Connect to Hazelcast from outside Kubernetes

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Learn how to connect to a Hazelcast cluster running in Kubernetes from outside of the Kubernetes environment.

Overview

In this tutorial, we’ll look at two available options for the Expose Externally feature of Hazelcast Platform Operator:

  • Unisocket - client requests are load balanced between Hazelcast members

  • Smart - the client connects to all members and sends requests directly to the members owning the data

The tutorial should take approximately 5 to 10 minutes to complete.

Prerequisites

Before you begin, make sure that you have:

Starting with version 5.13, Hazelcast Platform Operator only supports Hazelcast Enterprise cluster creation. Even when the feature is used in Hazelcast Open Source clusters, Hazelcast Platform Operator requires a license key to run a cluster.
This tutorial uses LoadBalancer services to connect to Hazelcast from outside of the Kubernetes cluster. Therefore, it is essential to ensure that your Kubernetes cluster can assign public IPs to LoadBalancer services. This is particularly important if you are using a local Kubernetes cluster such as Minikube or Kind.

Unisocket

The first option is to use the Unisocket type. This option uses the standard Kubernetes mechanism that automatically load balances the traffic to Hazelcast members.

Start the Hazelcast cluster

Create the Hazelcast cluster with the Expose Externally feature enabled using Unisocket type:

kubectl apply -f - <<EOF
apiVersion: hazelcast.com/v1alpha1
kind: Hazelcast
metadata:
  name: my-hazelcast-unisocket
spec:
  licenseKeySecretName: hazelcast-license-key
  exposeExternally:
    type: Unisocket
    discoveryServiceType: LoadBalancer
EOF

For discoveryServiceType you can use:

  • LoadBalancer - will create an external LoadBalancer for discovery service;

  • NodePort - will expose the discovery service via NodePort.

Verify the Hazelcast cluster

Check the cluster status by running the following command.

$ kubectl get hazelcast my-hazelcast-unisocket
NAME           STATUS    MEMBERS
my-hazelcast   Running   3/3

After verifying that the cluster is Running and all the members are ready (3/3), find the discovery address:

$ kubectl get hazelcastendpoint my-hazelcast-unisocket
NAME                     TYPE        ADDRESS
my-hazelcast-unisocket   Discovery   34.135.7.75:5701

The ADDRESS column displays the external address of your Hazelcast cluster.

Connect Hazelcast Clients to the cluster

  1. Open the examples folder to access all sample clients:

    cd hazelcast-platform-operator-expose-externally

    The sample code (excluding CLC) for this tutorial is in the docs/modules/ROOT/examples/operator-expose-externally directory.

  2. Configure the Hazelcast client with the external address and disable smart routing to use the unisocket connection.

  • CLC

  • Java

  • NodeJS

  • Go

  • Python

  • .NET

CLC must be installed in your system. See the CLC installation instructions.

Add the cluster config to the CLC:

clc config add hz cluster.name=dev cluster.address=<EXTERNAL-IP>
package com.hazelcast;

import com.hazelcast.client.HazelcastClient;
import com.hazelcast.client.config.ClientConfig;
import com.hazelcast.client.properties.ClientProperty;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.map.IMap;

import java.util.Random;

public class Main {
    public static void main(String[] args) throws Exception {
        ClientConfig config = new ClientConfig();
        config.getNetworkConfig().addAddress("<EXTERNAL-IP>");
        config.getProperties().setProperty(ClientProperty.DISCOVERY_SPI_PUBLIC_IP_ENABLED.toString(), "true");
        HazelcastInstance client = HazelcastClient.newHazelcastClient(config);

        System.out.println("Successful connection!");
        System.out.println("Starting to fill the map with random entries.");

        IMap<String, String> map = client.getMap("map");
        Random random = new Random();
        while (true) {
            int randomKey = random.nextInt(100_000);
            map.put("key-" + randomKey, "value-" + randomKey);
            System.out.println("Current map size: " + map.size());
        }
    }
}
'use strict';

const { Client } = require('hazelcast-client');

const clientConfig = {
    network: {
        clusterMembers: [
            '<EXTERNAL-IP>'
        ]
    },
    properties: {
        ['hazelcast.discovery.public.ip.enabled']: true
    }
};

(async () => {
    try {
        const client = await Client.newHazelcastClient(clientConfig);
        const map = await client.getMap('map');
        await map.put('key', 'value');
        const res = await map.get('key');
        if (res !== 'value') {
            throw new Error('Connection failed, check your configuration.');
        }
        console.log('Successful connection!');
        console.log('Starting to fill the map with random entries.');
        while (true) {
            const randomKey = Math.floor(Math.random() * 100000);
            await map.put('key' + randomKey, 'value' + randomKey);
            const size = await map.size();
            console.log(`Current map size: ${size}`);
        }
    } catch (err) {
        console.error('Error occurred:', err);
    }
})();
package main

import (
	"context"
	"fmt"
	"math/rand"

	"github.com/hazelcast/hazelcast-go-client"
)

func main() {
	config := hazelcast.Config{}
	cc := &config.Cluster
	cc.Network.SetAddresses("<EXTERNAL-IP>")
	cc.Discovery.UsePublicIP = true
	ctx := context.TODO()
	client, err := hazelcast.StartNewClientWithConfig(ctx, config)
	if err != nil {
		panic(err)
	}
	fmt.Println("Successful connection!")
	fmt.Println("Starting to fill the map with random entries.")
	m, err := client.GetMap(ctx, "map")
	if err != nil {
		panic(err)
	}
	for {
		num := rand.Intn(100_000)
		key := fmt.Sprintf("key-%d", num)
		value := fmt.Sprintf("value-%d", num)
		if _, err = m.Put(ctx, key, value); err != nil {
			fmt.Println("ERR:", err.Error())
		} else {
			if mapSize, err := m.Size(ctx); err != nil {
				fmt.Println("ERR:", err.Error())
			} else {
				fmt.Println("Current map size:", mapSize)
			}
		}
	}
}
import logging
import random

import hazelcast

logging.basicConfig(level=logging.INFO)

client = hazelcast.HazelcastClient(
    cluster_members=["<EXTERNAL-IP>"],
    use_public_ip=True,
)

print("Successful connection!", flush=True)
print("Starting to fill the map with random entries.", flush=True)

m = client.get_map("map").blocking()

while True:
    random_number = str(random.randrange(0, 100000))
    m.put("key-" + random_number, "value-" + random_number)
    print("Current map size:", m.size())
using Hazelcast;
using Microsoft.Extensions.Logging;


class CsharpExample
{
    static async Task Main(string[] args)
    {

        var options = new HazelcastOptionsBuilder()
            .With(args)
            .With((configuration, options) =>
            {
                options.LoggerFactory.Creator = () => LoggerFactory.Create(loggingBuilder => loggingBuilder.AddConfiguration(configuration.GetSection("logging")).AddConsole());
                options.Networking.Addresses.Add("<EXTERNAL-IP>");
                options.Networking.SmartRouting = false;
            })
            .Build();
        var client = await HazelcastClientFactory.StartNewClientAsync(options);


        Console.WriteLine("Successful connection!");
        Console.WriteLine("Starting to fill the map with random entries.");

        var map = await client.GetMapAsync<string, string>("map");
        var random = new Random();
        while (true)
        {
            var randomKey = random.Next(100_000);
            await map.PutAsync("key-" + randomKey, "value-" + randomKey);
            Console.WriteLine("Current map size: " + await map.GetSizeAsync());
        }
    }
}

Now you can start the application.

  • CLC

  • Java

  • NodeJS

  • Go

  • Python

  • .NET

Fill a map:

for i in {1..10};
do
   clc -c hz map set --name map1 key-$i value-$i;
done

Check the map size:

clc -c hz map size --name map1
cd java-unisocket
mvn package
java -jar target/*jar-with-dependencies*.jar

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd nodejs-unisocket
npm install
npm start

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd go-unisocket
go run main.go

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd python-unisocket
pip install -r requirements.txt
python main.py

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd dotnet-unisocket
dotnet build
dotnet run

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....

Smart Client

The second option is to use the Smart type. With this option, each Hazelcast member is exposed with its own service (it can be either LoadBalancer or NodePort). Hazelcast smart client is capable of mapping the given key with its owner member, which means that it sends the data directly to the member which contains the right data partition.

Start the Hazelcast cluster

Create the Hazelcast cluster with the Expose Externally feature enabled using Smart type:

kubectl apply -f - <<EOF
apiVersion: hazelcast.com/v1alpha1
kind: Hazelcast
metadata:
  name: my-hazelcast-smart
spec:
  licenseKeySecretName: hazelcast-license-key
  exposeExternally:
    type: Smart
    discoveryServiceType: LoadBalancer
    memberAccess: LoadBalancer
EOF

This creates the Hazelcast cluster and one LoadBalancer service for discovery and one LoadBalancer service for each pod.

For discoveryServiceType you can use:

  • LoadBalancer - creates an external LoadBalancer for discovery service;

  • NodePort - exposes the discovery service via NodePort.

For memberAccess you can use the following options:

  • LoadBalancer - lets the client access Hazelcast member with the LoadBalancer service;

  • NodePortNodeName - lets the client access Hazelcast member with the NodePort service and the node name;

  • NodePortExternalIP - lets the client access Hazelcast member with the NodePort service and the node external IP/hostname

Verify the Hazelcast cluster

Check the cluster status by running the following command:

$ kubectl get hazelcast my-hazelcast-smart
NAME           STATUS    MEMBERS
my-hazelcast   Running   3/3

After verifying that the cluster is Running and all the members are ready (3/3), find the discovery and member addresses:

$ kubectl get hazelcastendpoint --selector="app.kubernetes.io/instance=my-hazelcast-smart"
NAME               TYPE        ADDRESS
my-hazelcast       Discovery   35.184.21.18:5701
my-hazelcast-0     Member      34.121.197.134:5701
my-hazelcast-1     Member      35.238.20.134:5701
my-hazelcast-2     Member      34.30.60.128:5701
my-hazelcast-wan   WAN         35.184.21.18:5701

The ADDRESS column displays the external addresses of your Hazelcast cluster and members.

Connect Hazelcast clients to the cluster

Configure the Hazelcast client to connect to the cluster external address.

  • CLC

  • Java

  • NodeJS

  • Go

  • Python

  • .Net

CLC must be installed in your system. See the CLC installation instructions.

Add the cluster config to the CLC:

clc config add hz cluster.name=dev cluster.address=<EXTERNAL-IP>
package com.hazelcast;

import com.hazelcast.client.HazelcastClient;
import com.hazelcast.client.config.ClientConfig;
import com.hazelcast.client.properties.ClientProperty;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.map.IMap;

import java.util.Random;

public class Main {
    public static void main(String[] args) throws Exception {
        ClientConfig config = new ClientConfig();
        config.getNetworkConfig().addAddress("<EXTERNAL-IP>");
        config.getProperties().setProperty(ClientProperty.DISCOVERY_SPI_PUBLIC_IP_ENABLED.toString(), "true");
        HazelcastInstance client = HazelcastClient.newHazelcastClient(config);

        System.out.println("Successful connection!");
        System.out.println("Starting to fill the map with random entries.");

        IMap<String, String> map = client.getMap("map");
        Random random = new Random();
        while (true) {
            int randomKey = random.nextInt(100_000);
            map.put("key-" + randomKey, "value-" + randomKey);
            System.out.println("Current map size: " + map.size());
        }
    }
}
'use strict';

const { Client } = require('hazelcast-client');

const clientConfig = {
    network: {
        clusterMembers: [
            '<EXTERNAL-IP>'
        ]
    },
    properties: {
        ['hazelcast.discovery.public.ip.enabled']: true
    }
};

(async () => {
    try {
        const client = await Client.newHazelcastClient(clientConfig);
        const map = await client.getMap('map');
        await map.put('key', 'value');
        const res = await map.get('key');
        if (res !== 'value') {
            throw new Error('Connection failed, check your configuration.');
        }
        console.log('Successful connection!');
        console.log('Starting to fill the map with random entries.');
        while (true) {
            const randomKey = Math.floor(Math.random() * 100000);
            await map.put('key' + randomKey, 'value' + randomKey);
            const size = await map.size();
            console.log(`Current map size: ${size}`);
        }
    } catch (err) {
        console.error('Error occurred:', err);
    }
})();
package main

import (
	"context"
	"fmt"
	"math/rand"

	"github.com/hazelcast/hazelcast-go-client"
)

func main() {
	config := hazelcast.Config{}
	cc := &config.Cluster
	cc.Network.SetAddresses("<EXTERNAL-IP>")
	cc.Discovery.UsePublicIP = true
	ctx := context.TODO()
	client, err := hazelcast.StartNewClientWithConfig(ctx, config)
	if err != nil {
		panic(err)
	}
	fmt.Println("Successful connection!")
	fmt.Println("Starting to fill the map with random entries.")
	m, err := client.GetMap(ctx, "map")
	if err != nil {
		panic(err)
	}
	for {
		num := rand.Intn(100_000)
		key := fmt.Sprintf("key-%d", num)
		value := fmt.Sprintf("value-%d", num)
		if _, err = m.Put(ctx, key, value); err != nil {
			fmt.Println("ERR:", err.Error())
		} else {
			if mapSize, err := m.Size(ctx); err != nil {
				fmt.Println("ERR:", err.Error())
			} else {
				fmt.Println("Current map size:", mapSize)
			}
		}
	}
}
import logging
import random

import hazelcast

logging.basicConfig(level=logging.INFO)

client = hazelcast.HazelcastClient(
    cluster_members=["<EXTERNAL-IP>"],
    use_public_ip=True,
)

print("Successful connection!", flush=True)
print("Starting to fill the map with random entries.", flush=True)

m = client.get_map("map").blocking()

while True:
    random_number = str(random.randrange(0, 100000))
    m.put("key-" + random_number, "value-" + random_number)
    print("Current map size:", m.size())
using Hazelcast;
using Microsoft.Extensions.Logging;


class CsharpExample
{
    static async Task Main(string[] args)
    {

        var options = new HazelcastOptionsBuilder()
            .With(args)
            .With((configuration, options) =>
            {
                options.LoggerFactory.Creator = () => LoggerFactory.Create(loggingBuilder => loggingBuilder.AddConfiguration(configuration.GetSection("logging")).AddConsole());
                options.Networking.Addresses.Add("<EXTERNAL-IP>");
                options.Networking.SmartRouting = false;
            })
            .Build();
        var client = await HazelcastClientFactory.StartNewClientAsync(options);


        Console.WriteLine("Successful connection!");
        Console.WriteLine("Starting to fill the map with random entries.");

        var map = await client.GetMapAsync<string, string>("map");
        var random = new Random();
        while (true)
        {
            var randomKey = random.Next(100_000);
            await map.PutAsync("key-" + randomKey, "value-" + randomKey);
            Console.WriteLine("Current map size: " + await map.GetSizeAsync());
        }
    }
}

Now you can start the application.

  • CLC

  • Java

  • NodeJS

  • Go

  • Python

  • .NET

Fill a map:

for i in {1..10};
do
   clc -c hz map set --name map1 key-$i value-$i;
done

Check the map size:

clc -c hz map size --name map1
cd java
mvn package
java -jar target/*jar-with-dependencies*.jar

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd nodejs
npm install
npm start

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd go
go run main.go

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd python
pip install -r requirements.txt
python main.py

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....
cd dotnet
dotnet build
dotnet run

You should see the following output:

Successful connection!
Starting to fill the map with random entries.
Current map size: 2
Current map size: 3
Current map size: 4
....
....

Clean up

To clean up the created resources remove the Hazelcast Custom Resources.

kubectl delete hazelcast my-hazelcast-unisocket
kubectl delete hazelcast my-hazelcast-smart

Summary

In this tutorial, you’ve learned how to connect to a Hazelcast cluster running in Kubernetes from outside of the Kubernetes environment, using both the Unisocket and Smart options.

Next steps

See also:

lifebuoy

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