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Compose to Kubernetes Concept Map

This table maps a small Compose service to the Kubernetes objects in hello-k8s.yaml.

Compose snippet (conceptual)

services:
  web:
    image: nginx:1.27-alpine
    ports:
      - "8080:80"
    deploy:
      replicas: 2

Kubernetes equivalents

Compose idea Kubernetes object / field
services.web Deployment named hello
image: nginx:1.27-alpine spec.template.spec.containers[].image
deploy.replicas: 2 spec.replicas: 2
ports published to host Service + kubectl port-forward or NodePort / Ingress (production)
Service DNS name web Service metadata.name hello; Pods reach it as hello in-cluster

Apply and verify (local cluster required)

kubectl apply -f hello-k8s.yaml
kubectl get deployments,pods,svc
NAME    READY   UP-TO-DATE   AVAILABLE
hello   2/2     2            2

NAME         TYPE        CLUSTER-IP     PORT(S)
hello        ClusterIP   10.x.x.x       80/TCP

kubectl port-forward service/hello 8080:80
Forwarding from 127.0.0.1:8080 -> 80

curl -s -o /dev/null -w "%{http_code}\n" http://127.0.0.1:8080
200

What Compose still does better (for now)

  • Fastest loop on one machine: docker compose up
  • Simpler mental model for Module 08 labs

What Kubernetes adds

  • Schedules Pods across many nodes
  • Built-in rolling updates via Deployment controller
  • RBAC, Namespaces, and cloud integrations at scale