Kubernetes Ingress Controller

This guide explains how to use Træfik as an Ingress controller in a Kubernetes cluster. If you are not familiar with Ingresses in Kubernetes you might want to read the Kubernetes user guide

The config files used in this guide can be found in the examples directory

Prerequisites

  1. A working Kubernetes cluster. If you want to follow along with this guide, you should setup minikube on your machine, as it is the quickest way to get a local Kubernetes cluster setup for experimentation and development.

  2. The kubectl binary should be installed on your workstation.

Role Based Access Control configuration (Kubernetes 1.6+ only)

Kubernetes introduces Role Based Access Control (RBAC) in 1.6+ to allow fine-grained control of Kubernetes resources and api.

If your cluster is configured with RBAC, you may need to authorize Traefik to use kubernetes API using ClusterRole and ClusterRoleBinding resources:

Note: your cluster may have suitable ClusterRoles already setup, but the following should work everywhere

---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: traefik-ingress-controller
rules:
  - apiGroups:
      - ""
    resources:
      - pods
      - services
      - endpoints
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - extensions
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
---
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

examples/k8s/traefik-rbac.yaml

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-rbac.yaml

Deploy Træfik using a Deployment object

We are going to deploy Træfik with a Deployment, as this will allow you to easily roll out config changes or update the image.

---
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
        resources:
          limits:
            cpu: 200m
            memory: 30Mi
          requests:
            cpu: 100m
            memory: 20Mi
        ports:
        - containerPort: 80
          hostPort: 80
        - containerPort: 8080
        args:
        - --web
        - --kubernetes

examples/k8s/traefik.yaml

notice that we binding port 80 on the Træfik container to port 80 on the host. With a multi node cluster we might expose Træfik with a NodePort or LoadBalancer service and run more than 1 replica of Træfik for high availability.

To deploy Træfik to your cluster start by submitting the deployment to the cluster with kubectl:

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik.yaml

Check the deployment

Now lets check if our deployment was successful.

Start by listing the pods in the kube-system namespace:

$kubectl --namespace=kube-system get pods

NAME                                         READY     STATUS    RESTARTS   AGE
kube-addon-manager-minikubevm                1/1       Running   0          4h
kubernetes-dashboard-s8krj                   1/1       Running   0          4h
traefik-ingress-controller-678226159-eqseo   1/1       Running   0          7m

You should see that after submitting the Deployment to Kubernetes it has launched a pod, and it is now running. It might take a few moments for kubernetes to pull the Træfik image and start the container.

You could also check the deployment with the Kubernetes dashboard, run minikube dashboard to open it in your browser, then choose the kube-system namespace from the menu at the top right of the screen.

You should now be able to access Træfik on port 80 of your minikube instance.

curl $(minikube ip)
404 page not found

We expect to see a 404 response here as we haven't yet given Træfik any configuration.

Deploy Træfik using Helm Chart

Instead of installing Træfik via a Deployment object, you can also use the Træfik Helm chart.

Install Træfik chart by:

helm install stable/traefik

For more information, check out the doc.

Submitting An Ingress to the cluster.

Lets start by creating a Service and an Ingress that will expose the Træfik Web UI.

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

examples/k8s/ui.yaml

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/ui.yaml

Now lets setup an entry in our /etc/hosts file to route traefik-ui.local to our cluster.

In production you would want to set up real dns entries.

You can get the ip address of your minikube instance by running minikube ip

echo "$(minikube ip) traefik-ui.local" | sudo tee -a /etc/hosts

We should now be able to visit traefik-ui.local in the browser and view the Træfik Web UI.

Name based routing

In this example we are going to setup websites for 3 of the United Kingdoms best loved cheeses, Cheddar, Stilton and Wensleydale.

First lets start by launching the 3 pods for the cheese websites.

---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: stilton
  labels:
    app: cheese
    cheese: stilton
spec:
  replicas: 2
  selector:
    matchLabels:
      app: cheese
      task: stilton
  template:
    metadata:
      labels:
        app: cheese
        task: stilton
        version: v0.0.1
    spec:
      containers:
      - name: cheese
        image: errm/cheese:stilton
        resources:
          requests:
            cpu: 100m
            memory: 50Mi
          limits:
            cpu: 100m
            memory: 50Mi
        ports:
        - containerPort: 80
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: cheddar
  labels:
    app: cheese
    cheese: cheddar
spec:
  replicas: 2
  selector:
    matchLabels:
      app: cheese
      task: cheddar
  template:
    metadata:
      labels:
        app: cheese
        task: cheddar
        version: v0.0.1
    spec:
      containers:
      - name: cheese
        image: errm/cheese:cheddar
        resources:
          requests:
            cpu: 100m
            memory: 50Mi
          limits:
            cpu: 100m
            memory: 50Mi
        ports:
        - containerPort: 80
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: wensleydale
  labels:
    app: cheese
    cheese: wensleydale
spec:
  replicas: 2
  selector:
    matchLabels:
      app: cheese
      task: wensleydale
  template:
    metadata:
      labels:
        app: cheese
        task: wensleydale
        version: v0.0.1
    spec:
      containers:
      - name: cheese
        image: errm/cheese:wensleydale
        resources:
          requests:
            cpu: 100m
            memory: 50Mi
          limits:
            cpu: 100m
            memory: 50Mi
        ports:
        - containerPort: 80

examples/k8s/cheese-deployments.yaml

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheese-deployments.yaml

Next we need to setup a service for each of the cheese pods.

---
apiVersion: v1
kind: Service
metadata:
  name: stilton
spec:
  ports:
  - name: http
    targetPort: 80
    port: 80
  selector:
    app: cheese
    task: stilton
---
apiVersion: v1
kind: Service
metadata:
  name: cheddar
spec:
  ports:
  - name: http
    targetPort: 80
    port: 80
  selector:
    app: cheese
    task: cheddar
---
apiVersion: v1
kind: Service
metadata:
  name: wensleydale
  annotations:
    traefik.backend.circuitbreaker: "NetworkErrorRatio() > 0.5"
spec:
  ports:
  - name: http
    targetPort: 80
    port: 80
  selector:
    app: cheese
    task: wensleydale

Notice that we also set a circuit breaker expression for one of the backends by setting the traefik.backend.circuitbreaker annotation on the service.

examples/k8s/cheese-services.yaml

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheese-services.yaml

Now we can submit an ingress for the cheese websites.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: cheese
  annotations:
    kubernetes.io/ingress.class: traefik
spec:
  rules:
  - host: stilton.local
    http:
      paths:
      - path: /
        backend:
          serviceName: stilton
          servicePort: http
  - host: cheddar.local
    http:
      paths:
      - path: /
        backend:
          serviceName: cheddar
          servicePort: http
  - host: wensleydale.local
    http:
      paths:
      - path: /
        backend:
          serviceName: wensleydale
          servicePort: http

examples/k8s/cheese-ingress.yaml

Notice that we list each hostname, and add a backend service.

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheese-ingress.yaml

Now visit the Træfik dashboard and you should see a frontend for each host. Along with a backend listing for each service with a Server set up for each pod.

If you edit your /etc/hosts again you should be able to access the cheese websites in your browser.

echo "$(minikube ip) stilton.local cheddar.local wensleydale.local" | sudo tee -a /etc/hosts

Path based routing

Now lets suppose that our fictional client has decided that while they are super happy about our cheesy web design, when they asked for 3 websites they had not really bargained on having to buy 3 domain names.

No problem, we say, why don't we reconfigure the sites to host all 3 under one domain.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: cheeses
  annotations:
    kubernetes.io/ingress.class: traefik
    traefik.frontend.rule.type: pathprefixstrip
spec:
  rules:
  - host: cheeses.local
    http:
      paths:
      - path: /stilton
        backend:
          serviceName: stilton
          servicePort: http
      - path: /cheddar
        backend:
          serviceName: cheddar
          servicePort: http
      - path: /wensleydale
        backend:
          serviceName: wensleydale
          servicePort: http

examples/k8s/cheeses-ingress.yaml

Notice that we are configuring Træfik to strip the prefix from the url path with the traefik.frontend.rule.type annotation so that we can use the containers from the previous example without modification.

kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheeses-ingress.yaml
echo "$(minikube ip) cheeses.local" | sudo tee -a /etc/hosts

You should now be able to visit the websites in your browser.

Disable passing the Host header

By default Træfik will pass the incoming Host header on to the upstream resource. There are times however where you may not want this to be the case. For example if your service is of the ExternalName type.

Disable entirely

Add the following to your toml config:

disablePassHostHeaders = true

Disable per ingress

To disable passing the Host header per ingress resource set the traefik.frontend.passHostHeader annotation on your ingress to false.

Here is an example ingress definition:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: example
  annotations:
    kubernetes.io/ingress.class: traefik
    traefik.frontend.passHostHeader: "false"
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /static
        backend:
          serviceName: static
          servicePort: https

And an example service definition:

apiVersion: v1
kind: Service
metadata:
  name: static
spec:
  ports:
  - name: https
    port: 443
  type: ExternalName
  externalName: static.otherdomain.com

If you were to visit example.com/static the request would then be passed onto static.otherdomain.com/static and static.otherdomain.com would receive the request with the Host header being static.otherdomain.com.

Note: The per ingress annotation overides whatever the global value is set to. So you could set disablePassHostHeaders to true in your toml file and then enable passing the host header per ingress if you wanted.

Excluding an ingress from Træfik

You can control which ingress Træfik cares about by using the kubernetes.io/ingress.class annotation. By default if the annotation is not set at all Træfik will include the ingress. If the annotation is set to anything other than traefik or a blank string Træfik will ignore it.