973 lines
30 KiB
Markdown
973 lines
30 KiB
Markdown
# Kubernetes Ingress Controller
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This guide explains how to use Træfik as an Ingress controller for a Kubernetes cluster.
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If you are not familiar with Ingresses in Kubernetes you might want to read the [Kubernetes user guide](https://kubernetes.io/docs/concepts/services-networking/ingress/)
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The config files used in this guide can be found in the [examples directory](https://github.com/containous/traefik/tree/master/examples/k8s)
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## Prerequisites
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1. A working Kubernetes cluster. If you want to follow along with this guide, you should setup [minikube](https://kubernetes.io/docs/getting-started-guides/minikube/) on your machine, as it is the quickest way to get a local Kubernetes cluster setup for experimentation and development.
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!!! note
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The guide is likely not fully adequate for a production-ready setup.
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2. The `kubectl` binary should be [installed on your workstation](https://kubernetes.io/docs/getting-started-guides/minikube/#download-kubectl).
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### Role Based Access Control configuration (Kubernetes 1.6+ only)
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Kubernetes introduces [Role Based Access Control (RBAC)](https://kubernetes.io/docs/reference/access-authn-authz/rbac/) in 1.6+ to allow fine-grained control of Kubernetes resources and API.
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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.
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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.
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!!! note
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RoleBindings per namespace are available in Træfik 1.5 and later. Please use ClusterRoleBindings for older versions.
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For the sake of simplicity, this guide will use a ClusterRoleBinding:
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```yaml
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---
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kind: ClusterRole
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apiVersion: rbac.authorization.k8s.io/v1beta1
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metadata:
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name: traefik-ingress-controller
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rules:
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- apiGroups:
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- ""
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resources:
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- services
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- endpoints
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- secrets
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verbs:
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- get
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- list
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- watch
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- apiGroups:
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- extensions
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resources:
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- ingresses
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verbs:
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- get
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- list
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- watch
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---
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kind: ClusterRoleBinding
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apiVersion: rbac.authorization.k8s.io/v1beta1
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metadata:
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name: traefik-ingress-controller
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roleRef:
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apiGroup: rbac.authorization.k8s.io
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kind: ClusterRole
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name: traefik-ingress-controller
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subjects:
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- kind: ServiceAccount
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name: traefik-ingress-controller
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namespace: kube-system
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```
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[examples/k8s/traefik-rbac.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/traefik-rbac.yaml)
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```shell
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kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-rbac.yaml
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```
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For namespaced restrictions, one RoleBinding is required per watched namespace along with a corresponding configuration of Træfik's `kubernetes.namespaces` parameter.
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## Deploy Træfik using a Deployment or DaemonSet
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It is possible to use Træfik with a [Deployment](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/) or a [DaemonSet](https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/) object,
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whereas both options have their own pros and cons:
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- 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.
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- DaemonSets automatically scale to new nodes, when the nodes join the cluster, whereas Deployment pods are only scheduled on new nodes if required.
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- 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.
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- DaemonSets can be run with the `NET_BIND_SERVICE` capability, 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](https://kubernetes.io/docs/concepts/configuration/overview/#services), and raises the potential for scheduling/scaling issues. Despite potential issues, this remains the choice for most ingress controllers.
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- If you are unsure which to choose, start with the Daemonset.
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The Deployment objects looks like this:
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```yaml
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---
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: traefik-ingress-controller
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namespace: kube-system
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---
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kind: Deployment
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apiVersion: extensions/v1beta1
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metadata:
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name: traefik-ingress-controller
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namespace: kube-system
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labels:
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k8s-app: traefik-ingress-lb
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spec:
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replicas: 1
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selector:
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matchLabels:
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k8s-app: traefik-ingress-lb
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template:
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metadata:
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labels:
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k8s-app: traefik-ingress-lb
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name: traefik-ingress-lb
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spec:
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serviceAccountName: traefik-ingress-controller
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terminationGracePeriodSeconds: 60
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containers:
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- image: traefik
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name: traefik-ingress-lb
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ports:
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- name: http
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containerPort: 80
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- name: admin
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containerPort: 8080
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args:
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- --api
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- --kubernetes
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- --logLevel=INFO
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---
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kind: Service
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apiVersion: v1
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metadata:
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name: traefik-ingress-service
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namespace: kube-system
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spec:
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selector:
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k8s-app: traefik-ingress-lb
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ports:
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- protocol: TCP
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port: 80
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name: web
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- protocol: TCP
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port: 8080
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name: admin
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type: NodePort
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```
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[examples/k8s/traefik-deployment.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/traefik-deployment.yaml)
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!!! note
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The Service will expose two NodePorts which allow access to the ingress and the web interface.
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The DaemonSet objects looks not much different:
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```yaml
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---
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: traefik-ingress-controller
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namespace: kube-system
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---
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kind: DaemonSet
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apiVersion: extensions/v1beta1
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metadata:
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name: traefik-ingress-controller
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namespace: kube-system
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labels:
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k8s-app: traefik-ingress-lb
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spec:
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template:
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metadata:
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labels:
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k8s-app: traefik-ingress-lb
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name: traefik-ingress-lb
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spec:
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serviceAccountName: traefik-ingress-controller
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terminationGracePeriodSeconds: 60
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containers:
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- image: traefik
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name: traefik-ingress-lb
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ports:
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- name: http
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containerPort: 80
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hostPort: 80
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- name: admin
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containerPort: 8080
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securityContext:
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capabilities:
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drop:
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- ALL
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add:
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- NET_BIND_SERVICE
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args:
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- --api
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- --kubernetes
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- --logLevel=INFO
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---
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kind: Service
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apiVersion: v1
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metadata:
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name: traefik-ingress-service
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namespace: kube-system
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spec:
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selector:
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k8s-app: traefik-ingress-lb
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ports:
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- protocol: TCP
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port: 80
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name: web
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- protocol: TCP
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port: 8080
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name: admin
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```
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[examples/k8s/traefik-ds.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/traefik-ds.yaml)
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!!! note
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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.
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To deploy Træfik to your cluster start by submitting one of the YAML files to the cluster with `kubectl`:
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```shell
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kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-deployment.yaml
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```
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```shell
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kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/traefik-ds.yaml
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```
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There are some significant differences between using Deployments and DaemonSets:
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- The Deployment has easier up and down scaling possibilities.
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It can implement full pod lifecycle and supports rolling updates from Kubernetes 1.2.
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At least one Pod is needed to run the Deployment.
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- The DaemonSet automatically scales to all nodes that meets a specific selector and guarantees to fill nodes one at a time.
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Rolling updates are fully supported from Kubernetes 1.7 for DaemonSets as well.
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### Check the Pods
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Now lets check if our command was successful.
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Start by listing the pods in the `kube-system` namespace:
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```shell
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kubectl --namespace=kube-system get pods
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```
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```shell
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NAME READY STATUS RESTARTS AGE
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kube-addon-manager-minikubevm 1/1 Running 0 4h
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kubernetes-dashboard-s8krj 1/1 Running 0 4h
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traefik-ingress-controller-678226159-eqseo 1/1 Running 0 7m
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```
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You should see that after submitting the Deployment or DaemonSet to Kubernetes it has launched a Pod, and it is now running.
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_It might take a few moments for Kubernetes to pull the Træfik image and start the container._
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!!! note
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You could also check the deployment with the Kubernetes dashboard, run
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`minikube dashboard` to open it in your browser, then choose the `kube-system`
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namespace from the menu at the top right of the screen.
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You should now be able to access Træfik on port 80 of your Minikube instance when using the DaemonSet:
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```shell
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curl $(minikube ip)
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```
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```shell
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404 page not found
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```
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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`.
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```shell
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curl $(minikube ip):<NODEPORT>
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```
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```shell
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404 page not found
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```
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!!! note
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We expect to see a 404 response here as we haven't yet given Træfik any configuration.
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All further examples below assume a DaemonSet installation. Deployment users will need to append the NodePort when constructing requests.
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## Deploy Træfik using Helm Chart
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!!! note
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The Helm Chart is maintained by the community, not the Træfik project maintainers.
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Instead of installing Træfik via Kubernetes object directly, you can also use the Træfik Helm chart.
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Install the Træfik chart by:
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```shell
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helm install stable/traefik
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```
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Install the Træfik chart using a values.yaml file.
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```shell
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helm install --values values.yaml stable/traefik
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```
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```yaml
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dashboard:
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enabled: true
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domain: traefik-ui.minikube
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kubernetes:
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namespaces:
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- default
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- kube-system
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```
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For more information, check out [the documentation](https://github.com/kubernetes/charts/tree/master/stable/traefik).
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## Submitting an Ingress to the Cluster
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Lets start by creating a Service and an Ingress that will expose the [Træfik Web UI](https://github.com/containous/traefik#web-ui).
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: traefik-web-ui
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namespace: kube-system
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spec:
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selector:
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k8s-app: traefik-ingress-lb
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ports:
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- name: web
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port: 80
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targetPort: 8080
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---
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apiVersion: extensions/v1beta1
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kind: Ingress
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metadata:
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name: traefik-web-ui
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namespace: kube-system
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spec:
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rules:
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- host: traefik-ui.minikube
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http:
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paths:
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- path: /
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backend:
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serviceName: traefik-web-ui
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servicePort: web
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```
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[examples/k8s/ui.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/ui.yaml)
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```shell
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kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/ui.yaml
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```
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Now lets setup an entry in our `/etc/hosts` file to route `traefik-ui.minikube` to our cluster.
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In production you would want to set up real DNS entries.
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You can get the IP address of your minikube instance by running `minikube ip`:
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```shell
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echo "$(minikube ip) traefik-ui.minikube" | sudo tee -a /etc/hosts
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```
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We should now be able to visit [traefik-ui.minikube](http://traefik-ui.minikube) in the browser and view the Træfik web UI.
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### Add a TLS Certificate to the Ingress
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!!! note
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For this example to work you need a TLS entrypoint. You don't have to provide a TLS certificate at this point.
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For more details see [here](/configuration/entrypoints/).
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To setup an HTTPS-protected ingress, you can leverage the TLS feature of the ingress resource.
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```yaml
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apiVersion: extensions/v1beta1
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kind: Ingress
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metadata:
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name: traefik-web-ui
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namespace: kube-system
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annotations:
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kubernetes.io/ingress.class: traefik
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spec:
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rules:
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- host: traefik-ui.minikube
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http:
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paths:
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- backend:
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serviceName: traefik-web-ui
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servicePort: 80
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tls:
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- secretName: traefik-ui-tls-cert
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```
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In addition to the modified ingress you need to provide the TLS certificate via a Kubernetes secret in the same namespace as the ingress.
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The following two commands will generate a new certificate and create a secret containing the key and cert files.
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```shell
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openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=traefik-ui.minikube"
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kubectl -n kube-system create secret tls traefik-ui-tls-cert --key=tls.key --cert=tls.crt
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```
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If there are any errors while loading the TLS section of an ingress, the whole ingress will be skipped.
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!!! note
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The secret must have two entries named `tls.key`and `tls.crt`.
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See the [Kubernetes documentation](https://kubernetes.io/docs/concepts/services-networking/ingress/#tls) for more details.
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!!! note
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The TLS certificates will be added to all entrypoints defined by the ingress annotation `traefik.frontend.entryPoints`.
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If no such annotation is provided, the TLS certificates will be added to all TLS-enabled `defaultEntryPoints`.
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!!! note
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The field `hosts` in the TLS configuration is ignored. Instead, the domains provided by the certificate are used for this purpose.
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It is recommended to not use wildcard certificates as they will match globally.
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## Basic Authentication
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It's possible to protect access to Træfik through basic authentication. (See the [Kubernetes Ingress](/configuration/backends/kubernetes) configuration page for syntactical details and restrictions.)
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### Creating the Secret
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A. Use `htpasswd` to create a file containing the username and the MD5-encoded password:
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```shell
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htpasswd -c ./auth myusername
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```
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You will be prompted for a password which you will have to enter twice.
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`htpasswd` will create a file with the following:
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```shell
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cat auth
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```
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```shell
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myusername:$apr1$78Jyn/1K$ERHKVRPPlzAX8eBtLuvRZ0
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```
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B. Now use `kubectl` to create a secret in the `monitoring` namespace using the file created by `htpasswd`.
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```shell
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kubectl create secret generic mysecret --from-file auth --namespace=monitoring
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```
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!!! note
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Secret must be in same namespace as the Ingress object.
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C. Attach the following annotations to the Ingress object:
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- `ingress.kubernetes.io/auth-type: "basic"`
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- `ingress.kubernetes.io/auth-secret: "mysecret"`
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They specify basic authentication and reference the Secret `mysecret` containing the credentials.
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Following is a full Ingress example based on Prometheus:
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```yaml
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apiVersion: extensions/v1beta1
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kind: Ingress
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metadata:
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name: prometheus-dashboard
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namespace: monitoring
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annotations:
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kubernetes.io/ingress.class: traefik
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ingress.kubernetes.io/auth-type: "basic"
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ingress.kubernetes.io/auth-secret: "mysecret"
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spec:
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rules:
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- host: dashboard.prometheus.example.com
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http:
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paths:
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- backend:
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serviceName: prometheus
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servicePort: 9090
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```
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You can apply the example as following:
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```shell
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kubectl create -f prometheus-ingress.yaml -n monitoring
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```
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## Name-based Routing
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In this example we are going to setup websites for three of the United Kingdoms best loved cheeses: Cheddar, Stilton, and Wensleydale.
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First lets start by launching the pods for the cheese websites.
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```yaml
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---
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kind: Deployment
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apiVersion: extensions/v1beta1
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metadata:
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name: stilton
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labels:
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app: cheese
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cheese: stilton
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spec:
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replicas: 2
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selector:
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matchLabels:
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app: cheese
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task: stilton
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template:
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metadata:
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labels:
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app: cheese
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task: stilton
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version: v0.0.1
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spec:
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containers:
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- name: cheese
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image: errm/cheese:stilton
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ports:
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- containerPort: 80
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---
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kind: Deployment
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apiVersion: extensions/v1beta1
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metadata:
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name: cheddar
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labels:
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app: cheese
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cheese: cheddar
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spec:
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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
|
|
```
|
|
|
|
[examples/k8s/cheese-deployments.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/cheese-deployments.yaml)
|
|
|
|
```shell
|
|
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.
|
|
|
|
```yaml
|
|
---
|
|
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
|
|
```
|
|
|
|
!!! note
|
|
We also set a [circuit breaker expression](/basics/#backends) for one of the backends by setting the `traefik.backend.circuitbreaker` annotation on the service.
|
|
|
|
[examples/k8s/cheese-services.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/cheese-services.yaml)
|
|
|
|
```shell
|
|
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.
|
|
|
|
```yaml
|
|
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
|
|
```
|
|
|
|
[examples/k8s/cheese-ingress.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/cheese-ingress.yaml)
|
|
|
|
!!! note
|
|
we list each hostname, and add a backend service.
|
|
|
|
```shell
|
|
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheese-ingress.yaml
|
|
```
|
|
|
|
Now visit the [Træfik dashboard](http://traefik-ui.minikube/) 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.
|
|
|
|
```shell
|
|
echo "$(minikube ip) stilton.minikube cheddar.minikube wensleydale.minikube" | sudo tee -a /etc/hosts
|
|
```
|
|
|
|
- [Stilton](http://stilton.minikube/)
|
|
- [Cheddar](http://cheddar.minikube/)
|
|
- [Wensleydale](http://wensleydale.minikube/)
|
|
|
|
## Path-based Routing
|
|
|
|
Now lets suppose that our fictional client has decided that while they are super happy about our cheesy web design, when they asked for 3 websites they had not really bargained on having to buy 3 domain names.
|
|
|
|
No problem, we say, why don't we reconfigure the sites to host all 3 under one domain.
|
|
|
|
```yaml
|
|
apiVersion: extensions/v1beta1
|
|
kind: Ingress
|
|
metadata:
|
|
name: cheeses
|
|
annotations:
|
|
kubernetes.io/ingress.class: traefik
|
|
traefik.frontend.rule.type: PathPrefixStrip
|
|
spec:
|
|
rules:
|
|
- host: cheeses.minikube
|
|
http:
|
|
paths:
|
|
- path: /stilton
|
|
backend:
|
|
serviceName: stilton
|
|
servicePort: http
|
|
- path: /cheddar
|
|
backend:
|
|
serviceName: cheddar
|
|
servicePort: http
|
|
- path: /wensleydale
|
|
backend:
|
|
serviceName: wensleydale
|
|
servicePort: http
|
|
```
|
|
|
|
[examples/k8s/cheeses-ingress.yaml](https://github.com/containous/traefik/tree/master/examples/k8s/cheeses-ingress.yaml)
|
|
|
|
!!! note
|
|
We are configuring Træfik to strip the prefix from the url path with the `traefik.frontend.rule.type` annotation so that we can use the containers from the previous example without modification.
|
|
|
|
```shell
|
|
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheeses-ingress.yaml
|
|
```
|
|
|
|
```shell
|
|
echo "$(minikube ip) cheeses.minikube" | sudo tee -a /etc/hosts
|
|
```
|
|
|
|
You should now be able to visit the websites in your browser.
|
|
|
|
- [cheeses.minikube/stilton](http://cheeses.minikube/stilton/)
|
|
- [cheeses.minikube/cheddar](http://cheeses.minikube/cheddar/)
|
|
- [cheeses.minikube/wensleydale](http://cheeses.minikube/wensleydale/)
|
|
|
|
## 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.:
|
|
|
|
```yaml
|
|
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](https://kubernetes.io/docs/concepts/services-networking/service/#services-without-selectors),
|
|
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.
|
|
|
|
### Disable globally
|
|
|
|
Add the following to your TOML configuration file:
|
|
|
|
```toml
|
|
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 definition:
|
|
|
|
```yaml
|
|
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:
|
|
|
|
```yaml
|
|
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/static`, and `static.otherdomain.com` would receive the request with the Host header being `static.otherdomain.com`.
|
|
|
|
!!! note
|
|
The per-ingress annotation overrides whatever the global value is set to.
|
|
So you could set `disablePassHostHeaders` to `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.
|
|
|
|
The `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).
|
|
|
|
!!! note
|
|
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 `traffic-type=internal` and `traffic-type=external`, respectively.
|
|
|
|
## Traffic Splitting
|
|
|
|
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:
|
|
|
|
```yaml
|
|
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, `my-app` and `my-app-canary`.
|
|
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 `my-app-canary`.
|
|
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](#omitting-the-final-service), however).
|
|
- The percentage values are interpreted as floating point numbers to a supported precision as defined in the [annotation documentation](/configuration/backends/kubernetes#general-annotations).
|
|
|
|
### 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:
|
|
|
|
```yaml
|
|
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.
|
|
|
|
## Production advice
|
|
|
|
### Resource limitations
|
|
|
|
The examples shown deliberately do not specify any [resource limitations](https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/) 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.
|