Learn Kubernetes part 2 – NGINX Ingress Controller

Large organizations need to control the incoming traffic to the Kubernetes cluster. The most secure way is to use an ingress controller and create an ingress to channel all incoming traffic to the cluster.

In Learn Kubernetes part 1 – Web application in a Kubernetes cluster we have created a simple web application pod and exposed it to the outside world with a service using a load balancer. We will use the files we have created in that exercise with one change. The deployment is the same:

app1-frontend-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app1-frontend-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: app1-frontend-template-label
  template:
    metadata:
      labels:
        app: app1-frontend-template-label
    spec:
      containers:
        - name: app1-frontend-container-label
          image: nginx:1.7.9
          ports:
          - containerPort: 80

In this exercise we will expose the service via an NGINX ingress controller. Delete type: LoadBalancer in the app1-frontend-service.yaml file, so Kubernetes will use type: ClusterIP, the default value.

app1-frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: app1-frontend-service
spec:
  selector:
    app: app1-frontend-template-label
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 80

Create an ingress controller

In this example we will use the kubernetes/ingress-nginx ingress controller maintained by the Kubernetes community. See kubernetes/ingress-nginx NGINX Ingress Controller Installation Guide to configure the NGINX Ingress Controller in your environment.

To start the kubernetes/ingress-nginx ingress controller in any operating system, execute this command to create the ‘nginx-ingress-controller’ deployment with containers

• k8s_nginx-ingress-controller_nginx-ingress-controller
• k8s_POD_nginx-ingress-controller

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml

Based on the operating system, also execute this to create the ‘ingress-nginx’ service

On Macintosh

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/cloud-generic.yaml

Verify the ingress controller installation to make sure it has successfully started

kubectl get pods --all-namespaces -l app.kubernetes.io/name=ingress-nginx --watch

NAMESPACE       NAME                                        READY   STATUS    RESTARTS   AGE
ingress-nginx   nginx-ingress-controller-86449c74bb-rlx6h   1/1     Running   0          2d4h

Script the ingress

Connect the ingress to the service

Set the name of the service in the spec: … backend: serviceName:

ingress_nginx.yaml

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress
spec:
  rules:
  - http:
      paths:
      - path: /
        backend:
          serviceName: app1-frontend-service
          servicePort: 80

Create the resources

To launch the application and configure the resources to expose it outside of the Kubernetes cluster, open a terminal in the directory where you saved the files and execute

 kubectl apply -f .

Verify the ingress

List the ingresses

kubectl get ingress

NAME      HOSTS   ADDRESS     PORTS   AGE
ingress   *       localhost   80      59s

To verify the ingress execute

kubectl describe ingress MY_INGRESS_NAME

Troubleshooting Kubernetes Ingress-Nginx

See Troubleshooting Kubernetes Ingress-Nginx

See Kubernetes Ingress Controllers for more info.

Accessing the application

To access the application through the ingress, open a web browser and access the application via the ADDRESS and PORTS values: http://localhost:80

The browser will display a warning, click the Advanced button

Click the Proceed to localhost (unsafe) link

You should see the NGINX default page

Delete the resources

If you want to delete these resources from the Kubernetes cluster, execute

kubectl delete -f .

Delete the ingress controller service

kubectl delete service ingress-nginx -n ingress-nginx

Delete the deployment

kubectl delete deployment nginx-ingress-controller -n ingress-nginx

Delete the ingress-nginx service

kubectl delete -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/cloud-generic.yaml

Delete the ‘nginx-ingress-controller’ deployment

kubectl delete -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml

Check if all ingress pods are deleted

kubectl get pods --all-namespaces -l app.kubernetes.io/name=ingress-nginx --watch

Next: Learn Kubernetes part 3 – Traefik Ingress Controller