Edit

Tutorial: Enable application gateway ingress controller add-on for an existing AKS cluster with an existing application gateway

  • Article

You can use Azure CLI or portal to enable the application gateway ingress controller (AGIC) add-on for an existing Azure Kubernetes Services (AKS) cluster. In this tutorial, you'll learn how to use AGIC add-on to expose your Kubernetes application in an existing AKS cluster through an existing application gateway deployed in separate virtual networks. You'll start by creating an AKS cluster in one virtual network and an application gateway in a separate virtual network to simulate existing resources. You'll then enable the AGIC add-on, peer the two virtual networks together, and deploy a sample application that will be exposed through the application gateway using the AGIC add-on. If you're enabling the AGIC add-on for an existing application gateway and existing AKS cluster in the same virtual network, then you can skip the peering step below. The add-on provides a much faster way of deploying AGIC for your AKS cluster than through Helm and also offers a fully managed experience.

In this tutorial, you learn how to:

  • Create a resource group
  • Create a new AKS cluster
  • Create a new application gateway
  • Enable the AGIC add-on in the existing AKS cluster through Azure CLI
  • Enable the AGIC add-on in the existing AKS cluster through Azure portal
  • Peer the application gateway virtual network with the AKS cluster virtual network
  • Deploy a sample application using AGIC for ingress on the AKS cluster
  • Check that the application is reachable through application gateway

If you don't have an Azure subscription, create an Azure free account before you begin.

Prerequisites

Create a resource group

In Azure, you allocate related resources to a resource group. Create a resource group by using az group create. The following example creates a resource group named myResourceGroup in the East US location (region):

az group create --name myResourceGroup --location eastus

Deploy a new AKS cluster

You'll now deploy a new AKS cluster, to simulate having an existing AKS cluster that you want to enable the AGIC add-on for.

In the following example, you'll be deploying a new AKS cluster named myCluster using Azure CNI and Managed Identities in the resource group you created, myResourceGroup.

az aks create -n myCluster -g myResourceGroup --network-plugin azure --enable-managed-identity --generate-ssh-keys

To configure more parameters for the above command, see az aks create.

Note

A node resource group will be created with the name MC_resource-group-name_cluster-name_location.

Deploy a new application gateway

You'll now deploy a new application gateway, to simulate having an existing application gateway that you want to use to load balance traffic to your AKS cluster, myCluster. The name of the application gateway will be myApplicationGateway, but you'll need to first create a public IP resource, named myPublicIp, and a new virtual network called myVnet with address space 10.0.0.0/16, and a subnet with address space 10.0.0.0/24 called mySubnet, and deploy your application gateway in mySubnet using myPublicIp.

Caution

When you use an AKS cluster and application gateway in separate virtual networks, the address spaces of the two virtual networks must not overlap. The default address space that an AKS cluster deploys in is 10.224.0.0/12.

az network public-ip create -n myPublicIp -g myResourceGroup --allocation-method Static --sku Standard
az network vnet create -n myVnet -g myResourceGroup --address-prefix 10.0.0.0/16 --subnet-name mySubnet --subnet-prefix 10.0.0.0/24 
az network application-gateway create -n myApplicationGateway -g myResourceGroup --sku Standard_v2 --public-ip-address myPublicIp --vnet-name myVnet --subnet mySubnet --priority 100

Note

The application gateway ingress controller (AGIC) add-on only supports application gateway v2 SKUs (Standard and WAF), and not the application gateway v1 SKUs.

Enable the AGIC add-on in existing AKS cluster through Azure CLI

If you'd like to continue using Azure CLI, you can continue to enable the AGIC add-on in the AKS cluster you created, myCluster, and specify the AGIC add-on to use the existing application gateway you created, myApplicationGateway.

appgwId=$(az network application-gateway show -n myApplicationGateway -g myResourceGroup -o tsv --query "id") 
az aks enable-addons -n myCluster -g myResourceGroup -a ingress-appgw --appgw-id $appgwId

Important

When you use an application gateway in a different resource group than the AKS cluster resource group, the managed identity ingressapplicationgateway-{AKSNAME} that is created must have Contributor and Reader roles set in the application gateway resource group.

Peer the two virtual networks together

Since you deployed the AKS cluster in its own virtual network and the Application gateway in another virtual network, you'll need to peer the two virtual networks together in order for traffic to flow from the Application gateway to the pods in the cluster. Peering the two virtual networks requires running the Azure CLI command two separate times, to ensure that the connection is bi-directional. The first command will create a peering connection from the Application gateway virtual network to the AKS virtual network; the second command will create a peering connection in the other direction.

nodeResourceGroup=$(az aks show -n myCluster -g myResourceGroup -o tsv --query "nodeResourceGroup")
aksVnetName=$(az network vnet list -g $nodeResourceGroup -o tsv --query "[0].name")

aksVnetId=$(az network vnet show -n $aksVnetName -g $nodeResourceGroup -o tsv --query "id")
az network vnet peering create -n AppGWtoAKSVnetPeering -g myResourceGroup --vnet-name myVnet --remote-vnet $aksVnetId --allow-vnet-access

appGWVnetId=$(az network vnet show -n myVnet -g myResourceGroup -o tsv --query "id")
az network vnet peering create -n AKStoAppGWVnetPeering -g $nodeResourceGroup --vnet-name $aksVnetName --remote-vnet $appGWVnetId --allow-vnet-access

Note

In the "Deploy a new AKS cluster" step above we created AKS with Azure CNI, in case you have an existing AKS cluster using Kubenet mode you need to update the route table to help the packets destined for a POD IP reach the node which is hosting the pod. A simple way to achieve this is by associating the same route table created by AKS to the Application Gateway's subnet.

Deploy a sample application using AGIC

You'll now deploy a sample application to the AKS cluster you created that will use the AGIC add-on for Ingress and connect the application gateway to the AKS cluster. First, you'll get credentials to the AKS cluster you deployed by running the az aks get-credentials command.

az aks get-credentials -n myCluster -g myResourceGroup

Once you have the credentials to the cluster you created, run the following command to set up a sample application that uses AGIC for Ingress to the cluster. AGIC will update the application gateway you set up earlier with corresponding routing rules to the new sample application you deployed.

kubectl apply -f https://raw.githubusercontent.com/Azure/application-gateway-kubernetes-ingress/master/docs/examples/aspnetapp.yaml

Check that the application is reachable

Now that the application gateway is set up to serve traffic to the AKS cluster, let's verify that your application is reachable. You'll first get the IP address of the Ingress.

kubectl get ingress

Check that the sample application you created is up and running by either visiting the IP address of the application gateway that you got from running the above command or check with curl. It may take application gateway a minute to get the update, so if the application gateway is still in an "Updating" state on Azure portal, then let it finish before trying to reach the IP address.

Clean up resources

When no longer needed, delete all resources created in this tutorial by deleting myResourceGroup and MC_myResourceGroup_myCluster_eastus resource groups:

az group delete --name myResourceGroup 
az group delete --name MC_myResourceGroup_myCluster_eastus

Next steps

Learn more about disabling the AGIC add-on