Troubleshoot Docker-K8s SpringBoot API

I have a simple “Hello World” Spring Boot API that I’ve containerised and already pushed through the full pipeline: the Java code compiles, the Docker image builds, and I have the Kubernetes deployment (2 replicas) and service YAMLs applied on Docker Desktop’s built-in Kubernetes for Windows. Everything comes up healthy from what I can see with kubectl, yet every call I make from Postman ends in a Socket Hangup. I’m not even sure whether the problem sits behind a NodePort, a port-forward, or the container port itself.

What I need first is a solid review of the Docker image, deployment, and service configuration to spot anything that would block traffic, followed by a clear fix so the endpoint responds in Postman without errors. Along the way I’d like concise guidance on testing techniques so I can reproduce the checks myself.

Deliverables
• Updated or confirmed-correct Dockerfile, deployment.yaml, and service.yaml (2 replicas, reachable locally)
• Step-by-step commands or notes showing how you verified connectivity (kubectl, curl, Postman)
• Brief explanation of the root cause and the change that resolved it

If you’re comfortable debugging Spring Boot containers on a local Kubernetes cluster and can walk me through the fix, let’s get it working.