Hazelcast supports connections from both smart and unisocket clients that are outside your Kubernetes cluster. To allow these clients to connect to Hazelcast, you need to configure the `exposeExternally` field of the Hazelcast custom resource.
| For a working example, see this tutorial. |
Environmental Constraints
The kubectl command-line tool must be configured to communicate with your cluster.
Google Kubernetes Engine (GKE)
If you use GKE, consider the following:
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Make sure the Kubernetes cluster is public.
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If you plan on using NodePorts, (
discoveryServiceType: NodePortormemberAccess: NodePortExternalIP), set up a firewall rule for each Hazelcast member to allow TCP traffic on node ports.
Amazon Elastic Kubernetes Service (EKS)
If you use EKS, consider the following:
-
Having the VPC of the EKS cluster configured only with private subnets is not recommended.
-
If you plan on using NodePorts, (
discoveryServiceType: NodePortormemberAccess: NodePortExternalIP), the VPC of the EKS cluster should be configured only with public subnets. Additionally, inbound rules for the node ports should be added to the nodes' security groups.
Azure Kubernetes Service (AKS)
If you use AKS, consider the following:
-
Make sure the Kubernetes cluster is public.
-
If you plan on using NodePorts, (
discoveryServiceType: NodePortormemberAccess: NodePortExternalIP), the node pools should be created by using the--enable-node-public-ipflag. Additionally, the required inbound rules should be added for network security groups (NSGs) to allow access to node IPs and ports.
Configuring exposeExternally
To allow connections from clients, you need to configure the exposeExternally field, of the Hazelcast custom resource.
If using Istio, you cannot use exposeExternally.
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This field has the following properties:
| Property | Description | ||
|---|---|---|---|
|
The way in which Hazelcast members are exposed to clients:
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Type of Kubernetes service used for discovering members in a Hazelcast cluster:
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The way in which clients access Hazelcast members:
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If NodePorts are used (discoveryServiceType: NodePort or memberAccess: NodePortExternalIP), the Kubernetes nodes must allow external TCP traffic on node IPs and ports.
|
Exposing Hazelcast to Smart Clients
Smart clients access partitioned data in a cluster by communicating with the partition owner. This operation mode increases the overall throughput and efficiency of client-cluster communication.
| For non-partitioned data, smart clients can communicate with any cluster member. |
To support smart clients, you should configure the type property as smart.
In this configuration, the standard Kubernetes mechanism routes client traffic to the correct member. Or, if the client is not accessing partitioned data, the traffic is automatically load balanced.
Exposing Hazelcast to Unisocket Clients
Unisocket clients communicate with a single member in the cluster. To enable these clients to connect to the Hazelcast cluster, you should configure the type property as unisocket.
In this configuration, the standard Kubernetes mechanism automatically load balances client traffic across the Hazelcast cluster.
Example Configuration
In this example, the Hazelcast cluster is configured to load balance connections from smart clients.
apiVersion: hazelcast.com/v1alpha1
kind: Hazelcast
metadata:
name: hazelcast-sample
spec:
clusterSize: 3
repository: 'docker.io/hazelcast/hazelcast-enterprise'
version: '5.5-slim'
licenseKeySecretName: hazelcast-license-key
exposeExternally:
type: Smart
discoveryServiceType: LoadBalancer
memberAccess: NodePortExternalIPThis configuration creates a load balancer for the discovery service and one service for each member.
kubectl get serviceNAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hazelcast-sample LoadBalancer 10.219.246.19 35.230.92.217 5701:30560/TCP 2m11s (1)
hazelcast-sample-0 NodePort 10.219.254.192 <none> 5701:31890/TCP 2m11s (2)
hazelcast-sample-1 NodePort 10.219.247.43 <none> 5701:32310/TCP 2m11s (2)
hazelcast-sample-2 NodePort 10.219.243.16 <none> 5701:32585/TCP 2m11s (2)| 1 | Discovery service |
| 2 | Member access service |
The command below allows you to list the external addresses of the cluster.
kubectl get hazelcastendpoint --selector="app.kubernetes.io/instance=hazelcast-sample"NAME TYPE ADDRESS
hazelcast-sample Discovery 35.238.20.134:5701
hazelcast-sample-0 Member 34.122.120.18:30108
hazelcast-sample-1 Member 34.27.85.200:32012
hazelcast-sample-2 Member 34.173.81.209:30512
hazelcast-sample-wan WAN 35.238.20.134:5710Smart clients can use the external IP of the load balancer to connect to the cluster.
ClientConfig config = new ClientConfig();
config.getNetworkConfig().addAddress("35.230.92.217");
config.getProperties().setProperty(ClientProperty.DISCOVERY_SPI_PUBLIC_IP_ENABLED.toString(), "true");
HazelcastInstance client = HazelcastClient.newHazelcastClient(config);const { Client } = require('hazelcast-client');
const clientConfig = {
network: {
clusterMembers: [
'35.230.92.217'
]
},
properties: {
['hazelcast.discovery.public.ip.enabled']: true
}
};
const client = await Client.newHazelcastClient(clientConfig);import (
"context"
"github.com/hazelcast/hazelcast-go-client"
)
func main() {
config := hazelcast.Config{}
cc := &config.Cluster
cc.Network.SetAddresses("35.230.92.217")
cc.Discovery.UsePublicIP = true
ctx := context.TODO()
client, err := hazelcast.StartNewClientWithConfig(ctx, config)
if err != nil {
panic(err)
}
}import logging
import hazelcast
logging.basicConfig(level=logging.INFO)
client = hazelcast.HazelcastClient(
cluster_members=["35.230.92.217"],
use_public_ip=True,
)