Step‑by‑Step Guide to Deploy a SpringBoot App on Kubernetes

SpringBoot Application Running on K8s

This article explains how to deploy a SpringBoot web application to a Kubernetes cluster, outlining six essential steps: writing the application code, building a container image, creating Pods, scheduling with a Deployment, exposing via a Service, and routing through an Ingress.

Write the Application Code

We start with a minimal HelloWorld‑level SpringBoot project managed by Maven. The pom.xml includes the spring-boot-starter-parent and the Spring MVC starter.

The source code is straightforward, demonstrating that SpringBoot handles much of the boilerplate for us.

Package the Application as a Container Image

Create a Dockerfile in the project root:

FROM openjdk:8-jre
ADD target/*.jar /application.jar
ENTRYPOINT ["java", "-jar", "/application.jar"]

Build and push the image to a remote registry:

docker build -t registry.cn-hangzhou.aliyuncs.com/docker-study-lab/simple-app-java:v0.1

docker push registry.cn-hangzhou.aliyuncs.com/docker-study-lab/simple-app-java:v0.1

Create the Deployment

Deployment is a composite controller that wraps a ReplicaSet, which manages pod replicas. Deployment adds rolling updates, health checks, and rollback capabilities.

Use the following YAML (image omitted for brevity) to define the Deployment. Initially copying a Go example caused OOM errors because the Java container needed more memory; increasing the limit to 500 MiB resolved the issue.

Expose the Service

After creating the Deployment, expose the application internally with a ClusterIP Service. The Service definition (image omitted) prepares for external exposure via Ingress.

Proxy the Service with Ingress

Install an Ingress controller (e.g., ingress‑nginx) and apply the Ingress YAML (image omitted) to route external traffic to the Service. After applying, access the app via java-app.example.com after adding the host entry to /etc/hosts.

Common kubectl Commands

kubectl apply -f xxx.yaml – create or update resources

kubectl get pod|deploy|svc|ingress – view resource status

kubectl describe pod|deploy|svc|ingress {$objectName} – detailed info

kubectl delete pod|deploy|svc|ingress {$objectName} – delete resources

Conclusion

This guide completes a basic end‑to‑end deployment of a SpringBoot app on Kubernetes, covering essential concepts and commands for beginners.

Compared to Go, Java applications typically consume more memory and result in larger container images (around 280 MiB versus a few megabytes for Go), highlighting trade‑offs in cloud‑native environments.