27 KiB
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
Prerequisites
- 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.
!!! note The guide is likely not fully adequate for a production-ready setup.
- The
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.
!!! note 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
examples/k8s/traefik-rbac.yaml
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 kubernetes.namespaces parameter.
Deploy Træfik using a Deployment or DaemonSet
It is possible to use Træfik with a Deployment or a DaemonSet object, whereas both options have their own pros and cons:
- 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
examples/k8s/traefik-deployment.yaml
!!! note 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
!!! note
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:
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 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 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.
!!! note
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 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 $(minikube ip):<NODEPORT>
404 page not found
!!! note We expect to see a 404 response here as we haven't yet given Træfik any configuration.
All further examples below assume a DaemonSet installation. Deployment users will need to append the NodePort when constructing requests.
Deploy Træfik using Helm Chart
!!! note The Helm Chart is maintained by the community, not the Træfik project maintainers.
Instead of installing Træfik via Kubernetes object directly, you can also use the Træfik Helm chart.
Install the Træfik chart by:
helm install stable/traefik
Install the Træfik chart using a values.yaml file.
helm install --values values.yaml stable/traefik
dashboard:
enabled: true
domain: traefik-ui.minikube
kubernetes:
namespaces:
- default
- kube-system
For more information, check out the documentation.
Submitting an Ingress to the Cluster
Lets start by creating a Service and an Ingress that will expose the Træfik Web UI.
apiVersion: v1
kind: Service
metadata:
name: traefik-web-ui
namespace: kube-system
spec:
selector:
k8s-app: traefik-ingress-lb
ports:
- port: 80
targetPort: 8080
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: traefik-web-ui
namespace: kube-system
annotations:
kubernetes.io/ingress.class: traefik
spec:
rules:
- host: traefik-ui.minikube
http:
paths:
- backend:
serviceName: traefik-web-ui
servicePort: 80
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/ui.yaml
Now lets setup an entry in our /etc/hosts file to route traefik-ui.minikube to our cluster.
In production you would want to set up real DNS entries.
You can get the IP address of your minikube instance by running minikube ip:
echo "$(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
!!! note 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.
!!! note
The secret must have two entries named tls.keyand tls.crt.
See the Kubernetes documentation for more details.
!!! note
The TLS certificates will be added to all entrypoints defined by the ingress annotation traefik.frontend.entryPoints.
If no such annotation is provided, the TLS certificates will be added to all TLS-enabled defaultEntryPoints.
!!! note
The field 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.
Basic Authentication
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
A. Use 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:
cat auth
myusername:$apr1$78Jyn/1K$ERHKVRPPlzAX8eBtLuvRZ0
B. Now use kubectl to create a secret in the monitoring namespace using the file created by htpasswd.
kubectl create secret generic mysecret --from-file auth --namespace=monitoring
!!! note Secret must be in same namespace as the Ingress object.
C. Attach the following annotations to the Ingress object:
ingress.kubernetes.io/auth-type: "basic"ingress.kubernetes.io/auth-secret: "mysecret"
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
ingress.kubernetes.io/auth-type: "basic"
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
Name-based Routing
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
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
!!! note
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.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
!!! note 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 "$(minikube ip) stilton.minikube cheddar.minikube wensleydale.minikube" | sudo tee -a /etc/hosts
Path-based Routing
Now lets suppose that our fictional client has decided that while they are super happy about our cheesy web design, when they asked for 3 websites they had not really bargained on having to buy 3 domain names.
No problem, we say, why don't we reconfigure the sites to host all 3 under one domain.
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: cheeses
annotations:
kubernetes.io/ingress.class: traefik
traefik.frontend.rule.type: PathPrefixStrip
spec:
rules:
- host: cheeses.minikube
http:
paths:
- path: /stilton
backend:
serviceName: stilton
servicePort: http
- path: /cheddar
backend:
serviceName: cheddar
servicePort: http
- path: /wensleydale
backend:
serviceName: wensleydale
servicePort: http
examples/k8s/cheeses-ingress.yaml
!!! note
We are configuring Træfik to strip the prefix from the url path with the traefik.frontend.rule.type annotation so that we can use the containers from the previous example without modification.
kubectl apply -f https://raw.githubusercontent.com/containous/traefik/master/examples/k8s/cheeses-ingress.yaml
echo "$(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.
Disable globally
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 "false".
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/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.
Production advice
Resource limitations
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.