Ingress

Contents

Exposes a set of services to the outside world. With Ingress, users do not connect directly to a Service. Users reach the Ingress endpoint, and, from there, the request is forwarded to the desired Service. Under the hood, it can use a loadbalancer... but a single one, for many services!

https://www.joyfulbikeshedding.com/blog/2018-03-26-studying-the-kubernetes-ingress-system.html
https://kubernetes.github.io/ingress-nginx/deploy/

ingress controllers / Edge and service proxies

nginx → Ingress/nginx have SEVERAL IMPLEMENTATIONS!
- A community project: ingress-nginx → https://github.com/kubernetes/ingress-nginx/
- A commercial project, led by the company nginx → https://github.com/nginxinc/kubernetes-ingres[[https://github.com/nginxinc/kubernetes-ingress|s]]
HAProxy 2.0
Traefik 2.0
Envoy

IMPORTANT

Ingress is configured with an Ingress resource (defined by a config file, for instance)
Ingress does NOT route traffic itself. It relies on something else (nginx, for example)
Ingress configures and monitors something else (nginx, for example)

→ In K8s terminology, it is a controller

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: virtual-host-ingress
  namespace: default
spec:
  rules:
  - host: blue.example.com
    http:
      paths:
      - backend:
          serviceName: webserver-blue-svc
          servicePort: 80
  - host: green.example.com
    http:
      paths:
      - backend:
          serviceName: webserver-green-svc
          servicePort: 80

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: fan-out-ingress
  namespace: default
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /blue
        backend:
          serviceName: webserver-blue-svc
          servicePort: 80
      - path: /green
        backend:
          serviceName: webserver-green-svc
          servicePort: 80

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress-service
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/rewrite-target: /$1
    # UPDATE THIS LINE ABOVE
spec:
  rules:
    - http:
        paths:
          - path: /?(.*)
            backend:
              serviceName: client-cluster-ip-service
              servicePort: 3000
          - path: /api/?(.*)
            backend:
              serviceName: server-cluster-ip-service
              servicePort: 5000