What is an Ingress ?

An Ingress resource allows exposing Services outside the cluster. There are other solutions to do so, such as:

• a NodePort Service
• a Load Balancer Service

Use case examples:

• HTTP routing via domain name or query content
• TLS termination

An Ingress resource is used by an Ingress Controller

Ingress controller

An Ingress controller is a reverse proxy configured with Ingress resources.
Among the existing solutions:

• Nginx
• Traefik
• HAProxy
• Kong
• Contour
• Gloo

Routing using domain name

The following specification defines an Ingress resource which ensures the traffic arriving at api.example.com is forwarded to the api Service on port 80:

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

Exposing the VotingApp with an Ingress resource

The previous exercise left the app with the following components:

We will now use an Ingress Controller (based on Traefik) and an Ingress resource to make the application available to the outside world: