Deploy your first app

This guide takes a container image and gets it running on Kubernetes as a Deployment, then exposes it inside the cluster with a Service. The steps work on any conformant cluster, for example a shoot from your own Gardener landscape or a cluster I run for you.

1. Point kubectl at your cluster

Download your cluster’s kubeconfig and confirm you can reach it:

export KUBECONFIG=~/Downloads/paasbox-kubeconfig.yaml
kubectl get nodes

You should see your nodes listed as Ready.

2. Create a namespace

Keep your app’s objects together in their own namespace:

kubectl create namespace demo

3. Deploy the app

A Deployment runs and supervises your container, replacing Pods that crash or get rescheduled. Save this as deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
  namespace: demo
spec:
  replicas: 2
  selector:
    matchLabels: { app: web }
  template:
    metadata:
      labels: { app: web }
    spec:
      containers:
        - name: web
          image: nginxdemos/hello:plain-text
          ports:
            - containerPort: 80
          resources:
            requests: { cpu: 50m, memory: 64Mi }
            limits: { cpu: 250m, memory: 128Mi }

Apply it and watch the Pods come up:

kubectl apply -f deployment.yaml
kubectl -n demo get pods -w

Always set resource requests. They tell the scheduler how much CPU and memory your Pods need. That is what lets the cluster place more workloads on fewer nodes, which is where the savings come from.

4. Expose it with a Service

A Service gives your Pods one stable address inside the cluster, load-balanced across replicas:

apiVersion: v1
kind: Service
metadata:
  name: web
  namespace: demo
spec:
  selector: { app: web }
  ports:
    - port: 80
      targetPort: 80

kubectl apply -f service.yaml

5. Try it

Port-forward the Service to your machine and hit it:

kubectl -n demo port-forward service/web 8080:80
# in another terminal:
curl localhost:8080

You should get a response from the app. 🎉

Next steps

• Run more copies and let the cluster scale them: Scale & autoscale workloads.
• Serve it from the public internet over HTTPS: Expose your app with Ingress & TLS. It builds directly on the app you just deployed.

Clean up

kubectl delete namespace demo