Ingress

Part of the Kubernetes course

You can already get traffic into the cluster. NodePort opens a high-numbered port on every node; LoadBalancer asks your cloud provider for a public IP. Both work, and both scale badly in the same way: every application needs its own port or its own load balancer, so five apps means five IPs to remember, five certificates to install somewhere, and five bills.

That is an HTTP-level routing decision, and Service cannot make it. A Service works at the level of IP addresses and ports, and it has no idea what a hostname or a URL path is, because that information only exists inside the HTTP request. Ingress is the layer that reads the request and routes on its contents.