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Traefik & Kubernetes

The Kubernetes Ingress Controller.

The Traefik Kubernetes Ingress provider is a Kubernetes Ingress controller; that is to say, it manages access to cluster services by supporting the Ingress specification.

Routing Configuration

See the dedicated section in routing.

Enabling and Using the Provider

As usual, the provider is enabled through the static configuration:

[providers.kubernetesIngress]
providers:
  kubernetesIngress: {}
--providers.kubernetesingress=true

The provider then watches for incoming ingresses events, such as the example below, and derives the corresponding dynamic configuration from it, which in turn will create the resulting routers, services, handlers, etc.

kind: Ingress
apiVersion: extensions/v1beta1
metadata:
  name: "foo"
  namespace: production

spec:
  rules:
    - host: example.net
      http:
        paths:
          - path: /bar
            backend:
              serviceName: service1
              servicePort: 80
          - path: /foo
            backend:
              serviceName: service1
              servicePort: 80

LetsEncrypt Support with the Ingress Provider

By design, Traefik is a stateless application, meaning that it only derives its configuration from the environment it runs in, without additional configuration. For this reason, users can run multiple instances of Traefik at the same time to achieve HA, as is a common pattern in the kubernetes ecosystem.

When using a single instance of Traefik with LetsEncrypt, no issues should be encountered, however this could be a single point of failure. Unfortunately, it is not possible to run multiple instances of Traefik 2.0 with LetsEncrypt enabled, because there is no way to ensure that the correct instance of Traefik will receive the challenge request, and subsequent responses. Previous versions of Traefik used a KV store to attempt to achieve this, but due to sub-optimal performance was dropped as a feature in 2.0.

If you require LetsEncrypt with HA in a kubernetes environment, we recommend using Traefik Enterprise where distributed LetsEncrypt is a supported feature.

If you are wanting to continue to run Traefik Community Edition, LetsEncrypt HA can be achieved by using a Certificate Controller such as Cert-Manager. When using Cert-Manager to manage certificates, it will create secrets in your namespaces that can be referenced as TLS secrets in your ingress objects.

Provider Configuration

endpoint

Optional, Default=empty

[providers.kubernetesIngress]
  endpoint = "http://localhost:8080"
  # ...
providers:
  kubernetesIngress:
    endpoint: "http://localhost:8080"
    # ...
--providers.kubernetesingress.endpoint=http://localhost:8080

The Kubernetes server endpoint as URL, which is only used when the behavior based on environment variables described below does not apply.

When deployed into Kubernetes, Traefik reads the environment variables KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT or KUBECONFIG to construct the endpoint.

The access token is looked up in /var/run/secrets/kubernetes.io/serviceaccount/token and the SSL CA certificate in /var/run/secrets/kubernetes.io/serviceaccount/ca.crt. They are both provided automatically as mounts in the pod where Traefik is deployed.

When the environment variables are not found, Traefik tries to connect to the Kubernetes API server with an external-cluster client. In which case, the endpoint is required. Specifically, it may be set to the URL used by kubectl proxy to connect to a Kubernetes cluster using the granted authentication and authorization of the associated kubeconfig.

token

Optional, Default=empty

[providers.kubernetesIngress]
  token = "mytoken"
  # ...
providers:
  kubernetesIngress:
    token: "mytoken"
    # ...
--providers.kubernetesingress.token=mytoken

Bearer token used for the Kubernetes client configuration.

certAuthFilePath

Optional, Default=empty

[providers.kubernetesIngress]
  certAuthFilePath = "/my/ca.crt"
  # ...
providers:
  kubernetesIngress:
    certAuthFilePath: "/my/ca.crt"
    # ...
--providers.kubernetesingress.certauthfilepath=/my/ca.crt

Path to the certificate authority file. Used for the Kubernetes client configuration.

disablePassHostHeaders

Optional, Default=false

[providers.kubernetesIngress]
  disablePassHostHeaders = true
  # ...
providers:
  kubernetesIngress:
    disablePassHostHeaders: true
    # ...
--providers.kubernetesingress.disablepasshostheaders=true

Whether to disable PassHost Headers.

namespaces

Optional, Default: all namespaces (empty array)

[providers.kubernetesIngress]
  namespaces = ["default", "production"]
  # ...
providers:
  kubernetesIngress:
    namespaces:
      - "default"
      - "production"
    # ...
--providers.kubernetesingress.namespaces=default,production

Array of namespaces to watch.

labelSelector

Optional,Default: empty (process all Ingresses)

[providers.kubernetesIngress]
  labelSelector = "app=traefik"
  # ...
providers:
  kubernetesIngress:
    labelselector: "app=traefik"
    # ...
--providers.kubernetesingress.labelselector="app=traefik"

By default, Traefik processes all Ingress objects in the configured namespaces. A label selector can be defined to filter on specific Ingress objects only.

See label-selectors for details.

ingressClass

Optional, Default: empty

[providers.kubernetesIngress]
  ingressClass = "traefik-internal"
  # ...
providers:
  kubernetesIngress:
    ingressClass: "traefik-internal"
    # ...
--providers.kubernetesingress.ingressclass=traefik-internal

Value of kubernetes.io/ingress.class annotation that identifies Ingress objects to be processed.

If the parameter is non-empty, only Ingresses containing an annotation with the same value are processed. Otherwise, Ingresses missing the annotation, having an empty value, or with the value traefik are processed.

Kubernetes 1.18+

If the Kubernetes cluster version is 1.18+, the new IngressClass resource can be leveraged to identify Ingress objects that should be processed. In that case, Traefik will look for an IngressClass in the cluster with the controller value equal to traefik.io/ingress-controller.

Please see this article for more information or the example below.

apiVersion: networking.k8s.io/v1beta1
kind: IngressClass
metadata: 
  name: traefik-lb
spec: 
  controller: traefik.io/ingress-controller
apiVersion: "networking.k8s.io/v1beta1"
kind: "Ingress"
metadata:
  name: "example-ingress"
spec:
  ingressClassName: "traefik-lb"
  rules:
  - host: "*.example.com"
    http:
      paths:
      - path: "/example"
        backend:
          serviceName: "example-service"
          servicePort: 80

ingressEndpoint

hostname

Optional, Default: empty

[providers.kubernetesIngress.ingressEndpoint]
  hostname = "example.net"
  # ...
providers:
  kubernetesIngress:
    ingressEndpoint:
      hostname: "example.net"
    # ...
--providers.kubernetesingress.ingressendpoint.hostname=example.net

Hostname used for Kubernetes Ingress endpoints.

ip

Optional, Default: empty

[providers.kubernetesIngress.ingressEndpoint]
  ip = "1.2.3.4"
  # ...
providers:
  kubernetesIngress:
    ingressEndpoint:
      ip: "1.2.3.4"
    # ...
--providers.kubernetesingress.ingressendpoint.ip=1.2.3.4

IP used for Kubernetes Ingress endpoints.

publishedService

Optional, Default: empty

[providers.kubernetesIngress.ingressEndpoint]
  publishedService = "namespace/foo-service"
  # ...
providers:
  kubernetesIngress:
    ingressEndpoint:
      publishedService: "namespace/foo-service"
    # ...
--providers.kubernetesingress.ingressendpoint.publishedservice=namespace/foo-service

Published Kubernetes Service to copy status from. Format: namespace/servicename.

throttleDuration

Optional, Default: 0 (no throttling)

[providers.kubernetesIngress]
  throttleDuration = "10s"
  # ...
providers:
  kubernetesIngress:
    throttleDuration: "10s"
    # ...
--providers.kubernetesingress.throttleDuration=10s

Further

If one wants to know more about the various aspects of the Ingress spec that Traefik supports, many examples of Ingresses definitions are located in the tests data of the Traefik repository.