcast-client-2"}

Get the value from cluster in a loop and see that it is retrieved from different Pod names:

$ while true; do curl "${SPRINGBOOT_SERVICE}/get?key=1"; sleep 2;echo; done
{"value":"2","podName":"hazelcast-client-1"}
{"value":"2","podName":"hazelcast-client-0"}
...

In this sample, you were able to deploy a Spring Boot based microservice with Hazelcast client-server topology in Istio Environment.

Clean up the deployments with the following commands:

kubectl delete -f hazelcast-client.yaml
kubectl delete -f hazelcast-cluster.yaml

Hazelcast Embedded

Switch to the embedded code sample directory:

cd hazelcast-embedded

Embedded code sample can be built and pushed to your own Docker Hub or some other registry via following command but that is optional:

mvn compile com.google.cloud.tools:jib-maven-plugin:1.8.0:build -Dimage=YOUR-NAME/istio-embedded:1.0

Instead, you can use the already pre-built docker image hazelcastguides/istio-embedded:1.0.

If you want to build your own image, then do not forget to update hazelcast-embedded.yaml with your own image.

Deploy Hazelcast Embedded Sample:

$ kubectl apply -f hazelcast-embedded.yaml
statefulset.apps/hazelcast-embedded created
service/hazelcast-embedded-headless created
service/springboot-service created

You can check that the application started and Hazelcast successfully formed a cluster.

$ kubectl logs pod/hazelcast-embedded-0 hazelcast-embedded
...
Members {size:3, ver:3} [
        Member [10.12.1.6]:5701 - 644e6bbf-335a-410b-80ab-0cb648dbc772
        Member [10.12.2.8]:5701 - 0ab13148-b6bb-477e-970b-0b5c226ed2aa this
        Member [10.12.3.4]:5701 - 72f56c90-f55e-490c-b3c0-d40fe970557f
]
...

When you list the services used, you will see that you have two Kubernetes Services: hazelcast-embedded-headless and springboot-service. hazelcast-embedded-headless is used to handle Hazelcast cluster discovery operation so it has no need to have an IP address. springboot-service is the loadbalancer that is used to receive http requests and forward them to one of the underlying pods to respond.

$ kubectl get svc
NAME                          TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
hazelcast-embedded-headless   ClusterIP   None           <none>        5701/TCP   9s
kubernetes                    ClusterIP   10.19.240.1    <none>        443/TCP    73m
springboot-service            ClusterIP   10.19.252.76   <none>        80/TCP     9s

Let’s now put a key-value pair into Hazelcast cluster through Spring Boot REST Service and then call get operation in a loop to see the value is returned from different Pods.

Firstly, let’s run a container with curl installed and set an environment variable to point to Spring Load Balancer:

kubectl run curl --rm --image=radial/busyboxplus:curl -i --tty
SPRINGBOOT_SERVICE=10.19.252.76

Put a value to the cluster:

$ curl "${SPRINGBOOT_SERVICE}/put?key=1&value=2"
{"value":"2","podName":"hazelcast-embedded-2"}

Get the value from cluster in a loop and see that it is retrieved from different Pod names:

$ while true; do curl "${SPRINGBOOT_SERVICE}/get?key=1"; sleep 2;echo; done
{"value":"2","podName":"hazelcast-embedded-1"}
{"value":"2","podName":"hazelcast-embedded-0"}
...

In this sample, you were able to deploy a Spring Boot based microservice with Hazelcast Embedded in Istio Environment. Let’s clean up the deployments with the following command.

kubectl delete -f hazelcast-embedded.yaml

Summary

This tutorial demonstrates how to use Hazelcast Embedded and client/server topology in an mTLS-enabled Istio environment with Automatic Sidecar Injection. Hazelcast continuously tries to support cloud native technologies and verifies those environments as they evolve.