Kubernetes Ingress Controller¶
This guide explains how to use Træfik as an Ingress controller for 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
- 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.
The guide is likely not fully adequate for a production-ready setup.
kubectlbinary 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 will need to authorize Træfik to use the Kubernetes API. There are two ways to set up the proper permission: Via namespace-specific RoleBindings or a single, global ClusterRoleBinding.
RoleBindings per namespace enable to restrict granted permissions to the very namespaces only that Træfik is watching over, thereby following the least-privileges principle. This is the preferred approach if Træfik is not supposed to watch all namespaces, and the set of namespaces does not change dynamically. Otherwise, a single ClusterRoleBinding must be employed.
RoleBindings per namespace are available in Træfik 1.5 and later. Please use ClusterRoleBindings for older versions.
For the sake of simplicity, this guide will use a ClusterRoleBinding:
--- 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 --- 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
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-rbac.yaml
For namespaced restrictions, one RoleBinding is required per watched namespace along with a corresponding configuration of Træfik's
Deploy Træfik using a Deployment or DaemonSet¶
- The scalability can be much better when using a Deployment, because you will have a Single-Pod-per-Node model when using a DaemonSet, whereas you may need less replicas based on your environment when using a Deployment.
- DaemonSets automatically scale to new nodes, when the nodes join the cluster, whereas Deployment pods are only scheduled on new nodes if required.
- DaemonSets ensure that only one replica of pods run on any single node. Deployments require affinity settings if you want to ensure that two pods don't end up on the same node.
- DaemonSets can be run with the
NET_BIND_SERVICEcapability, which will allow it to bind to port 80/443/etc on each host. This will allow bypassing the kube-proxy, and reduce traffic hops. Note that this is against the Kubernetes Best Practices Guidelines, and raises the potential for scheduling/scaling issues. Despite potential issues, this remains the choice for most ingress controllers.
- If you are unsure which to choose, start with the Daemonset.
The Deployment objects looks like this:
--- 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
The Service will expose two NodePorts which allow access to the ingress and the web interface.
The DaemonSet objects looks not much different:
--- apiVersion: v1 kind: ServiceAccount metadata: name: traefik-ingress-controller namespace: kube-system --- kind: DaemonSet apiVersion: extensions/v1beta1 metadata: name: traefik-ingress-controller namespace: kube-system labels: k8s-app: traefik-ingress-lb spec: 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 hostPort: 80 - name: admin containerPort: 8080 securityContext: capabilities: drop: - ALL add: - NET_BIND_SERVICE 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
This will create a Daemonset that uses privileged ports 80/8080 on the host. This may not work on all providers, but illustrates the static (non-NodePort) hostPort binding. The
traefik-ingress-service can still be used inside the cluster to access the DaemonSet pods.
To deploy Træfik to your cluster start by submitting one of the YAML files to the cluster with
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-deployment.yaml
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-ds.yaml
There are some significant differences between using Deployments and DaemonSets:
- The Deployment has easier up and down scaling possibilities. It can implement full pod lifecycle and supports rolling updates from Kubernetes 1.2. At least one Pod is needed to run the Deployment.
- The DaemonSet automatically scales to all nodes that meets a specific selector and guarantees to fill nodes one at a time. Rolling updates are fully supported from Kubernetes 1.7 for DaemonSets as well.
Check the Pods¶
Now lets check if our command was successful.
Start by listing the pods in the
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 or DaemonSet 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
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 when using the DaemonSet:
curl $(minikube ip)
404 page not found
If you decided to use the deployment, then you need to target the correct NodePort, which can be seen when you execute
kubectl get services --namespace=kube-system.
curl $(minikube ip):<NODEPORT>
404 page not found
We expect to see a 404 response here as we haven't yet given Træfik any configuration.
All further examples below assume a DaemonSet installation. Deployment users will need to append the NodePort when constructing requests.
Deploy Træfik using Helm Chart¶
The Helm Chart is maintained by the community, not the Træfik project maintainers.
Instead of installing Træfik via Kubernetes object directly, you can also use the Træfik Helm chart.
Install the Træfik chart by:
helm install stable/traefik
Install the Træfik chart using a values.yaml file.
helm install --values values.yaml stable/traefik
dashboard: enabled: true domain: traefik-ui.minikube kubernetes: namespaces: - default - kube-system
For more information, check out the documentation.
Submitting an Ingress to the Cluster¶
Lets start by creating a Service and an Ingress that will expose the Træfik Web UI.
apiVersion: v1 kind: Service metadata: name: traefik-web-ui namespace: kube-system spec: selector: k8s-app: traefik-ingress-lb ports: - name: web port: 80 targetPort: 8080 --- apiVersion: extensions/v1beta1 kind: Ingress metadata: name: traefik-web-ui namespace: kube-system spec: rules: - host: traefik-ui.minikube http: paths: - path: / backend: serviceName: traefik-web-ui servicePort: web
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/ui.yaml
Now lets setup an entry in our
/etc/hosts file to route
traefik-ui.minikube to our cluster.
In production you would want to set up real DNS entries.
You can get the IP address of your minikube instance by running
echo "$(minikube ip) traefik-ui.minikube" | sudo tee -a /etc/hosts
We should now be able to visit traefik-ui.minikube in the browser and view the Træfik web UI.
Add a TLS Certificate to the Ingress¶
For this example to work you need a TLS entrypoint. You don't have to provide a TLS certificate at this point. For more details see here.
To setup an HTTPS-protected ingress, you can leverage the TLS feature of the ingress resource.
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: traefik-web-ui namespace: kube-system annotations: kubernetes.io/ingress.class: traefik spec: rules: - host: traefik-ui.minikube http: paths: - backend: serviceName: traefik-web-ui servicePort: 80 tls: - secretName: traefik-ui-tls-cert
In addition to the modified ingress you need to provide the TLS certificate via a Kubernetes secret in the same namespace as the ingress. The following two commands will generate a new certificate and create a secret containing the key and cert files.
openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=traefik-ui.minikube" kubectl -n kube-system create secret tls traefik-ui-tls-cert --key=tls.key --cert=tls.crt
If there are any errors while loading the TLS section of an ingress, the whole ingress will be skipped.
The secret must have two entries named
See the Kubernetes documentation for more details.
The TLS certificates will be added to all entrypoints defined by the ingress annotation
If no such annotation is provided, the TLS certificates will be added to all TLS-enabled
hosts in the TLS configuration is ignored. Instead, the domains provided by the certificate are used for this purpose.
It is recommended to not use wildcard certificates as they will match globally.
It's possible to protect access to Træfik through basic authentication. (See the Kubernetes Ingress configuration page for syntactical details and restrictions.)
Creating the Secret¶
htpasswd to create a file containing the username and the MD5-encoded password:
htpasswd -c ./auth myusername
You will be prompted for a password which you will have to enter twice.
htpasswd will create a file with the following:
B. Now use
kubectl to create a secret in the
monitoring namespace using the file created by
kubectl create secret generic mysecret --from-file auth --namespace=monitoring
Secret must be in same namespace as the Ingress object.
C. Attach the following annotations to the Ingress object:
They specify basic authentication and reference the Secret
mysecret containing the credentials.
Following is a full Ingress example based on Prometheus:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: prometheus-dashboard namespace: monitoring annotations: kubernetes.io/ingress.class: traefik traefik.ingress.kubernetes.io/auth-type: "basic" traefik.ingress.kubernetes.io/auth-secret: "mysecret" spec: rules: - host: dashboard.prometheus.example.com http: paths: - backend: serviceName: prometheus servicePort: 9090
You can apply the example as following:
kubectl create -f prometheus-ingress.yaml -n monitoring
In this example we are going to setup websites for three of the United Kingdoms best loved cheeses: Cheddar, Stilton, and Wensleydale.
First lets start by launching the 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 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 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 ports: - containerPort: 80
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
We also set a circuit breaker expression for one of the backends by setting the
traefik.backend.circuitbreaker annotation on the service.
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.minikube http: paths: - path: / backend: serviceName: stilton servicePort: http - host: cheddar.minikube http: paths: - path: / backend: serviceName: cheddar servicePort: http - host: wensleydale.minikube http: paths: - path: / backend: serviceName: wensleydale servicePort: http
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 "$(minikube ip) stilton.minikube cheddar.minikube wensleydale.minikube" | sudo tee -a /etc/hosts
Now lets suppose that our fictional client has decided that while they are super happy about our cheesy web design, when they asked for 3 websites they had not really bargained on having to buy 3 domain names.
No problem, we say, why don't we reconfigure the sites to host all 3 under one domain.
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: cheeses annotations: kubernetes.io/ingress.class: traefik traefik.frontend.rule.type: PathPrefixStrip spec: rules: - host: cheeses.minikube http: paths: - path: /stilton backend: serviceName: stilton servicePort: http - path: /cheddar backend: serviceName: cheddar servicePort: http - path: /wensleydale backend: serviceName: wensleydale servicePort: http
We are configuring Træfik to strip the prefix from the url path with the
traefik.frontend.rule.type annotation so that we can use the containers from the previous example without modification.
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheeses-ingress.yaml
echo "$(minikube ip) cheeses.minikube" | sudo tee -a /etc/hosts
You should now be able to visit the websites in your browser.
Specifying Routing Priorities¶
Sometimes you need to specify priority for ingress routes, especially when handling wildcard routes.
This can be done by adding the
traefik.frontend.priority annotation, i.e.:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: wildcard-cheeses annotations: traefik.frontend.priority: "1" spec: rules: - host: *.minikube http: paths: - path: / backend: serviceName: stilton servicePort: http kind: Ingress metadata: name: specific-cheeses annotations: traefik.frontend.priority: "2" spec: rules: - host: specific.minikube http: paths: - path: / backend: serviceName: stilton servicePort: http
Note that priority values must be quoted to avoid numeric interpretation (which are illegal for annotations).
Forwarding to ExternalNames¶
When specifying an ExternalName, Træfik will forward requests to the given host accordingly and use HTTPS when the Service port matches 443. This still requires setting up a proper port mapping on the Service from the Ingress port to the (external) Service port.
Disable passing the Host Header¶
By default Træfik will pass the incoming Host header to the upstream resource.
However, there are times when you may not want this to be the case. For example, if your service is of the ExternalName type.
Add the following to your TOML configuration file:
disablePassHostHeaders = true
Disable per Ingress¶
To disable passing the Host header per ingress resource set the
traefik.frontend.passHostHeader annotation on your ingress to
Here is an example 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 on to
static.otherdomain.com would receive the request with the Host header being
The per-ingress annotation overrides whatever the global value is set to.
So you could set
true in your TOML configuration file and then enable passing the host header per ingress if you wanted.
Partitioning the Ingress object space¶
By default, Træfik processes every Ingress objects it observes. At times, however, it may be desirable to ignore certain objects. The following sub-sections describe common use cases and how they can be handled with Træfik.
Between Træfik and other Ingress controller implementations¶
Sometimes Træfik runs along other Ingress controller implementations. One such example is when both Træfik and a cloud provider Ingress controller are active.
kubernetes.io/ingress.class annotation can be attached to any Ingress object in order to control whether Træfik should handle it.
If the annotation is missing, contains an empty value, or the value
traefik, then the Træfik controller will take responsibility and process the associated Ingress object.
It is also possible to set the
ingressClass option in Træfik to a particular value. Træfik will only process matching Ingress objects.
For instance, setting the option to
traefik-internal causes Træfik to process Ingress objects with the same
kubernetes.io/ingress.class annotation value, ignoring all other objects (including those with a
traefik value, empty value, and missing annotation).
Letting multiple ingress controllers handle the same ingress objects can lead to unintended behavior.
It is recommended to prefix all ingressClass values with
traefik to avoid unintended collisions with other ingress implementations.
Between multiple Træfik Deployments¶
Sometimes multiple Træfik Deployments are supposed to run concurrently. For instance, it is conceivable to have one Deployment deal with internal and another one with external traffic.
For such cases, it is advisable to classify Ingress objects through a label and configure the
labelSelector option per each Træfik Deployment accordingly.
To stick with the internal/external example above, all Ingress objects meant for internal traffic could receive a
traffic-type: internal label while objects designated for external traffic receive a
traffic-type: external label.
The label selectors on the Træfik Deployments would then be
It is possible to split Ingress traffic in a fine-grained manner between multiple deployments using service weights.
One canonical use case is canary releases where a deployment representing a newer release is to receive an initially small but ever-increasing fraction of the requests over time. The way this can be done in Træfik is to specify a percentage of requests that should go into each deployment.
For instance, say that an application
my-app runs in version 1.
A newer version 2 is about to be released, but confidence in the robustness and reliability of new version running in production can only be gained gradually.
Thus, a new deployment
my-app-canary is created and scaled to a replica count that suffices for a 1% traffic share.
Along with it, a Service object is created as usual.
The Ingress specification would look like this:
apiVersion: extensions/v1beta1 kind: Ingress metadata: annotations: traefik.ingress.kubernetes.io/service-weights: | my-app: 99% my-app-canary: 1% name: my-app spec: rules: - http: paths: - backend: serviceName: my-app servicePort: 80 path: / - backend: serviceName: my-app-canary servicePort: 80 path: /
Take note of the
traefik.ingress.kubernetes.io/service-weights annotation: It specifies the distribution of requests among the referenced backend services,
With this definition, Træfik will route 99% of the requests to the pods backed by the
my-app deployment, and 1% to those backed by
Over time, the ratio may slowly shift towards the canary deployment until it is deemed to replace the previous main application, in steps such as 5%/95%, 10%/90%, 50%/50%, and finally 100%/0%.
A few conditions must hold for service weights to be applied correctly:
- The associated service backends must share the same path and host.
- The total percentage shared across all service backends must yield 100% (see the section on omitting the final service, however).
- The percentage values are interpreted as floating point numbers to a supported precision as defined in the annotation documentation.
Omitting the Final Service¶
When specifying service weights, it is possible to omit exactly one service for convenience reasons.
For instance, the following definition shows how to split requests in a scenario where a canary release is accompanied by a baseline deployment for easier metrics comparison or automated canary analysis:
apiVersion: extensions/v1beta1 kind: Ingress metadata: annotations: traefik.ingress.kubernetes.io/service-weights: | my-app-canary: 10% my-app-baseline: 10% name: app spec: rules: - http: paths: - backend: serviceName: my-app-canary servicePort: 80 path: / - backend: serviceName: my-app-baseline servicePort: 80 path: / - backend: serviceName: my-app-main servicePort: 80 path: /
This configuration assigns 80% of traffic to
my-app-main automatically, thus freeing the user from having to complete percentage values manually.
This becomes handy when increasing shares for canary releases continuously.
The examples shown deliberately do not specify any resource limitations as there is no one size fits all.
In a production environment, however, it is important to set proper bounds, especially with regards to CPU:
- too strict and Træfik will be throttled while serving requests (as Kubernetes imposes hard quotas)
- too loose and Træfik may waste resources not available for other containers
When in doubt, you should measure your resource needs, and adjust requests and limits accordingly.