How to Use Host Based Routing Ingress in Kubernetes

Use a kubernetes Ingress resource with rules specifying different host values. Each host routes traffic to a specific service inside the cluster, enabling host based routing.

Syntax

An Ingress resource uses rules to define host based routing. Each rule has a host field and http.paths that specify which service to send traffic to.

• host: The domain name to match in the request.
• http: Contains paths for routing.
• paths: List of URL paths and backend services.
• backend.service.name: The Kubernetes service to route to.
• backend.service.port.number: The port of the service.

yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: example-service
            port:
              number: 80
  - host: test.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: test-service
            port:
              number: 80

Example

This example shows an Ingress that routes requests to example.com to example-service and requests to test.com to test-service. Each service listens on port 80.

yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: host-routing-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: example-service
            port:
              number: 80
  - host: test.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: test-service
            port:
              number: 80

Output

ingress.networking.k8s.io/host-routing-ingress created

Common Pitfalls

• Not specifying host in rules causes all hosts to route to the same backend.
• Forgetting to set pathType can cause routing issues; use Prefix for most cases.
• Ingress controller must support host based routing; check your controller documentation.
• DNS must point the hostnames to the Ingress controller's external IP.

yaml

Wrong example (missing host):
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: wrong-ingress
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: my-service
            port:
              number: 80

Right example (with host):
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: correct-ingress
spec:
  rules:
  - host: mysite.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: my-service
            port:
              number: 80

Quick Reference

• Use host in Ingress rules to route by domain name.
• Set pathType to Prefix for path matching.
• Ensure your DNS points to the Ingress controller IP.
• Verify your Ingress controller supports host based routing.

Key Takeaways

Define multiple rules with different host values in your Ingress to enable host based routing.

Always specify pathType as Prefix for common path matching behavior.

Make sure DNS entries for your hosts point to the Ingress controller's external IP.

Check that your Ingress controller supports host based routing before configuring.

Avoid missing host fields to prevent routing all traffic to a single backend.