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Israel .O. Ayanda
Israel .O. Ayanda

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Hands-on: Deploy Java Web Application on Kubernetes Cluster on AWS.

In this article explains how you can deploy a containerized java web application into a Kubernetes cluster. This is helpful when your system architecture needs to be high-availability, fault tolerance, easily scalable, portable and platform independent.

In this setup, I have used KOps to deploy the k8s cluster on AWS. However, other alternatives includes AWS EKS a managed service on AWS. I wrote a simple script to provision k8s cluster on AWS EkS using the eksctl tool.

The web application deployed in this tutorial uses docker images. I have containerized the java application as well as the database and are publicly available on my docker registry. I have also used official docker images for RabbitMQ (as the message broker) and Memcached( to speed up the database by reducing the amount of reads on the database.) and finally used AWS route53 as DNS.

Click below list to view the docker images

Prerequisites

Let's Begin!!!

You should skip this step if you are using another cluster setup. This step only starts the cluster and not the cluster setup.

Spin up KOps Cluster in the terminal

Create cluster

kops create cluster --name=kube.oayanda.com --state=s3://oayanda-kops-state --zones=us-east-1a,us-east-1b --node-count=2 --node-size=t3.small --master-size=t3.medium --dns-zone=kube.oayanda.com
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create cluster

Update cluster

 kops update cluster --name kube.oayanda.com --state=s3://oayanda-kops-state --yes --admin
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update cluster

Validate cluster

kops validate cluster --state=s3://oayanda-kops-state
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validate cluster

Create Persistent EBS volume for DB pod. Copy the volume ID for later use. vol-023c6c76a8a8b98ce and the AZ us-east-1a.

Copy the following code snippet into your terminal.

aws ec2 create-volume --availability-zone=us-east-1a --size=5 --volume-type=gp2 --tag-specifications 'ResourceType=volume,Tags=[{Key=KubernetesCluster,Value=kube.oayanda.com}]'
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Note: For volume mapping, make sure the value of the tag is the same as your kubernetes cluster.

validate cluster

Verify from AWS console

validate cluster

Verify which node is located in us-east-1a, which is where the volume was created.

 # Get available Nodes k get nodes # Get more details about a node using the name k describe node <name>
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Note: You can create an alias for kubectl in your terminal. alias k=kubectl

validate cluster

Create custom labels for nodes

# Create label for node k label nodes i-033bf8399b48c258e zone=us-east-1a # Verify label creation k get node i-033bf8399b48c258e --show-labels
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validate cluster

Writing definition Files

Secret definition File
The secret object help to keep sensitive data like password. However, by default, stored unencrypted in the API server's underlying data store (etcd). Anyone with API access can retrieve or modify a Secret, and so can anyone with access to etcd. Read more from official documentation

Encode for the application and RabbitMQ passwords with base64.

echo -n "<password>" | base64
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validate cluster

Create a file app-secret.yaml

apiVersion: v1 kind: Secret metadata: name: app-secret type: Opaque data: db-pass: cGFzcw== rmq-pass: Z3Vlc3Q=
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# create secret object k create -f app-secret.yaml # Show secret k get secret
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Note: for production, the secret definition file should not be public because it might be decoded.

validate cluster

Database definition File
For this file, you need the volume ID you created earlier and the zone the volume was created.

apiVersion: apps/v1 kind: Deployment metadata: name: vprodb labels: app: vprodb spec: selector: matchLabels: app: vprodb replicas: 1 template: metadata: labels: app: vprodb spec: containers: - name: vprodb image: oayanda/vprofiledb:v1 args: - "--ignore-db-dir=lost+found" volumeMounts: - mountPath: /var/lib/mysql name: vpro-db-data ports: - name: vprodb-port containerPort: 3306 env: - name: MYSQL_ROOT_PASSWORD valueFrom: secretKeyRef: name: app-secret key: db-pass nodeSelector: zone: us-east-1a volumes: - name: vpro-db-data awsElasticBlockStore: volumeID: vol-023c6c76a8a8b98ce fsType: ext4
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Create DB deployment

k create -f vprodbdep.yaml k get pod
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validate cluster

Verify volume is attached to pod

k describe pod pod vprodb-58b465f7f-zfth7
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validate cluster

DB Service Definition

This will only be exposed internally to application and not to the public.

Create definition file db-cip.yaml

apiVersion: v1 kind: Service metadata: name: vprodb spec: ports: - port: 3306 targetPort: vprodb-port protocol: TCP selector: app: vprodb type: ClusterI
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Memcached deployment Definition

This will use the official docker image from docker hub.

Create definition file mcdep.yaml

apiVersion: apps/v1 kind: Deployment metadata: name: vpromc labels: app: vpromc spec: selector: matchLabels: app: vpromc replicas: 1 template: metadata: labels: app: vpromc spec: containers: - name: vpromc image: memcached ports: - name: vpromc-port containerPort: 11211
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Memcached Service Definition

This will only be exposed internally to application and not to the public as well.

Create definition file mc-cip.yaml

apiVersion: v1 kind: Service metadata: name: vprocache01 spec: ports: - port: 11211 targetPort: vpromc-port protocol: TCP selector: app: vpromc type: ClusterIP
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RabbitMQ Deployment Definition

This will also use the official docker image from docker hub.

Create definition file mcdep.yaml

apiVersion: apps/v1 kind: Deployment metadata: name: vpromq01 labels: app: vpromq01 spec: selector: matchLabels: app: vpromq01 replicas: 1 template: metadata: labels: app: vpromq01 spec: containers: - name: vpromq01 image: rabbitmq ports: - name: vpromq01-port containerPort: 15672 env: - name: RABBIT_DEFAULT_PASS valueFrom: secretKeyRef: name: app-secret key: rmq-pass - name: RABBIT_DEFAULT_USER value: "guest"
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Rabbitmq Service Definition

This will only be exposed internally to application using the Cluster IP type.

Create definition file mc-cip.yaml

apiVersion: v1 kind: Service metadata: name: vprormq01 spec: ports: - port: 15672 targetPort: vpromq01-port protocol: TCP selector: app: vpromq01 type: ClusterIP
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Java Application Deployment
I have used two inicontainers which are temporary containers which are dependencies for the Java application. Their job is to make sure the database and memcache container service are ready before the Java application container starts.

apiVersion: apps/v1 kind: Deployment metadata: name: vproapp labels: app: vproapp spec: selector: matchLabels: app: vproapp replicas: 1 template: metadata: labels: app: vproapp spec: containers: - name: vproapp image: oayanda/vprofileapp:v1 ports: - name: vproapp-port containerPort: 8080 initContainers: - name: init-mydb image: busybox:1.28 command: ['sh', '-c','until nslookup vprodb; do echo waiting for mydb; sleep 2; done;'] - name: init-memcache image: busybox:1.28 command: ['sh', '-c','until nslookup vprocache01; do echo waiting for memcache ; sleep 2; done;']
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Create Service Load balancer for Java application

apiVersion: v1 kind: Service metadata: name: vproapp-service spec: ports: - port: 80 targetPort: vproapp-port protocol: TCP selector: app: vproapp type: LoadBalancer
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Now, let's deploy all the other definition files

k apply -f .
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validate cluster

Verify deployment and service are created and working

k get deploy,pod,svc
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Note: It might sometime for all objects to created including the Load balancer.

validate cluster

Copy the Load balancer URL and view in browser

load balancer
validate cluster

Login with the default name: admin_vp and password: admin_vp
validate cluster

Host on Rout53
Step 1
If you are using an external registrar (for example, GoDaddy).

  • Create a Hosted Zone in Route53
  • Copy the NS records and update it on your external registrar. Step 2

In the Hosted zone on Rout53
Click create record

create record

  • Enter a name for your application
  • Click on the Alias radio button
  • Under the Route traffic to, select Alias to Application and Classic load balancer
  • Select the region your application is deployed
  • Select the Load balancer
  • Click Create records > This will take some seconds for propagation.

route 53

View in the browser

domain

Clean Up

# Delete all objects k delete -f .
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clean up

Congratulations! you have successfully deploy a java web application on Kubernetes Cluster.

Project Source

You can Clone the project files from my Github

As always, I look forward to getting your thoughts on this article. Please feel free to leave a comment!

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