Understanding Ingress Controllers: Converting Ingress Resources to Routing Rules, Configuring Load Balancers, and Enabling SSL

An Ingress Controller is an automated software component that watches Ingress objects in a Kubernetes cluster and converts them into concrete routing rules, injecting those rules into the appropriate services so external traffic can reach backend workloads via specified hostnames and paths.

The controller continuously monitors changes to Ingress objects; when a new rule is added, it creates or updates the corresponding routing table entries and ensures traffic is correctly distributed to the targeted services.

Example of routing rule conversion:

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: myingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: frontend-service
          servicePort: 80
      - path: /api
        backend:
          serviceName: api-service
          servicePort: 8080

In this manifest, requests to example.com/api are routed to api-service:8080 , while all other requests go to frontend-service:80 . The Ingress Controller automatically updates the service routing tables to enforce this behavior.

Load balancer configuration: The controller can also configure a load balancer based on Ingress rules, directing traffic to different backend services.

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress-test
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: webapp1-service
          servicePort: 80
      - path: /app2
        backend:
          serviceName: app2-service
          servicePort: 9000

SSL/TLS configuration: To enable HTTPS, a Secret containing the certificate and private key must be created and referenced in the Ingress manifest.

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: simple-ingress
spec:
  tls:
  - hosts:
    - host.example.com
    secretName: example-tls-secret
  rules:
  - host: host.example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: simple-service
          servicePort: 80

This example binds the example-tls-secret to simple-service:80 , enabling encrypted communication for host.example.com . Users must ensure the Secret exists and the Kubernetes cluster supports SSL/TLS termination.