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k8s-spring-boot-helloworld

Taking the Basic Hello World Application in Spring Boot! further. This example creates a docker container containing a Spring Boot application with a Controller that returns "Hello World!" which gets deployed to a kubernetes cluster using helm.

Note: Refer docker-spring-boot-helloworld repo.

Prerequisites

• Java IDE (I am using IntelliJ CE)
• Maven
• Docker
• Helm
• Tiller on the Kubernetes cluster

System Configuration at time of test

• macOS Catalina - Version 10.15.3 (19D76)
• IntelliJ CE - Version CE 2019.3
• Maven - Version 3.6.1
• Docker Desktop - Version 2.2.0.3 (42716)
• Kubernetes - v1.15.5
• Helm - v2.14.3

Initial Setup

Installing tiller

Run the following commands to install tiller if already not installed on your local cluster

kubectl -n kube-system create serviceaccount tiller

kubectl create clusterrolebinding tiller \
  --clusterrole cluster-admin \
  --serviceaccount=kube-system:tiller

helm init --service-account tiller

Creating Spring project

Follow the steps outlined in docker-spring-boot-helloworld GitHub project to create a Spring Boot docker container.

The basic commands required to create a container are"

mvn clean install
docker build -t spring-boot-helloworld:v1 .

Adding Helm charts

Making the docker container ready to be deployed on kubernetes using helm create the necessary charts by running command helm create {chart name} in this case the chart name should be same as the the project name in this case spring-boot-helloworld. This will create a folder with that name and add default chart templates. Here is the link to the documentation of the files created.

Look the modified code in the spring-boot-helloworld directory. The files to look at are templates/deployment.yaml, templates/service.yaml, and values.yaml. The application is exposed on port 31000 which is defines as the nodePort value in the values.yaml file.

Validate the created charts

To validate the created helm charts run the following command:

helm lint ./spring-boot-helloworld-chart/

Run Helm Install

To install the app using kubernetes run the following command:

helm install --name spring-boot-helloworld -f ./spring-boot-helloworld-chart/values.yaml ./spring-boot-helloworld-chart/

Alternatively you can also use upgrade command with the --install flag:

helm upgrade spring-boot-helloworld ./spring-boot-helloworld-chart/ -f ./spring-boot-helloworld-chart/values.yaml --install --namespace default

Run Helm List

To view the installed app run the following command:

helm list

Run Helm Update

To update the application run the following command:

helm upgrade spring-boot-helloworld ./spring-boot-helloworld-chart/ -f ./spring-boot-helloworld-chart/values.yaml --namespace default

Test

Run the following command to ensure the server is running: curl http://localhost:31000/helloworld/

You can also view it in the browser by going to http://localhost:31000/helloworld/ and following response will show up:

Cleanup

To stop the container that is running use this command: helm delete --purge spring-boot-helloworld

Useful links

• https://github.com/ameyrupji/docker-nginx-static-html-demo
• https://stackify.com/guide-docker-java/
• https://helm.sh/docs/helm/

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