Kubernetes Networking & Scaling
ClusterIP, Ingress, and the Horizontal Pod Autoscaler - how traffic finds pods, and how pods multiply under load.
On this page4 sections
Getting traffic to the right Pods, and making sure there are enough of them, is most of what running Kubernetes in production actually feels like day to day.
Service types
A Service's type decides how it's reachable:
| Type | Reachable from |
|---|---|
ClusterIP (default) | Only inside the cluster |
NodePort | Any cluster node's IP, on a fixed port |
LoadBalancer | The internet, via a cloud provider's load balancer |
Most internal services (a database, an internal API another service calls) stay ClusterIP - no reason to expose them any wider than that.
Ingress
Giving every public-facing service its own cloud load balancer gets expensive and repetitive fast. An Ingress is a single entry point that routes HTTP traffic to many different internal Services, based on hostname or URL path:
example.com/api → api-service
example.com/app → frontend-service
blog.example.com → blog-service
One load balancer, one place to manage TLS certificates, routing rules that live in your cluster's config as code.
Horizontal Pod Autoscaler (HPA)
Rather than someone watching a dashboard and manually running kubectl scale, an HPA does it automatically, based on a metric - CPU usage being the default:
target: 70% average CPU
min replicas: 2
max replicas: 10
Traffic spikes, average CPU climbs past 70%, the HPA adds Pods. Traffic drops back off, and it scales back down - the exact same elastic-scaling idea from the cloud-compute lesson, just applied one layer up, at the Pod level instead of the VM level.
Try it
netstat -tulpn
When you're ready, hit Mark complete and move to the next lesson.
Challenge
List every listening network port on this host - exactly what you'd check if a Service wasn't reaching its pods.
Want to experiment first? Try things in the practice terminal (opens in a new tab), then enter the command that solves the task here.
Quiz
Lock in the concepts. Score at least 80% to mark the lesson complete.
Done with this one?
Skipped the challenge? You can mark the lesson complete by hand.