Pinter Computing

In the previous post, Learn Kubernetes part 2 – NGINX Ingress Controller, we have deployed a web application and exposed it via the kubernetes/ingress-nginx ingress controller.

In this exercise we will use Traefik, another popular proxy server. Traefik is widely used for multiple reasons: it is easier to configure, can automatically generate and renew SSL certificates using Let’s Encrypt. We will also use most of the scripts from the prior exercise.

Create the Traefik Role Based Access Control with ClusterRoleBinding. This will allow Traefik to serve all namespaces of the cluster. To restrict the Traefik to one namespace only, use the “namespace-specific RoleBindings”.

traefik-rbac.yaml (Based on https://docs.traefik.io/user-guide/kubernetes/)

---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: traefik-ingress-controller
rules:
  - apiGroups:
      - ""
    resources:
      - services
      - endpoints
      - secrets
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - extensions
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
  - apiGroups:
    - extensions
    resources:
    - ingresses/status
    verbs:
    - update
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: traefik-ingress-controller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: traefik-ingress-controller
subjects:
- kind: ServiceAccount
  name: traefik-ingress-controller
  namespace: kube-system

Deploy Traefik with a deployment. This introduces a few more network hops, but follows the Kubernetes best practices guidelines and provides more flexibility.

traefik-deployment.yaml (Based on https://docs.traefik.io/user-guide/kubernetes/)

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: traefik-ingress-controller
  namespace: kube-system
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: traefik-ingress-controller
  namespace: kube-system
  labels:
    k8s-app: traefik-ingress-lb
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: traefik-ingress-lb
  template:
    metadata:
      labels:
        k8s-app: traefik-ingress-lb
        name: traefik-ingress-lb
    spec:
      serviceAccountName: traefik-ingress-controller
      terminationGracePeriodSeconds: 60
      containers:
      - image: traefik
        name: traefik-ingress-lb
        ports:
        - name: http
          containerPort: 80
        - name: admin
          containerPort: 8080
        args:
        - --api
        - --kubernetes
        - --logLevel=INFO
---
kind: Service
apiVersion: v1
metadata:
  name: traefik-ingress-service
  namespace: kube-system
spec:
  selector:
    k8s-app: traefik-ingress-lb
  ports:
    - protocol: TCP
      port: 80
      name: web
    - protocol: TCP
      port: 8080
      name: admin
  type: NodePort

Create the resources

Launch the scripted resources

kubectl apply -f .

Check the Traefik pods. List the pods in the kube-system namespace, and make sure the “traefik-ingress-controller” is running.

kubectl --namespace=kube-system get pods

Expose the Traefik Web UI with a service

To be able to access the Traefik Web UI we will create a service and an ingress to expose it outside of the cluster.

ui.yaml (Based on https://docs.traefik.io/user-guide/kubernetes/)

---
apiVersion: v1
kind: Service
metadata:
  name: traefik-web-ui
  namespace: kube-system
spec:
  selector:
    k8s-app: traefik-ingress-lb
  ports:
  - name: web
    port: 80
    targetPort: 8080
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: traefik-web-ui
  namespace: kube-system
spec:
  rules:
  - host: traefik-ui.minikube
    http:
      paths:
      - path: /
        backend:
          serviceName: traefik-web-ui
          servicePort: web

Create the resources

Launch the scripted resources

kubectl apply -f .

Check the ingress

List the cluster ingresses

kubectl get ingress --all-namespaces

NAMESPACE     NAME             HOSTS                 ADDRESS   PORTS   AGE
kube-system   traefik-web-ui   traefik-ui.minikube             80      53s

Access the Kubernetes cluster via Traefik

To be able to access the traefik-ui.minikube host we need to modify the /etc/hosts file. Add the host to the file with the localhost IP address.

echo "127.0.0.1 traefik-ui.minikube" | sudo tee -a /etc/hosts

==================================

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

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