This is the final blog in a series of posts that explore different options for running Java EE workloads on Azure. In this part, we will run the Java EE app on a Kubernetes cluster in Azure.
The example used in the blog post is a simple three-tier application that uses Java EE 8 specifications such as JAX-RS, EJB, CDI, JPA, JSF, Bean Validation. We will use the Payara Server to deploy the application and use PostgreSQL as the relational database.
During the course of the tutorial, we will cover:
- Postgres setup on Azure
- Setup and configure Azure Kubernetes Service cluster and Azure Container Registry
- Dockerize the Java EE app
- Deploy the application to Kubernetes
- Explore its functionality
Except for minor changes, the application used in this tutorial has been adapted from this project by Reza Rahman
Pre-requisites
You will need a Microsoft Azure account and the Azure CLI to work through the tutorial.
If you don't have a Microsoft Azure account, go ahead and sign up for a free one!. The Azure CLI is a cross-platform command-line experience for managing Azure resources - please install it using these instructions.
First things first...
Set your Azure Subscription ID using the Azure CLI which will be used for this tutorial.
To set your Azure subscription ID
export AZURE_SUBSCRIPTION_ID=[to be filled]
az account set --subscription $AZURE_SUBSCRIPTION_ID
Create a resource group that will contain all the services (resources) which you will create as a part of this tutorial. A resource group is like a logical container that holds related resources for an Azure solution. The resource group includes those resources that you want to manage as a group.
To create a resource group
export AZURE_RESOURCE_GROUP_NAME=[to be filled]
export AZURE_LOCATION=[to be filled]
az group create --name $AZURE_RESOURCE_GROUP_NAME --location $AZURE_LOCATION
Install Postgres on Azure
Azure Database for PostgreSQL is a relational database service based on the open-source Postgres database engine. It's a fully managed database-as-a-service offering which is available in two deployment options, as a single server and as a Hyperscale (Citus) cluster
We will be using the single server option for the purposes of this tutorial
We will use the az postgres server create
command to create a Postgres server instance on Azure. First, set up some of the server properties such as the name, admin user, etc.
export AZURE_POSTGRES_SERVER_NAME=[to be filled]
export AZURE_POSTGRES_ADMIN_USER=[to be filled]
export AZURE_POSTGRES_ADMIN_PASSWORD=[to be filled]
export SKU=B_Gen5_1
export STORAGE=5120
For storage and SKU options, please refer to the documentation
And, then invoke the command to initiate the database instance creation:
az postgres server create --resource-group $AZURE_RESOURCE_GROUP_NAME --name $AZURE_POSTGRES_SERVER_NAME --location $AZURE_LOCATION --admin-user $AZURE_POSTGRES_ADMIN_USER --admin-password $AZURE_POSTGRES_ADMIN_PASSWORD --storage-size $STORAGE --sku-name $SKU
The provisioning process will take a few minutes.
To check the details of the Postgres database instance you just provisioned, invoke az postgres server show
command
az postgres server show --resource-group $AZURE_RESOURCE_GROUP_NAME --name $AZURE_POSTGRES_SERVER_NAME
You should get a JSON response. Please note down the value for the fullyQualifiedDomainName
attribute as you will be using this to connect to the Postgres instance later.
It should be of the format:
[AZURE_POSTGRES_DB_NAME].postgres.database.azure.com
Azure Kubernetes Service (AKS) cluster setup
You need the az aks create
command to stand up a Kubernetes cluster on Azure
To keep things simple, the below command creates a single node cluster. Feel free to change the specification as per your requirements
export AKS_CLUSTER_NAME=[to be filled]
az aks create --resource-group $AZURE_RESOURCE_GROUP --name $AKS_CLUSTER_NAME --node-count 1 --node-vm-size Standard_B2s --node-osdisk-size 30 --generate-ssh-keys
Get the AKS cluster credentials using az aks get-credentials
- as a result, kubectl
will now point to your new cluster. You can confirm the same
az aks get-credentials --resource-group $AZURE_RESOURCE_GROUP --name $AKS_CLUSTER_NAME
kubectl get nodes
If you are interested in learning Kubernetes and Containers using Azure, simply create a free account and get going! A good starting point is to use the quickstarts, tutorials and code samples in the documentation to familiarize yourself with the service. I also highly recommend checking out the 50 days Kubernetes Learning Path. Advanced users might want to refer to Kubernetes best practices or the watch some of the videos for demos, top features and technical sessions.
Allow AKS to access the Postgres database
The Postgres database is not accessible to external services by default. We can use the az postgres server firewall-rule create
command to create a firewall rule to explicitly allow Azure services to access the Postgres instance. This will allow the JavaEE application deployed in AKS to communicate with Postgres.
export FIREWALL_RULE_NAME=AllowJavaEECafeAppOnAKS
az postgres server firewall-rule create --resource-group $AZURE_RESOURCE_GROUP_NAME --server-name $AZURE_POSTGRES_SERVER_NAME --start-ip-address=0.0.0.0 --end-ip-address=0.0.0.0 --name $FIREWALL_RULE_NAME
Note: This setting allows network connections from all IPs within the Azure network. For production use, try to configure the most restrictive firewall rules possible
Setup Azure Container Registry
Azure Container Registry is a managed, private Docker registry service to store and manage your private Docker container images (it based on the open-source Docker Registry 2.0). You can use Azure container registries with your existing container development and deployment pipelines, or use Azure Container Registry Tasks to build container images in Azure. You can either build on-demand, or fully automate builds with triggers such as source code commits and base image updates.
Let's create a registry to store the Docker image for the JavaEE application. We will use the az acr create
command
export ACR_NAME=[to-be-filled]
az acr create --resource-group $AZURE_RESOURCE_GROUP_NAME --name $ACR_NAME --sku Basic --admin-enabled true
We are using the
Basic
SKU. Valid value are:Basic
,Classic
,Premium
,Standard
You can log in to the registry once it's created and check the login server
az acr login --name $ACR_NAME
az acr show --name $ACR_NAME --query loginServer --output table
You will use the ACR login server name soon. Its value follows the format:
[ACR_NAME].azurecr.io
Configure Azure Container Registry to work with Azure Kubernetes Service
To access images stored in Azure Container Registry
, you must grant the Azure Kubernetes Service
service principal the correct rights to pull images from ACR.
Get the appId
of the service principal which is associated with your AKS cluster
AKS_SERVICE_PRINCIPAL_APPID=$(az aks show --name $AKS_CLUSTER_NAME --resource-group $AZURE_RESOURCE_GROUP --query servicePrincipalProfile.clientId -o tsv)
Find the resource ID for Azure Container Registry
ACR_RESOURCE_ID=$(az acr show --resource-group $AZURE_RESOURCE_GROUP --name $ACR_NAME --query "id" --output tsv)
Grant acrpull
permissions to AKS service principal
az role assignment create --assignee $AKS_SERVICE_PRINCIPAL_APPID --scope $ACR_RESOURCE_ID --role acrpull
Our AKS cluster along with ACR is ready to use!
Setup and prepare application image
Clone the git repository
git clone https://github.com/abhirockzz/javaee-on-azure-kubernetes
cd javaee-on-azure-kubernetes
You need to enter the Postgres connectivity information to the <url>
attribute of the <data-source
section in web.xml
.
You can find the
web.xml
file underjavaee-on-azure-iaas/src/main/webapp/WEB-INF
The format is as follows:
jdbc:postgresql://[POSTGRES_FQDN]:5432/postgres?user=[AZURE_POSTGRES_ADMIN_USER]@[AZURE_POSTGRES_SERVER_NAME]&password=[AZURE_POSTGRES_ADMIN_PASSWORD]&sslmode=require
Here are the list placeholders which form a part of the JDBC URL:
-
POSTGRES_FQDN
with value offullyQualifiedDomainName
-
AZURE_POSTGRES_ADMIN_USER
with admin user name used to provision PG -
AZURE_POSTGRES_SERVER_NAME
with server name used to provision PG -
AZURE_POSTGRES_ADMIN_PASSWORD
with admin password used to provision PG
Set the required values
export POSTGRES_FQDN=[to be filled]
export AZURE_POSTGRES_ADMIN_USER=[to be filled]
export AZURE_POSTGRES_SERVER_NAME=[to be filled]
export AZURE_POSTGRES_ADMIN_PASSWORD=[to be filled]
Simply use these commands to replace
export FILE_NAME=javaee-on-azure-iaas/src/main/webapp/WEB-INF/web.xml
sed -i 's/POSTGRES_FQDN/'"$POSTGRES_FQDN"'/g' $FILE_NAME
sed -i 's/AZURE_POSTGRES_SERVER_NAME/'"$AZURE_POSTGRES_SERVER_NAME"'/g' $FILE_NAME
sed -i 's/AZURE_POSTGRES_ADMIN_USER/'"$AZURE_POSTGRES_ADMIN_USER"'/g' $FILE_NAME
sed -i 's/AZURE_POSTGRES_ADMIN_PASSWORD/'"$AZURE_POSTGRES_ADMIN_PASSWORD"'/g' $FILE_NAME
Here is an e.g. of what the <data-source>
section will look like:
<data-source>
<name>java:global/JavaEECafeDB</name>
<class-name>org.postgresql.ds.PGPoolingDataSource</class-name>
<url>jdbc:postgresql://foobar-pg.postgres.database.azure.com:5432/postgres?user=foobar@foobar-pg&password=foobarbaz&sslmode=require</url>
</data-source>
The application is now configured. Let's build it!
mvn clean install
You should have the WAR file available. To confirm
ls -lrt target | grep javaee-cafe.war
Build and push the image to Azure Container Registry
Our application artifact (WAR
file) is ready. We can now build the Docker image and push it out to Azure Container Registry. Here is a quick look at the Dockerfile used for this
FROM payara/server-full
COPY target/javaee-cafe.war $DEPLOY_DIR
RUN wget https://jdbc.postgresql.org/download/postgresql-42.2.8.jar
RUN cp /opt/payara/postgresql-42.2.8.jar ${PAYARA_DIR}/glassfish/domains/${DOMAIN_NAME}/lib && rm /opt/payara/postgresql-42.2.8.jar
EXPOSE 8080
It builds on top of the base image for payara/server-full
, copies the WAR
file to a folder from where it can be automatically detected and deployed, downloads the Postgres JDBC driver and places it in the appropriate location for the Payara application server. That's it!
export DOCKER_IMAGE=javaee-cafe
docker build -t $DOCKER_IMAGE .
docker tag $DOCKER_IMAGE $ACR_NAME.azurecr.io/$DOCKER_IMAGE
To push the image
docker push $ACR_NAME.azurecr.io/$DOCKER_IMAGE
For e.g. if the ACR_NAME
(name of the Azure Container Registry) is javaeecafe-acr
, the resulting Docker image will be javaeecafe-acr.azurecr.io/javaee-cafe
Use az acr repository list
command to check the image.
az acr repository list --name $ACR_NAME --output table
Deploy the application to Azure Kubernetes Service
Before deploying the application, please update the Kubernetes manifest file javaee-cafe.yaml
with the name of the Docker image. To be specific, update the spec.containers.image
with the name of the Azure Container Registry which you specified above
It is assumed that the name of the Docker image is
javaee-azure
, if not please update that as well
spec:
containers:
- name: javaee-cafe
image: <replace_me>.azurecr.io/javaee-azure
For e.g.
spec:
containers:
- name: javaee-cafe
image: javaeecafe-acr.azurecr.io/javaee-azure
To deploy the application
kubectl apply -f javaee-cafe.yml
This should spin up a Pod
. Wait for it to transition to Running
state.
kubectl get pods -l=app=javaee-cafe -w
Once the Pod
is Running
, confirm that the application has been deployed successfully
kubectl logs -f <replace_with_pod_name>
The application deployment should be in progress and finally, you should see the logs similar to the one below (with the Successfully autodeployed
message)
[AutoDeploy] Successfully autodeployed : /foo/bar/payara5/glassfish/domains/domain1/autodeploy/javaee-cafe.war.]]
Explore the application
We use a LoadBalancer
Service
type to ensure that our Java EE app is accessible outside of the cluster. The creation of a Kubernetes LoadBalancer
Service
in Azure does exactly what it's supposed to i.e. provision an Azure Load Balancer behind the scenes.
apiVersion: v1
kind: Service
metadata:
name: javaee-cafe
spec:
type: LoadBalancer
ports:
- port: 80
targetPort: 8080
selector:
app: javaee-cafe
We can get the load balancer IP by using
kubectl get svc javaee-cafe
where
javaee-cafe
is the name of theService
The value of the EXTERNAL-IP
is the load balancer IP and will be used to access the application
Access the JSF front end
Use your browser to access http://[LOAD_BALANCER_IP]/javaee-cafe
. You can use the UI to create, delete and see coffees.
Use the REST API
The application also exposes a REST API for creating, deleting and listing coffees.
export JAVAEE_AKS_REST=http://[LOAD_BALANCER_IP]/javaee-cafe/rest/coffees
e.g.
export JAVAEE_AKS_REST=http://23.101.24.139/javaee-cafe/rest/coffees
Create coffees
curl -X POST $JAVAEE_AKS_REST -d '{"name":"cappuccino","price":"10"}' -H "Content-Type: application/json"
curl -X POST $JAVAEE_AKS_REST -d '{"name":"caffe-latte","price":"15"}' -H "Content-Type: application/json"
Get all coffees
curl -H "Accept: application/json" $JAVAEE_AKS_REST
You should see a JSON response listing both the coffee options you just added
Get a coffee by ID
curl -H "Accept: application/json" $JAVAEE_AKS_REST/1
Delete a coffee by ID
curl -X DELETE $JAVAEE_AKS_REST/1
curl -H "Accept: application/json" $JAVAEE_AKS_REST
Notice that cappuccino
is now deleted
Scale
Right now, we have one instance of our application since we had set spec.replicas
to 1
in the Kubernetes manifest. We can scale our application horizontally and Kubernetes will ensure that it spins up and maintains the required number of Pod
s. To add another instance
kubectl scale deployment javaee-cafe --replicas=2
To confirm that another Pod
has been spun up:
kubectl get pods -l=app=javaee-cafe -w
You can continue accessing the application in the same manner and now the requests will be transparently load balanced amongst your app instances by the Load Balancer.
Clean up resources
Once you are done exploring the application, you can delete the resources. Since we used a resource group, it's as easy as executing a single command.
Please be aware that this will delete all the resources in the group which includes the ones you created as part of the tutorial as well as any other service instances you might have if you used an already existing resource group
az group delete --name $AZURE_RESOURCE_GROUP_NAME
Summary
You learned how to leverage Docker containers to package your Java EE application and deploy it on a Kubernetes cluster in Azure along with a managed database offering for long term persistence.
That brings us to the end of this series exploring some of the common ways of deploying Java EE workloads to Azure. I hope you found it useful! 🙌
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