Create an ingress controller to an internal virtual network in Azure Kubernetes Service (AKS)

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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. The ingress controller is configured on an internal, private virtual network and IP address. No external access is allowed. Two applications are then run in the AKS cluster, each of which is accessible over the single IP address.

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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. For more information on configuring and using Helm, see Install applications with Helm in Azure Kubernetes Service (AKS).

This article assumes that you have an existing AKS cluster. If you need an AKS cluster, see the AKS quickstart using the Azure CLI, using Azure PowerShell, or using the Azure portal.

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.

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.

Import the images used by the Helm chart into your ACR

Often when using an AKS cluster with a private network, it is a requirement to manage the provenance of the container images used within the cluster. See Best practices for container image management and security in Azure Kubernetes Service (AKS) for more information. To support this requirement, and for completeness, the examples in this article rely on importing the three container images used by the NGINX ingress controller Helm chart into your ACR.

Use az acr import to import these images into your ACR.

REGISTRY_NAME=<REGISTRY_NAME>
SOURCE_REGISTRY=k8sgcr.azk8s.cn
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

Note

In addition to importing container images into your ACR, you can also import Helm charts into your ACR. For more information, see Push and pull Helm charts to an Azure container registry.

Create an ingress controller

By default, an NGINX ingress controller is created with a dynamic public IP address assignment. A common configuration requirement is to use an internal, private network and IP address. This approach allows you to restrict access to your services to internal users, with no external access.

Create a file named internal-ingress.yaml using the following example manifest file. This example assigns 10.240.0.42 to the loadBalancerIP resource. Provide your own internal IP address for use with the ingress controller. Make sure that this IP address is not already in use within your virtual network. Also, if you are using an existing virtual network and subnet, you must configure your AKS cluster with the correct permissions to manage the virtual network and subnet. See Use kubenet networking with your own IP address ranges in Azure Kubernetes Service (AKS) or Configure Azure CNI networking in Azure Kubernetes Service (AKS) for more information.

controller:
  service:
    loadBalancerIP: 10.240.0.42
    annotations:
      service.beta.kubernetes.io/azure-load-balancer-internal: "true"

Now deploy the nginx-ingress chart with Helm. To use the manifest file created in the previous step, add the -f internal-ingress.yaml parameter. 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.

Tip

The following example creates a Kubernetes namespace for the ingress resources named ingress-basic and is intended to work within that namespace. Specify a namespace for your own environment as needed. If your AKS cluster is not Kubernetes RBAC enabled, add --set rbac.create=false to the Helm commands.

Tip

If you would like to enable client source IP preservation for requests to containers in your cluster, add --set controller.service.externalTrafficPolicy=Local to the Helm install command. The client source IP is stored in the request header under X-Forwarded-For. When using an ingress controller with client source IP preservation enabled, TLS pass-through will not work.

# 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 \
    --version 4.0.13 \
    --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=$CONTROLLER_TAG \
    --set controller.image.digest="" \
    --set controller.image.repository=$SOURCE_REGISTRY/$CONTROLLER_IMAGE \
    --set controller.admissionWebhooks.patch.nodeSelector."kubernetes\.io/os"=linux \
    --set controller.admissionWebhooks.patch.image.registry=$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 controller.service.annotations."service\.beta\.kubernetes\.io/azure-load-balancer-health-probe-request-path"=/healthz \
    --set defaultBackend.image.registry=$ACR_URL \
    --set defaultBackend.image.image=$DEFAULTBACKEND_IMAGE \
    --set defaultBackend.image.tag=$DEFAULTBACKEND_TAG \
    --set defaultBackend.image.repository=$SOURCE_REGISTRY/$DEFAULTBACKEND_IMAGE \
    --set defaultBackend.image.digest=""

When the Kubernetes load balancer service is created for the NGINX ingress controller, your internal IP address is assigned. To get the public IP address, use the kubectl get service command.

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

It takes a few minutes for the IP address to be assigned to the service, 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 internal 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.yaml file and copy in the following example YAML:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: aks-helloworld
spec:
  replicas: 1
  selector:
    matchLabels:
      app: aks-helloworld
  template:
    metadata:
      labels:
        app: aks-helloworld
    spec:
      containers:
      - name: aks-helloworld
        image: mcr.azk8s.cn/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
spec:
  type: ClusterIP
  ports:
  - port: 80
  selector:
    app: aks-helloworld

Create a ingress-demo.yaml file and copy in the following example YAML:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ingress-demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ingress-demo
  template:
    metadata:
      labels:
        app: ingress-demo
    spec:
      containers:
      - name: ingress-demo
        image: mcr.azk8s.cn/azuredocs/aks-helloworld:v1
        ports:
        - containerPort: 80
        env:
        - name: TITLE
          value: "AKS Ingress Demo"
---
apiVersion: v1
kind: Service
metadata:
  name: ingress-demo
spec:
  type: ClusterIP
  ports:
  - port: 80
  selector:
    app: ingress-demo

Run the two demo applications using kubectl apply:

kubectl apply -f aks-helloworld.yaml --namespace ingress-basic
kubectl apply -f ingress-demo.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 the address http://10.240.0.42/ is routed to the service named aks-helloworld. Traffic to the address http://10.240.0.42/hello-world-two is routed to the ingress-demo service.

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
  namespace: ingress-basic
  annotations:
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
    nginx.ingress.kubernetes.io/use-regex: "true"
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  ingressClassName: nginx
  rules:
  - http:
      paths:
      - path: /hello-world-one(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld
            port:
              number: 80
      - path: /hello-world-two(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: ingress-demo
            port:
              number: 80
      - path: /(.*)
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld
            port:
              number: 80

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

kubectl apply -f hello-world-ingress.yaml

The following example output shows the ingress resource is created.

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

ingress.networking.k8s.io/hello-world-ingress created

Test the ingress controller

To test the routes for the ingress controller, browse to the two applications with a web client. If needed, you can quickly test this internal-only functionality from a pod on the AKS cluster. Create a test pod and attach a terminal session to it:

kubectl run -it --rm aks-ingress-test --image=mcr.azk8s.cn/dotnet/runtime-deps:6.0 --namespace ingress-basic

Install curl in the pod using apt-get:

apt-get update && apt-get install -y curl

Now access the address of your Kubernetes ingress controller using curl, such as http://10.240.0.42. Provide your own internal IP address specified when you deployed the ingress controller in the first step of this article.

curl -L http://10.240.0.42

No additional path was provided with the address, so the ingress controller defaults to the / route. The first demo application is returned, as shown in the following condensed example output:

$ curl -L http://10.240.0.42

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <link rel="stylesheet" type="text/css" href="/static/default.css">
    <title>Welcome to Azure Kubernetes Service (AKS)</title>
[...]

Now add /hello-world-two path to the address, such as http://10.240.0.42/hello-world-two. The second demo application with the custom title is returned, as shown in the following condensed example output:

$ curl -L -k http://10.240.0.42/hello-world-two

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <link rel="stylesheet" type="text/css" href="/static/default.css">
    <title>AKS Ingress Demo</title>
[...]

Clean up resources

This article used Helm to install the ingress components. 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.

helm list --namespace ingress-basic

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.

helm uninstall nginx-ingress --namespace ingress-basic

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.yaml --namespace ingress-basic
kubectl delete -f ingress-demo.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:

You can also: