It (only) starts with containers

This repository contains sample code for the talk "It (only) starts with containers" which demonstrates various approaches to deploying a Java application in Kubernetes.

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WARNING: These yaml files are of "works on my cluster" kind. You will need to modify your domain and ingress settings to something that works in your environment.

The Application

The sample application is a Jakarta EE REST service built with:

• Java 21 and Jakarta EE 10
• Payara Micro as the runtime
• MicroProfile Config for configuration
• Simple REST endpoints for demonstration

Features

• GET /hello - Returns a greeting message
• Configurable default name via hello.defaultName property
• Optional downstream service calls to demonstrate service-to-service communication
• Hostname detection for tracing requests across instances

Deployment Approaches

This repository demonstrates 6 different approaches to deploy the same Java application to Kubernetes:

1. Plain YAML (01-yaml/)

Direct Kubernetes manifests with all resources defined explicitly.

• instance-1.yaml - Complete deployment with Namespace, ConfigMap, Deployment, Service, and Ingress
• instance-2.yaml - Second instance with different configuration

2. Kustomize (02-kustomize/)

Template-free customization of Kubernetes objects using overlays.

• base/ - Base manifests
• first-instance/, second-instance/, third-instance/ - Environment-specific overlays
• both-instances/ - Deploy multiple instances together -- doesn't work. Need to be sorted with ArgoCD

3. Helm (03-helm/)

Package manager for Kubernetes with templating capabilities.

• container-app/ - Helm chart with templates
• *-values.yaml - Environment-specific value files
• combined/ - Multi-instance deployment using same base chart

4. Pulumi (04-pulumi/)

Infrastructure as Code using familiar programming languages.

• container-app/ - Pulumi project for deployment automation in Java

5. ArgoCD (05-argocd/)

GitOps continuous delivery tool for Kubernetes.

• Application definitions for managing deployments
• project.yml - ArgoCD project configuration
• References to the other deployment approaches

6. Domain Keep-Alive (06-domain-keepalive/)

Utility deployment to keep demo domains active.

Getting Started

Building the Application

cd container-app
mvn clean package

Running Locally

mvn clean package payara-micro:dev

Building Container Image

mvn package docker:push # change the image name you hopefully cannot push under my creds in Docker Hub
# Image: pdudits/container-talk-demo:latest

Deploying to Kubernetes

Choose your preferred deployment method:

Plain YAML:

kubectl apply -f 01-yaml/instance-1.yaml

Kustomize:

kubectl apply -k 02-kustomize/first-instance/

Helm:

helm install first-instance 03-helm/container-app/ -f 03-helm/first-instance-values.yaml

Pulumi:

cd 04-pulumi/container-app
pulumi up

Configuration

Each deployment approach demonstrates different configuration methods:

• Environment-specific default names
• Resource limits and requests
• Ingress configurations for external access
• Service-to-service communication setup

Talk Objectives

This repository illustrates the evolution from simple container deployment to sophisticated GitOps workflows, showing:

1. The progression of tooling complexity
2. Trade-offs between simplicity and maintainability
3. How each approach addresses different operational needs
4. Best practices for production deployments

The talk emphasizes that while containers are the starting point, production-ready deployments require thoughtful consideration of deployment strategies, configuration management, and operational workflows.