Skip to main content

Coherence Operator

Coherence Operator​

The Oracle Coherence Operator is an open-source Kubernetes operator that enables the deployment and management of Oracle Coherence clusters in Kubernetes environments. It provides features to assist with deploying, scaling, and managing Coherence data grid clusters using cloud-native technologies. Full Documentation can be found here

Installing the Coherence Operator​

The Coherence Operator will be installed if coherence.enabled is set to true in the values.yaml file. The default namespace for the Coherence Operator is coherence.

Creating a Coherence Cluster​

Follow these steps to create a basic Coherence cluster named mysample-cluster:

Prerequisites​

  • Coherence Operator is installed and running
  • kubectl is configured to access your Kubernetes cluster
  • You have a namespace where you want to deploy the cluster (e.g., coherence)
Step 1: Create the Coherence Cluster YAML​

Create a file named mysample-cluster.yaml with the basic cluster configuration

YAML Configuration Files​

Basic Cluster Configuration (mysample-cluster.yaml):

apiVersion: coherence.oracle.com/v1
kind: Coherence
metadata:
  name: mysample-cluster
spec:
  replicas: 3
  image: ghcr.io/oracle/coherence-ce:22.06.7
  coherence:
    cacheConfig: coherence-cache-config.xml
  jvm:
    memory:
      heapSize: 2g
  ports:
    - name: http
      port: 8080

Cluster with Persistence (mysample-cluster-persistent.yaml):

apiVersion: coherence.oracle.com/v1
kind: Coherence
metadata:
  name: mysample-cluster
spec:
  replicas: 3
  image: ghcr.io/oracle/coherence-ce:22.06.7
  coherence:
    cacheConfig: coherence-cache-config.xml
    persistence:
      mode: active
      persistentVolumeClaim:
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 10Gi
  jvm:
    memory:
      heapSize: 2g
  ports:
    - name: http
      port: 8080
    - name: metrics
      port: 9612
  env:
    - name: OTEL_EXPORTER_OTLP_ENDPOINT
      value: "http://otel-collector:4317"
    - name: OTEL_SERVICE_NAME
      value: "mysample-cluster"
    - name: OTEL_METRICS_EXPORTER
      value: "otlp"
    - name: OTEL_TRACES_EXPORTER
      value: "otlp"

Notes:

  • The replicas field determines the number of pods in the cluster (default: 3)
  • The image field specifies the Coherence container image to use
  • For persistence, ensure your Kubernetes cluster has a default StorageClass configured, or specify one using storageClassName
  • The env section configures OpenTelemetry (OTEL) for metrics and traces export to an OTEL collector
  • The metrics port (9612) exposes Coherence metrics for collection
Step 2: Deploy the Cluster​

Apply the YAML configuration to create the cluster:

kubectl apply -f mysample-cluster.yaml -n coherence
Step 3: Verify the Deployment​

Check that the cluster pods are running:

# Check the Coherence resource
kubectl get coherence -n coherence

# Check the pods
kubectl get pods -n coherence

# View cluster details
kubectl describe coherence mysample-cluster -n coherence

Wait for all pods to reach the Running state. You can watch the progress with:

kubectl get pods -n coherence -w

Using Coherence with Spring Boot​

To connect your Spring Boot application to the mysample-cluster Coherence cluster deployed above, you need to add the following dependencies and configuration. Coherence Spring Documentation

Dependencies​

Maven (pom.xml):

<dependencies>
    <!-- Coherence Spring Boot Starter -->
    <dependency>
        <groupId>com.oracle.coherence.spring</groupId>
        <artifactId>coherence-spring-boot-starter</artifactId>
    </dependency>

    <!-- Coherence CE -->
    <dependency>
        <groupId>com.oracle.coherence.ce</groupId>
        <artifactId>coherence</artifactId>
    </dependency>
</dependencies>

Spring Boot Configuration​

Create or update your application.yaml file to connect to the mysample-cluster:

coherence:
  # Set the instance type to 'client' to connect to an existing cluster
  instance:
    type: client

  # Configure the cluster connection
  cluster:
    name: mysample-cluster

  # Configure sessions
  sessions:
    - name: default
      config: coherence-cache-config.xml
      priority: 1

  # Logging configuration (optional)
  logging:
    destination: slf4j
    logger-name: Coherence

  # Server startup timeout (optional)
  server:
    startup-timeout: 60s