Why should you care?

Manual Docker on VMs fails autoscale and self-heal during traffic spikes.

See it live — copy this example

Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.

# k8s/api-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata: { name: meanverse-api }
spec:
  replicas: 3
  selector: { matchLabels: { app: meanverse-api } }
  template:
    metadata: { labels: { app: meanverse-api } }
    spec:
      containers:
        - name: api
          image: ghcr.io/meanverse/api:1.4.0
          ports: [{ containerPort: 3000 }]
          envFrom: [{ secretRef: { name: meanverse-secrets } }]
          readinessProbe:
            httpGet: { path: /health, port: 3000 }

What happened?

• Deployment maintains 3 replicas.
• readinessProbe removes unhealthy pods from Service.
• Secrets inject MONGO_URI without image rebuild.

Practice next

1. Containerize api and push to registry.
2. Apply Deployment, Service, Ingress manifests.
3. Configure HPA on CPU 70% target.
4. Add PodDisruptionBudget minAvailable 2.
5. Use Helm chart parameterize replicas per env.

Remember

K8s orchestrates containers at scale. Probes, secrets, and HPA for production. Immutable image tags per release.

Payroll day traffic

Morning spike 3x normal API load.

Outcome: HPA scales 3 to 12 pods; p95 stable under SLO.