NexisyTech Learningby Nexisy Technologies

Kubernetes Ingress vs Gateway API

Two ways to bring outside traffic into a cluster, and why Gateway API is the successor.

Advanced7 min read3 interview questions

Services inside a cluster are not reachable from the internet by default. Ingress is the original API for HTTP routing into the cluster; the Gateway API is its more expressive, role-oriented successor.

Both are specifications. A controller — NGINX, Traefik, Envoy Gateway, Istio, a cloud load balancer — actually implements the routing.

Diagram

IngressGateway APIIngress controllerIngresshost + path rulesServiceGatewayClassinfra providerGatewaycluster operatorHTTPRouteapp teamService
Ingress uses one resource; Gateway API splits responsibilities across roles.

Key concepts

Ingress
One resource with host and path rules. Advanced features rely on controller-specific annotations.
GatewayClass
Defines which controller implements gateways — set up by the infrastructure provider.
Gateway
A listener (ports, TLS, hostnames) managed by the cluster operator.
HTTPRoute / GRPCRoute
Routing rules owned by application teams, attached to a gateway.
Traffic splitting
Gateway API supports weighted backends natively — useful for canaries.

Trade-offs

Benefits

  • Ingress: simple, mature, supported everywhere
  • Gateway API: role separation, portable advanced routing, TCP/UDP/gRPC routes, header matching and weights

Costs

  • Ingress: annotations differ per controller, so configs are not portable
  • Gateway API: more resources to learn, controller support still varies by feature

Use it when

  • Ingress for simple HTTP routing in existing clusters
  • Gateway API for new platforms, multi-team clusters and canary routing

Common mistakes

  • Relying on controller-specific annotations without documenting them
  • Allowing any namespace to attach routes to a shared gateway
  • Terminating TLS without automating certificate renewal (use cert-manager)

Interview questions

Q1Why was the Gateway API created?
Ingress was limited to basic HTTP routing, with everything else in non-portable annotations. Gateway API provides a richer, standard model and separates infrastructure, operator and developer roles.
Q2Is an API gateway the same as a Kubernetes Gateway?
Not exactly. A Kubernetes Gateway handles traffic entry and routing. Full API gateways add API keys, quotas, developer portals and transformations, though some products do both.
Q3How would you do a canary with Gateway API?
Use an HTTPRoute with two backendRefs — v1 with weight 95 and v2 with weight 5 — and adjust the weights as metrics stay healthy.

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