Use Java EE JCache with Open Liberty or WebSphere Liberty on an Azure Kubernetes Service (AKS) cluster

This article describes how to use Java EE JCache in a containerized application deployed to AKS.

In this guide, you'll:

  • Create the infrastructure to run your Java, Java EE, Jakarta EE, or MicroProfile application on the Open Liberty or WebSphere Liberty runtime.
  • Use Java EE JCache backed by Azure Cache for Redis as session cache.
  • Build the application Docker image using Open Liberty or WebSphere Liberty container images.
  • Deploy the containerized application to an AKS cluster using the Open Liberty Operator.

This article is intended to help you quickly get to deployment. Before going to production, you should explore Tuning Liberty.

If you don't have an Azure subscription, create a free account before you begin.


  • This article requires the latest version of Azure CLI. If you're using Azure Cloud Shell, the latest version is already installed.
  • If you're running the commands in this guide locally (instead of Azure Cloud Shell):
    • Prepare a local machine with Unix-like operating system installed (for example, Ubuntu, macOS, Windows Subsystem for Linux).
    • Install a Java SE implementation, version 17 or later (for example, Eclipse Open J9).
    • Install Maven 3.5.0 or higher.
    • Install Docker for your OS.
  • Be sure you've been assigned either Owner role or Contributor and User Access Administrator roles for the subscription. You can verify your assignments by following steps in List role assignments for a user or group.

Create the infrastructure

The steps in this section guide you to create the application infrastructure on Azure. After completing these steps, you'll have an Azure Container Registry, an Azure Kubernetes Service cluster, and an Azure Cache for Redis instance for running the sample application.

Create a resource group

An Azure resource group is a logical group in which Azure resources are deployed and managed.

Create a resource group called java-liberty-project using the az group create command in the eastus location. This resource group will be used later for creating the Azure Container Registry (ACR) instance and the AKS cluster.

export RESOURCE_GROUP_NAME=java-liberty-project
az group create --name $RESOURCE_GROUP_NAME --location eastus

Create an ACR instance

Use the az acr create command to create the ACR instance. The following example creates an ACR instance named youruniqueacrname. Make sure youruniqueacrname is unique within Azure.

export REGISTRY_NAME=youruniqueacrname
az acr create \
    --resource-group $RESOURCE_GROUP_NAME \
    --name $REGISTRY_NAME \
    --sku Basic \

After a short time, you should see a JSON output that contains:

  "provisioningState": "Succeeded",
  "publicNetworkAccess": "Enabled",
  "resourceGroup": "java-liberty-project",

Alternatively, you can create an Azure container registry instance by following the steps in Quickstart: Create an Azure container registry using the Azure portal.

Connect to the ACR instance

You'll need to sign in to the ACR instance before you can push an image to it. Run the following commands to verify the connection:

export LOGIN_SERVER=$(az acr show \
    --name $REGISTRY_NAME \
    --resource-group $RESOURCE_GROUP_NAME \
    --query 'loginServer' \
    --output tsv)
export USER_NAME=$(az acr credential show \
    --name $REGISTRY_NAME \
    --resource-group $RESOURCE_GROUP_NAME \
    --query 'username' \
    --output tsv)
export PASSWORD=$(az acr credential show \
    --name $REGISTRY_NAME \
    --resource-group $RESOURCE_GROUP_NAME \
    --query 'passwords[0].value' \
    --output tsv)


You should see Login Succeeded at the end of command output if you've signed into the ACR instance successfully.

If you see a problem signing in to the Azure container registry, see Troubleshoot registry login.

Create an AKS cluster

Use the az aks create command to create an AKS cluster and grant it image pull permission from the ACR instance. The following example creates a cluster named myAKSCluster with one node. This command will take several minutes to complete.

export CLUSTER_NAME=myAKSCluster
az aks create \
    --resource-group $RESOURCE_GROUP_NAME \
    --name $CLUSTER_NAME \
    --node-count 1 \
    --generate-ssh-keys \
    --enable-managed-identity \
    --attach-acr $REGISTRY_NAME

After a few minutes, the command completes and returns JSON-formatted information about the cluster, including the following lines:

  "nodeResourceGroup": "MC_java-liberty-project_myAKSCluster_eastus",
  "privateFqdn": null,
  "provisioningState": "Succeeded",
  "resourceGroup": "java-liberty-project",

Connect to the AKS cluster

To manage a Kubernetes cluster, you use kubectl, the Kubernetes command-line client. If you use Azure Cloud Shell, kubectl is already installed. To install kubectl locally, use the az aks install-cli command:

az aks install-cli

To configure kubectl to connect to your Kubernetes cluster, use the az aks get-credentials command. This command downloads credentials and configures the Kubernetes CLI to use them.

az aks get-credentials \
    --resource-group $RESOURCE_GROUP_NAME \
    --name $CLUSTER_NAME \

To verify the connection to your cluster, use the kubectl get command to return a list of the cluster nodes.

kubectl get nodes

The following example output shows the single node created in the previous steps. Make sure that the status of the node is Ready.

NAME                                STATUS   ROLES   AGE     VERSION
aks-nodepool1-xxxxxxxx-yyyyyyyyyy   Ready    agent   76s     v1.18.10

Install Open Liberty Operator

After creating and connecting to the cluster, install the Open Liberty Operator by running the following commands.

# Install cert-manager Operator
kubectl apply -f${CERT_MANAGER_VERSION}/cert-manager.yaml

# Install Open Liberty Operator
mkdir -p overlays/watch-all-namespaces
wget${OPERATOR_VERSION}/kustomize/overlays/watch-all-namespaces/olo-all-namespaces.yaml -q -P ./overlays/watch-all-namespaces
wget${OPERATOR_VERSION}/kustomize/overlays/watch-all-namespaces/cluster-roles.yaml -q -P ./overlays/watch-all-namespaces
wget${OPERATOR_VERSION}/kustomize/overlays/watch-all-namespaces/kustomization.yaml -q -P ./overlays/watch-all-namespaces
mkdir base
wget${OPERATOR_VERSION}/kustomize/base/kustomization.yaml -q -P ./base
wget${OPERATOR_VERSION}/kustomize/base/open-liberty-crd.yaml -q -P ./base
wget${OPERATOR_VERSION}/kustomize/base/open-liberty-operator.yaml -q -P ./base
wget${OPERATOR_VERSION}/kustomize/base/open-liberty-roles.yaml -q -P ./base
kubectl create namespace open-liberty
kubectl apply --server-side -k overlays/watch-all-namespaces

Create an Azure Cache for Redis instance

Azure Cache for Redis backs the persistence of the HttpSession for a Java application running within an Open Liberty or WebSphere Liberty server. Follow the steps in this section to create an Azure Cache for Redis instance and note down its connection information. We'll use this information later.

  1. Follow the steps in Quickstart: Use Azure Cache for Redis in Java up to, but not including Understanding the Java sample.

  2. Copy Host name and Primary access key for your Azure Cache for Redis instance, and then run the following commands to add environment variables:


Build the application

Follow the steps in this section to build and containerize the sample application. These steps use Maven, liberty-maven-plugin, and az acr build. To learn more about the liberty-maven-plugin, see Building a web application with Maven.

Check out the application

Use the following commands to clone the sample code for this guide. The sample is in the open-liberty-on-aks repository on GitHub. There are a few samples in the repository. This article uses java-app-jcache.

git clone
cd open-liberty-on-aks
git checkout 20230906

If you see a message about being in "detached HEAD" state, this message is safe to ignore. It just means you have checked out a tag.

The application has the following file structure:

├── pom.xml
└── src
    └── main
        ├── aks
        │   └── openlibertyapplication.yaml
        ├── docker
        │   ├── Dockerfile
        │   └── Dockerfile-wlp
        ├── java
        ├── liberty
        │   └── config
        │       └── server.xml
        ├── redisson
        │   └── redisson-config.yaml
        ├── resources
        └── webapp

The java, resources, and webapp directories contain the source code of the sample application.

In the aks directory, the deployment file openlibertyapplication.yaml is used to deploy the application image.

In the docker directory, we place two Dockerfiles. Dockerfile is used to build image with Open Liberty and Dockerfile-wlp is used to build image with WebSphere Liberty.

In the liberty/config directory, the server.xml file is used to configure session cache for the Open Liberty and WebSphere Liberty cluster.

In the redisson directory, the redisson-config.yaml file is used to configure the connection of the Azure Cache for Redis instance.

Containerize the application

To deploy and run your Liberty application on the AKS cluster, use the following steps to containerize your application as a Docker image. You can use Open Liberty container images or WebSphere Liberty container images.

  1. Change directory to java-app-jcache of your local clone.

  2. Run mvn clean package to package the application.

  3. Run mvn -Predisson validate to copy the Redisson configuration file to the specified location. This step inserts the values of the environment variables REDISCACHEHOSTNAME and REDISCACHEKEY into the redisson-config.yaml file, which is referenced by the server.xml file.

  4. Run mvn liberty:dev to test the application. If the test is successful, you should see The defaultServer server is ready to run a smarter planet. in the command output. You should see output similar to the following if the Redis connection is successful.

    [INFO] [err] [Default Executor-thread-5] INFO org.redisson.Version - Redisson 3.16.7
    [INFO] [err] [redisson-netty-2-2] INFO org.redisson.connection.pool.MasterPubSubConnectionPool - 1 connections initialized for
    [INFO] [err] [redisson-netty-2-20] INFO org.redisson.connection.pool.MasterConnectionPool - 24 connections initialized for
  5. You can visit http://localhost:9080/ to see the application running, but the proof of Redis working is the output listed in the preceding step.

  6. Use Ctrl+C to stop the application.

  7. Use the following commands to retrieve values for properties artifactId and version defined in the pom.xml file.

    export artifactId=$(mvn -q -Dexec.executable=echo -Dexec.args='${project.artifactId}' --non-recursive exec:exec)
    export version=$(mvn -q -Dexec.executable=echo -Dexec.args='${project.version}' --non-recursive exec:exec)
  8. Run cd target to change directory to the build of the sample.

  9. Run one of the following commands to build the application image and push it to the ACR instance.

    • Use the following command to build with an Open Liberty base image if you prefer to use Open Liberty as a lightweight open source Java™ runtime:

      # Build and tag application image. This will cause the ACR instance to pull the necessary Open Liberty base images.
      az acr build -t ${artifactId}:${version} -r $REGISTRY_NAME --resource-group $RESOURCE_GROUP_NAME .
    • Use the following command to build with a WebSphere Liberty base image if you prefer to use a commercial version of Open Liberty:

      # Build and tag application image. This will cause the ACR instance to pull the necessary WebSphere Liberty base images.
      az acr build -t ${artifactId}:${version} -r $REGISTRY_NAME --resource-group $RESOURCE_GROUP_NAME --file=Dockerfile-wlp .

Deploy the application

Follow the steps in this section to deploy the containerized sample application on the AKS cluster.

  1. Verify the current working directory is java-app-jcache/target in your local clone.

  2. Use the following commands to create a secret with Redisson configuration information. With this secret, the application can connect to the created Azure Cache for Redis instance.

    export REDISSON_CONFIG_SECRET_NAME=redisson-config-secret
    kubectl create secret generic ${REDISSON_CONFIG_SECRET_NAME} --from-file=$(pwd)/liberty/wlp/usr/servers/defaultServer/redisson-config.yaml
  3. Use the following commands to deploy your Liberty application with three replicas to the AKS cluster. The command output is also shown inline.

    # Set number of application replicas
    export REPLICAS=3
    # Create OpenLibertyApplication "javaee-cafe-jcache-cluster"
    envsubst < openlibertyapplication.yaml | kubectl create -f - created
    # Check if OpenLibertyApplication instance is created
    kubectl get openlibertyapplication ${artifactId}-cluster
    NAME                               IMAGE                                                         EXPOSED      RECONCILED   AGE
    javaee-cafe-jcache-cluster                      True         59s
    # Check if deployment created by Operator is ready
    kubectl get deployment ${artifactId}-cluster --watch
    NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
    javaee-cafe-jcache-cluster         0/3     3            0           20s
  4. Wait until you see 3/3 under the READY column and 3 under the AVAILABLE column, then use Ctrl+C to stop the kubectl watch process.

Test the application

When the application runs, a Kubernetes load balancer service exposes the application front end to the internet. This process can take a while to complete.

To monitor progress, use the kubectl get service command with the --watch argument.

kubectl get service ${artifactId}-cluster --watch

NAME                               TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)          AGE
javaee-cafe-jcache-cluster         LoadBalancer    80:31732/TCP     68s

Once the EXTERNAL-IP address changes from pending to an actual public IP address, use Ctrl+C to stop the kubectl watch process.

Open a web browser to the external IP address of your service ( for the above example) to see the application home page. If the page isn't loaded correctly, that's because the app is starting. You can wait for a while and refresh the page later. You should see the pod name of your application replicas displayed at the top-left of the page (javaee-cafe-jcache-cluster-77d54bccd4-5xnzx for this case).

Screenshot of Java liberty application successfully deployed on A K S.

In the form New coffee in session, set values for fields Name and Price, and then select Submit. After a few seconds, you'll see Submit count: 1 displayed at the left bottom of the page.

Screenshot of sample application showing new coffee created and persisted in the session of the application.

To demonstrate that the session cache is persisted across all replicas of the application, run the following command to delete the current replica with pod name javaee-cafe-jcache-cluster-<pod id from your running app>:

kubectl delete pod javaee-cafe-jcache-cluster-77d54bccd4-5xnzx

pod "javaee-cafe-jcache-cluster-77d54bccd4-5xnzx" deleted

Then, refresh the application home page. You'll see the same data displayed in the section New coffee in session but a different pod name displayed at the top-left of the page.

Finally, use the following steps to demonstrate that the session data is persisted in the Azure Cache for Redis instance. You can issue commands to your Azure Cache for Redis instance using the Redis Console.

  1. Find your Azure Cache for Redis instance from the Azure portal.

  2. Select Console to open Redis console.

  3. Run the following commands to view the session data:

    scan 0 count 1000 match '*'
    hgetall ""
  4. Search for cafe.model.entity.Coffee[id=1, name=Coffee 3, price=30.0] from the web page, which is the coffee you created and persisted in the Azure Cache for Redis instance.

Clean up resources

To avoid Azure charges, you should clean up unnecessary resources. When the cluster is no longer needed, use the az group delete command to remove the resource group, container service, container registry, and all related resources.

az group delete --name $RESOURCE_GROUP_NAME --yes --no-wait

To delete the Azure Cache for Redis instance, find its resource group name and run the following command:

az group delete --name <AZURE_CACHE_FOR_REDIS_RESOURCE_GROUP_NAME> --yes --no-wait

Next steps

You can learn more from references used in this guide: