How does Ingress work under the hood in Kubernetes? At what level of the OSI model?

Ingress in Kubernetes is an object that manages external access to services within a cluster, usually via HTTP/HTTPS.

Under the hood, Ingress operates as a controller (Ingress Controller), which:

• Listens for changes to Ingress objects.
• Configures a load balancer or proxy (e.g., NGINX, Traefik).
• Routes HTTP(S) traffic to the appropriate services based on rules (host, path).

Ingress operates at layer 7 of the OSI model (Application layer), as it analyzes HTTP requests for routing.

The network traffic itself passes through TCP (layer 4), but the routing logic and rules are at the HTTP level.