Create an ingress controller in Azure Kubernetes Service (AKS)

An ingress controller is a piece of software that provides reverse proxy, configurable traffic routing, and TLS termination for Kubernetes services. Kubernetes ingress resources are used to configure the ingress rules and routes for individual Kubernetes services. Using an ingress controller and ingress rules, a single IP address can be used to route traffic to multiple services in a Kubernetes cluster.

This article shows you how to deploy the NGINX ingress controller in an Azure Kubernetes Service (AKS) cluster. Two applications are then run in the AKS cluster, each of which is accessible over the single IP address.

Alternatively, you can also:

• Enable the HTTP application routing add-on
• Create an ingress controller that uses an internal, private network and IP address
• Create an ingress controller that uses your own TLS certificates
• Create an ingress controller that uses Let's Encrypt to automatically generate TLS certificates with a dynamic public IP address or with a static public IP address

Before you begin

This article uses Helm 3 to install the NGINX ingress controller on a supported version of Kubernetes. Make sure that you are using the latest release of Helm and have access to the ingress-nginx Helm repository. The steps outlined in this article may not be compatible with previous versions of the Helm chart, NGINX ingress controller, or Kubernetes.

This article also requires that you are running the Azure CLI version 2.0.64 or later. Run az --version to find the version. If you need to install or upgrade, see Install Azure CLI.

In addition, this article assumes you have an existing AKS cluster with an integrated ACR. For more details on creating an AKS cluster with an integrated ACR, see Authenticate with Azure Container Registry from Azure Kubernetes Service.

Basic configuration

To create a simple NGINX ingress controller without customizing the defaults, you will use helm.

NAMESPACE=ingress-basic

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update

helm install ingress-nginx ingress-nginx/ingress-nginx --create-namespace --namespace $NAMESPACE 

Note that the above configuration uses the 'out of the box' configuration for simplicity. If needed, you could add parameters for customizing the deployment, eg, --set controller.replicaCount=3. The next section will show a highly customized example of the ingress controller.

Customized configuration

As an alternative to the basic configuration presented in the above section, the next set of steps will show how to deploy a customized ingress controller.

Import the images used by the Helm chart into your ACR

To control image versions, you will want to import them into your own Azure Container registry. The NGINX ingress controller Helm chart relies on three container images. Use az acr import to import those images into your ACR.

REGISTRY_NAME=<REGISTRY_NAME>
SOURCE_REGISTRY=k8s.gcr.io
CONTROLLER_IMAGE=ingress-nginx/controller
CONTROLLER_TAG=v1.0.4
PATCH_IMAGE=ingress-nginx/kube-webhook-certgen
PATCH_TAG=v1.1.1
DEFAULTBACKEND_IMAGE=defaultbackend-amd64
DEFAULTBACKEND_TAG=1.5

az acr import --name $REGISTRY_NAME --source $SOURCE_REGISTRY/$CONTROLLER_IMAGE:$CONTROLLER_TAG --image $CONTROLLER_IMAGE:$CONTROLLER_TAG
az acr import --name $REGISTRY_NAME --source $SOURCE_REGISTRY/$PATCH_IMAGE:$PATCH_TAG --image $PATCH_IMAGE:$PATCH_TAG
az acr import --name $REGISTRY_NAME --source $SOURCE_REGISTRY/$DEFAULTBACKEND_IMAGE:$DEFAULTBACKEND_TAG --image $DEFAULTBACKEND_IMAGE:$DEFAULTBACKEND_TAG

Create an ingress controller

To create the ingress controller, use Helm to install nginx-ingress. For added redundancy, two replicas of the NGINX ingress controllers are deployed with the --set controller.replicaCount parameter. To fully benefit from running replicas of the ingress controller, make sure there's more than one node in your AKS cluster.

The ingress controller also needs to be scheduled on a Linux node. Windows Server nodes shouldn't run the ingress controller. A node selector is specified using the --set nodeSelector parameter to tell the Kubernetes scheduler to run the NGINX ingress controller on a Linux-based node.

# Add the ingress-nginx repository
helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx

# Set variable for ACR location to use for pulling images
ACR_URL=<REGISTRY_URL>

# Use Helm to deploy an NGINX ingress controller
helm install nginx-ingress ingress-nginx/ingress-nginx \
    --namespace ingress-basic --create-namespace \
    --set controller.replicaCount=2 \
    --set controller.nodeSelector."kubernetes\.io/os"=linux \
    --set controller.image.registry=$ACR_URL \
    --set controller.image.image=$CONTROLLER_IMAGE \
    --set controller.image.tag=$CONTROLLER_TAG \
    --set controller.image.digest="" \
    --set controller.admissionWebhooks.patch.nodeSelector."kubernetes\.io/os"=linux \
    --set controller.admissionWebhooks.patch.image.registry=$ACR_URL \
    --set controller.admissionWebhooks.patch.image.image=$PATCH_IMAGE \
    --set controller.admissionWebhooks.patch.image.tag=$PATCH_TAG \
    --set controller.admissionWebhooks.patch.image.digest="" \
    --set defaultBackend.nodeSelector."kubernetes\.io/os"=linux \
    --set defaultBackend.image.registry=$ACR_URL \
    --set defaultBackend.image.image=$DEFAULTBACKEND_IMAGE \
    --set defaultBackend.image.tag=$DEFAULTBACKEND_TAG \
    --set defaultBackend.image.digest=""

Check the load balancer service

When the Kubernetes load balancer service is created for the NGINX ingress controller, a dynamic public IP address is assigned, as shown in the following example output:

$ kubectl --namespace ingress-basic get services -o wide -w nginx-ingress-ingress-nginx-controller

NAME                                     TYPE           CLUSTER-IP    EXTERNAL-IP     PORT(S)                      AGE   SELECTOR
nginx-ingress-ingress-nginx-controller   LoadBalancer   10.0.74.133   EXTERNAL_IP     80:32486/TCP,443:30953/TCP   44s   app.kubernetes.io/component=controller,app.kubernetes.io/instance=nginx-ingress,app.kubernetes.io/name=ingress-nginx

No ingress rules have been created yet, so the NGINX ingress controller's default 404 page is displayed if you browse to the external IP address. Ingress rules are configured in the following steps.

Run demo applications

To see the ingress controller in action, run two demo applications in your AKS cluster. In this example, you use kubectl apply to deploy two instances of a simple Hello world application.

Create a aks-helloworld-one.yaml file and copy in the following example YAML:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: aks-helloworld-one  
spec:
  replicas: 1
  selector:
    matchLabels:
      app: aks-helloworld-one
  template:
    metadata:
      labels:
        app: aks-helloworld-one
    spec:
      containers:
      - name: aks-helloworld-one
        image: mcr.microsoft.com/azuredocs/aks-helloworld:v1
        ports:
        - containerPort: 80
        env:
        - name: TITLE
          value: "Welcome to Azure Kubernetes Service (AKS)"
---
apiVersion: v1
kind: Service
metadata:
  name: aks-helloworld-one  
spec:
  type: ClusterIP
  ports:
  - port: 80
  selector:
    app: aks-helloworld-one

Create a aks-helloworld-two.yaml file and copy in the following example YAML:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: aks-helloworld-two  
spec:
  replicas: 1
  selector:
    matchLabels:
      app: aks-helloworld-two
  template:
    metadata:
      labels:
        app: aks-helloworld-two
    spec:
      containers:
      - name: aks-helloworld-two
        image: mcr.microsoft.com/azuredocs/aks-helloworld:v1
        ports:
        - containerPort: 80
        env:
        - name: TITLE
          value: "AKS Ingress Demo"
---
apiVersion: v1
kind: Service
metadata:
  name: aks-helloworld-two  
spec:
  type: ClusterIP
  ports:
  - port: 80
  selector:
    app: aks-helloworld-two

Run the two demo applications using kubectl apply:

kubectl apply -f aks-helloworld-one.yaml --namespace ingress-basic
kubectl apply -f aks-helloworld-two.yaml --namespace ingress-basic

Create an ingress route

Both applications are now running on your Kubernetes cluster. To route traffic to each application, create a Kubernetes ingress resource. The ingress resource configures the rules that route traffic to one of the two applications.

In the following example, traffic to EXTERNAL_IP is routed to the service named aks-helloworld-one. Traffic to EXTERNAL_IP/hello-world-two is routed to the aks-helloworld-two service. Traffic to EXTERNAL_IP/static is routed to the service named aks-helloworld-one for static assets.

Create a file named hello-world-ingress.yaml and copy in the following example YAML.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-world-ingress
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
    nginx.ingress.kubernetes.io/use-regex: "true"
    nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
  rules:
  - http:
      paths:
      - path: /hello-world-one(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld-one
            port:
              number: 80
      - path: /hello-world-two(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld-two
            port:
              number: 80
      - path: /(.*)
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld-one
            port:
              number: 80
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-world-ingress-static
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
    nginx.ingress.kubernetes.io/rewrite-target: /static/$2
spec:
  rules:
  - http:
      paths:
      - path:
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld-one
            port: 
              number: 80
        path: /static(/|$)(.*)

Create the ingress resource using the kubectl apply -f hello-world-ingress.yaml command.

$ kubectl apply -f hello-world-ingress.yaml --namespace ingress-basic

ingress.extensions/hello-world-ingress created
ingress.extensions/hello-world-ingress-static created

Test the ingress controller

To test the routes for the ingress controller, browse to the two applications. Open a web browser to the IP address of your NGINX ingress controller, such as EXTERNAL_IP. The first demo application is displayed in the web browser, as shown in the follow example:

Now add the /hello-world-two path to the IP address, such as EXTERNAL_IP/hello-world-two. The second demo application with the custom title is displayed:

Clean up resources

This article used Helm to install the ingress components and sample apps. When you deploy a Helm chart, a number of Kubernetes resources are created. These resources includes pods, deployments, and services. To clean up these resources, you can either delete the entire sample namespace, or the individual resources.

Delete the sample namespace and all resources

To delete the entire sample namespace, use the kubectl delete command and specify your namespace name. All the resources in the namespace are deleted.

kubectl delete namespace ingress-basic

Delete resources individually

Alternatively, a more granular approach is to delete the individual resources created. List the Helm releases with the helm list command. Look for charts named nginx-ingress and aks-helloworld, as shown in the following example output:

$ helm list --namespace ingress-basic

NAME                    NAMESPACE       REVISION        UPDATED                                 STATUS          CHART                   APP VERSION
nginx-ingress           ingress-basic   1               2020-01-06 19:55:46.358275 -0600 CST    deployed        nginx-ingress-1.27.1    0.26.1  

Uninstall the releases with the helm uninstall command. The following example uninstalls the NGINX ingress deployment.

$ helm uninstall nginx-ingress --namespace ingress-basic

release "nginx-ingress" uninstalled

Next, remove the two sample applications:

kubectl delete -f aks-helloworld-one.yaml --namespace ingress-basic
kubectl delete -f aks-helloworld-two.yaml --namespace ingress-basic

Remove the ingress route that directed traffic to the sample apps:

kubectl delete -f hello-world-ingress.yaml

Finally, you can delete the itself namespace. Use the kubectl delete command and specify your namespace name:

kubectl delete namespace ingress-basic

Next steps

This article included some external components to AKS. To learn more about these components, see the following project pages:

• Helm CLI
• NGINX ingress controller

You can also:

• Enable the HTTP application routing add-on
• Create an ingress controller that uses an internal, private network and IP address
• Create an ingress controller that uses your own TLS certificates
• Create an ingress controller that uses Let's Encrypt to automatically generate TLS certificates with a dynamic public IP address or with a static public IP address