Launching Spring Boot, Quarkus, and microservices on Kubernetes involves containerizing your applications and then deploying them onto a Kubernetes cluster. Here's a high-level overview of the process for each:

1. Spring Boot Application:

1. Containerize the Application:

   • Create a Dockerfile in the root directory of your Spring Boot project:

       FROM openjdk:11-jre-slim
       COPY target/my-spring-app.jar /app.jar
       ENTRYPOINT ["java","-jar","/app.jar"]
     

   • Build the Docker image:

       docker build -t my-spring-app .
     

   • Push the Docker image to a container registry (e.g., Docker Hub):

       docker push <registry>/<image-name>:<tag>
     

2. Define Kubernetes Resources:

   • Create a Deployment YAML file (spring-app-deployment.yaml):

       apiVersion: apps/v1
       kind: Deployment
       metadata:
         name: spring-app-deployment
       spec:
         replicas: 3
         selector:
           matchLabels:
             app: spring-app
         template:
           metadata:
             labels:
               app: spring-app
           spec:
             containers:
             - name: spring-app
               image: <registry>/<image-name>:<tag>
               ports:
               - containerPort: 8080
     

   • Create a Service YAML file (spring-app-service.yaml):

       apiVersion: v1
       kind: Service
       metadata:
         name: spring-app-service
       spec:
         selector:
           app: spring-app
         ports:
         - protocol: TCP
           port: 80
           targetPort: 8080
     

3. Apply Kubernetes Resources:

   • Apply the Deployment and Service YAML files:

       kubectl apply -f spring-app-deployment.yaml
       kubectl apply -f spring-app-service.yaml
     

2. Quarkus Application:

1. Containerize the Application:

   • Follow similar steps as for Spring Boot but adjust the Dockerfile for Quarkus.

2. Define Kubernetes Resources:

   • Create Deployment and Service YAML files similar to the Spring Boot example.

3. Apply Kubernetes Resources:

   • Apply the Deployment and Service YAML files using kubectl apply.

3. Microservices:

1. Containerize the Application:

   • Containerize each microservice following the same steps as for Spring Boot and Quarkus.

2. Define Kubernetes Resources:

   • Create separate Deployment and Service YAML files for each microservice.

   • Optionally, configure Ingress for external access.

3. Apply Kubernetes Resources:

   • Apply the Deployment and Service YAML files for each microservice.

Additional Considerations:

• Networking: Ensure proper networking configuration for inter-service communication.

• Persistence: Configure PersistentVolumeClaims (PVCs) if needed.

• Secrets Management: Use Kubernetes Secrets for sensitive data.

• Monitoring and Logging: Set up monitoring and logging solutions.

• Scaling: Utilize Kubernetes Horizontal Pod Autoscaler if needed.

By following these steps, you can successfully deploy Spring Boot, Quarkus, and microservices applications on Kubernetes, leveraging the power of container orchestration for scalability, reliability, and manageability.