Kubernetes Ingress and Ingress Controllers

Managing external access to the services in a cluster, typically HTTP.

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Kubernetes Ingress

An Ingress is an API object that manages external access to the services in a cluster, typically HTTP. It can provide load balancing, SSL termination, and name-based virtual hosting.

1. The Ingress Resource

The Ingress resource is a set of rules that allow inbound connections to reach the cluster services.

  • Path-based routing: example.com/api goes to service A, example.com/shop goes to service B.
  • Host-based routing: api.example.com goes to service A, shop.example.com goes to service B.

2. The Ingress Controller

The Ingress resource does nothing by itself. You must have an Ingress Controller running in the cluster to fulfill the Ingress.

  • Common controllers include NGINX Ingress Controller, Traefik, HAProxy, and cloud-specific ones like AWS ALB Ingress Controller.
  • It is usually a reverse proxy deployed as a Deployment or DaemonSet.

3. Why use Ingress over LoadBalancer Services?

While a LoadBalancer service creates a new cloud load balancer for every service (which is expensive and hard to manage), an Ingress allows you to use a single IP/Load Balancer to route traffic to dozens of internal services based on the URL path or hostname.