Question

Your cluster runs two Ingress controllers: an NGINX controller (IngressClass 'nginx') for internal apps and an AWS ALB controller (IngressClass 'alb') for public apps. A developer creates an Ingress resource for a public app but omits both the 'spec.ingressClassName' field and the 'kubernetes.io/ingress.class' annotation. The 'nginx' IngressClass has the annotation 'ingressclass.kubernetes.io/is-default-class: "true"'. The public app is unreachable from the internet. What is the most likely cause?

Accepted Answer

The Ingress was claimed by the NGINX controller because 'nginx' is the default IngressClass, so no ALB was provisioned for the public app.

Answer

An Ingress without an ingressClassName is ignored by every controller, so no controller processed the resource at all.

Answer

Both controllers processed the Ingress simultaneously, causing a routing conflict that dropped all external traffic.

Answer

The ALB controller processed the Ingress but requires a matching NetworkPolicy before it can expose the app externally.